Symposium Organizers
Radha Narayanan, Cesari and McKenna, LLP
Jingyi Chen, Univ of Arkansas
Svetlana Neretina, University of Notre Dame
Anatoliy Pinchuk, University of Colorado Colorado Springs
Symposium Support
MilliporeSigma
ED14.1: Design and Plasmonic Tuning
Session Chairs
Jingyi Chen
Svetlana Neretina
Tuesday PM, April 18, 2017
PCC North, 100 Level, Room 130
11:30 AM - *ED14.1.01
Rational Design and Plasmonic Tuning of Noble Metal Nanostructures
Yadong Yin 1
1 , University of California, Riverside, Riverside, California, United States
Show AbstractNoble metal nanostructures have been studied quite extensively in the research area of heterogeneous catalysis long before the introduction of the concept of nanoscience and nanotechnology. The significant progress achieved in the past twenty years in chemical synthesis has enabled exquisite control over not only the size but also the shape of the metal nanostructures, and therefore attracted intense interest not only in catalysis but also optoelectronics due to the well-known effect of localized surface plasmon resonance. Often the intrinsic properties associated with the simple metal nanostructures are not sufficient, and much more exciting opportunities exist in the nanostructure ensembles. In this presentation, I will introduce our recent progress in the stabilization, assembly, and functionalization of the metal nanostructures. The first part will be focused on reviewing our efforts in stabilizing metal nanostructures by alloying, physical confinement, and surface modification, along with their excellent performance in sensing and catalysis. In the second part, I will report the assembly and disassembly of plasmonic metal nanostructures and the associated opportunities in the development of novel optical devices such as stress-responsive colorimetric sensors that can memorize the stress that the system has experienced. Finally, I will introduce the dynamic optical control enabled by the orientational dependence of surface plasmon resonance of anisotropic nanostructures.
12:00 PM - *ED14.1.02
Surface Chemistry of Gold Nanorods
Catherine Murphy 1
1 , University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Show AbstractGold nanorods have potential applications as chemical sensing, biological imaging, and photothermal therapeutics, all of which arise from nanorods’ plasmonic properties. Our laboratory has developed the syntheses of these materials, in controlled size and shape, over the last decade. Surface modification of these nanomaterials is a key step to enable applications. In this talk I will describe how we coat nanorods with both hard shells and soft shells, including layer-by-layer polyelectrolyte deposition in aqueous solution, in a way that allows for “capture coating” of small molecules at defined distances from the surface; how plasmons affect molecular photophysics as a function of distance from the nanoparticle surface; and what kinds of chemistry are possible at plasmonic surfaces.
12:30 PM - ED14.1.03
Synthesis and Magnetic Manipulation of Anisotropic Magnetic/Plasmonic Nanocomposites
Xiaojing Wang 1 2 , Yadong Yin 1 2
1 Material Science and Engineering Program, University of California Riverside, Riverside, California, United States, 2 Department of Chemistry, University of California Riverside, Riverside, California, United States
Show AbstractWe report in this presentation the synthesis of anisotropically shaped nanocomposites that combines magnetic and plasmonic properties, and demonstrate dynamic tuning of the plasmonic properties using external magnetic fields. The response of magnetic anisotropic nanostructures to an external magnetic field is utilized to control their orientation and subsequently the optical property of the attached plasmonic components. Akaganéite nanorods are used as the starting materials, coated with a layer of noble metal, and then reduced to fabricate the core-shell magnetic/plasmonic composite nanorods. By careful tuning of the synthesis parameters, nanocomposites with different size and optical property could be readily obtained. We will discuss in detail the systematic characterization of the composition and structure of the nanocomposites and the magnetic manipulation of their optical properties. Benefitting from the unique combination of anisotropic magnetic structure and orientation-dependent plasmonic properties, the as-synthesized novel nanocomposites could find potential applications in areas such as anti-counterfeiting and data storage.
12:45 PM - ED14.1.04
Magnetite Functionalization of Silica-Overcoated Gold Nanorods via Controlled Heteroaggregation
Brian Chapman 1 , Wei-Chen Wu 1 , Qiaochu Li 2 , Niels Holten-Andersen 2 , Joseph Tracy 1
1 Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina, United States, 2 Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show Abstract
By assembling different kinds of nanoparticles (NPs), novel optical, magnetic, electronic, or catalytic properties can be integrated in multifunctional NPs that are not available in NPs of a single type. The ability to build multifunctionality within individual NPs is potentially useful in a wide range of applications, including optoelectronics, catalysis, multimodal imaging, drug delivery, sensing, and catalysis. Methods for assembling composite nanoparticles include seeded growth of one kind of NP onto another and linking two or more types of NPs together using chemical (e.g., small molecule linkers, DNA) or physical (e.g., electrostatic attraction, entrapment) means. Each of these methods has advantages and disadvantages, and a need remains to design simple, effective, and broadly applicable methods for preparing multifunctional NPs.
Here we report a method for depositing magnetite (Fe3O4) NPs onto the surface of silica-overcoated gold nanorods (SiO2-GNRs) via nonsolvent-induced heteroaggregation. While the principle of heteroaggregation is well established, it surprisingly underutilized for assembly of multifunctional NPs. Under certain conditions, mixing magnetite (Fe3O4) NPs stabilized by oleylamine and dispersed in a nonpolar solvent with SiO2-overcoated GNRs (SiO2-GNRs) dispersed in a polar solvent results in controlled deposition of Fe3O4 NPs onto the surface of SiO2-GNRs. The nonsolvent drives the Fe3O4 NPs onto the surface of the SiO2-GNRs through heteroaggregation, resulting in a Fe3O4-SiO2-GNRs with a core/satelite morphology with a high yield in under 20 minutes. The density of the Fe3O4 NP coating can be controlled by varying the ratio of Fe3O4 NPs to SiO2-GNRs. The Fe3O4-SiO2-GNR products maintain the longitudinal surface plasmon resonance of SiO2-GNRs and exhibit a strong magnetic response, which allows for magnetic separation within 60 minutes using permanent magnets. As prepared, Fe3O4-SiO2-GNRs disperse in nonpolar solvents (e.g., hexanes, THF, toluene) because of the oleylamine ligands on the Fe3O4 NPs that are exposed to the solvent. Fe3O4-SiO2-GNRs can be rendered dispersible in polar solvents (e.g., water, ethanol, methanol) by functionalizing the Fe3O4 NP surface coating on the SiO2-GNRs with poly(ethylene glycol)-catechol. This heteroaggregation approach is simple, effective, and potentially broadly applicable for driving assembly of combinations of NPs with hydrophilic and hydrophobic surface coatings.
ED14.2: Tailoring Plasmonic Activity
Session Chairs
Jingyi Chen
Svetlana Neretina
Tuesday PM, April 18, 2017
PCC North, 100 Level, Room 130
2:30 PM - *ED14.2.01
Triangular Silver Nanoprism Based Nanostructures—Synthesis, Optical Properties and Applications
Can Xue 1
1 , Nanyang Technological University, Singapore Singapore
Show AbstractTriangular silver nanoprisms have size-dependent plasmon bands that are tunable in the visible and near-IR region, and highly sensitive to the dielectric environment. However, the pure silver structures are vulnerable to oxidative etching, which restricts their applications. Herein we present a general surfactant-free strategy to functionalize silver nanoprisms with gold through simultaneous addition of HAuCl4 and hydroxylamine with precise control on the infusion rate. By tuning the reactant concentrations and reaction time, we have obtained different bimetallic triangular nanostructures including edge-gold coated Ag nanoprism, Ag@Au core-shell nanoprism, and AgAu nanoframe. These gold-modified Ag nanostructures exhibit remarkably improved stability against chemical etching, and thereby show excellent performance for refractive index sensing and plasmon-enhanced polaron generation in organic photovoltaics. Further, similar functionalization strategies were applied for Pd coating, and we have obtained triangular AgPd alloy nanoprisms and nanoframes, which showed enhanced electrocatalytic activities for oxygen reduction and methanol oxidation.
3:00 PM - *ED14.2.02
Combining Bottom Up with Top Down for Tailoring Plasmonic Activity
Jennifer Shumaker-Parry 1 , Cady Lancaster 1 , Wallis Scholl 1 , Matthew Ticknor 2
1 Department of Chemistry, University of Utah, Salt Lake City, Utah, United States, 2 Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah, United States
Show AbstractBy combing bottom up wet chemical synthesis with top down fabrication, plasmonic nanostructures with tailored optical properties are created. Arrayed nanostructures fabricated using nanosphere lithography serve as a foundation for seeding the growth of additional structural features that lead to new localized surface plasmon resonance properties as well as optical near field effects. One example is the decoration of plasmonic nanotriangles with silver features to create urchin-like structures. The growth of the triangle-based nanourchins involves well-controlled synthetic conditions including solution pH, temperature and reagent addition. The nanourchins produce enhanced signals in both surface enhanced Raman scattering spectroscopy and surface enhanced infrared absorption spectroscopy compared to the original nanotriangles due to the optical near fields at the high asperity surface of the decorated nanostructures.
3:30 PM - ED14.2.03
Shape-Engineering Complex Nobel Metal Nanostructures through the Integration of Seed-Mediated Colloidal Syntheses with Substrate-Based Fabrication Techniques
Robert Hughes 1 , Svetlana Neretina 1 , Eredzhep Menumerov 1
1 College of Engineering, University of Notre Dame, Notre Dame, Indiana, United States
Show AbstractThe chemical controls realizable through seed-mediated colloidal syntheses have given rise to an entire class of shape-engineered noble metal nanostructures where exquisite control is exerted over their size, faceting, and elemental make-up. While the application of such structures often relies on the nanostructure mobility facilitated by suspensions, many other functionalities require nanostructure immobilization on the surface of a planar substrate. While many methods exist for the dispersal of colloids onto substrates, few are capable of achieving nanostructure ensembles where nanostructure placement allows for true long range order as well as control over the crystallographic alignment of the nanostructures relative to each other and the underlying substrate. Here, we describe a procedure for obtaining organized surfaces of noble metal nanostructures through the integration of substrate-based techniques with well-established colloidal syntheses. It is demonstrated that physical vapor deposition, lithography, and vapor phase directed assembly techniques, when used in combination with galvanic replacement, preferential etching, and/or heterogeneous deposition facilitated by redox reactions, can give rise to an entire family of shape-engineered nanostructures formed at predefined locations on the substrate surface. While many of these structures bare a resemblance to well-known colloids shaped as nanocubes, truncated octahedra, nanoprisms, nanoshells, nanocages, nanoframes, core-shell structures, and nanorattles, in no case are they identical since the substrate inflicts asymmetries onto the growth mode. Moreover, we are able to exploit the epitaxial relationship formed between the nanostructure and the underlying crystalline substrate to ensure that adjacent nanostructures are identically aligned on the substrate surface. The unique nanostructure architectures formed along with the intrinsic advantages available through the integration of substrate- and solution-based techniques have the potential to underpin both existing and new applications reliant on substrate-immobilized nanostructures.
1 S. Neretina, R. A. Hughes, K. D. Gilroy, M. Hajfathalian, Noble Metal Nanostructure Synthesis at the Liquid–Substrate Interface: New Structures, New Insights, and New Possibilities. Acc. Chem. Res. 2016, DOI: 10.1021/acs.accounts.6b00393.
3:45 PM - ED14.2.04
Microfluidic Colloidal Nanorods Array Alignment for Circulating Biomarker Detection
Amogha Tadimety 1 , Kasia Kready 1 , Timothy Palinski 1 , Hamid Chorsi 1 , John Zhang 1 2
1 Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, United States, 2 Norris Cotton Cancer Center, Dartmouth College, Lebanon, New Hampshire, United States
Show AbstractThe concept of liquid biopsy and the promise of less invasive diagnostics is key to the emerging era of precision medicine, where early detection of disease can be accomplished through real time detection of clinically relevant biomarkers in low-volume human fluid samples such as blood. Plasmonic sensors, when combined with microfluidic chips, hold great promise because they offer a complete microsystem to perform both sample enrichment and detection. This combination will allow sensitive, multiplexed and label-free detection of circulating tumor biomarkers at low concentration. Here we demonstrate an unconventional method to fabricate ordered nanorod arrays, where a nanowrinkle template was created first as an assembly site for nanorods deposition, screening of biomarkers, and plasmonic detection.
Tunable macroscale templates of nanowrinkles were formed using a simple stretch-release and plasma treatment process. Gold nanorods were then aligned over these nanowrinkle templates using custom microfluidic channels, enabling the near-field interactions of samples with the substrate and allowing the formation of micro-scale sensing spots. In order to produce consistent wrinkled templates, a custom polydimethylsiloxane (PDMS) stretcher was 3D printed to allow for slow release of the stretched and plasma-treated polymer. The templates were analyzed using atomic force microscopy (AFM) demonstrating wrinkles ranging from 30 to 100nm in amplitude, and 50nm to 1 micron in periodicity. Gold nanorods were then deposited into the templates using microfluidic channels with a grid of sensing spots for multiplexed sensing. Preliminary alignment results, taken using scanning electron microscopy (SEM), suggest that 80% of nanorods are aligned within 1 degree of rotation from the nanowrinkle axis, with 95% of the nanorods aligned within 5 degrees. Surface conjugation chemistry of the nanorods was designed to enhance electrostatic and wetting interactions for microfluidic-aided nanorod alignment within the wrinkles.
The optical extinction spectra of the nanoarrays were characterized using both computer modeling and a benchtop optical detection system. For wavelengths from 400nm to 900nm, nanoarray geometries were evaluated in terms of the sensitivity to refractive index variations and extinction spectrum, and the experimental results were compared to simulations. The benchtop optical detection system produced an extinction spectrum similar to the simulations, with an absorption peak at around 600nm.
The demonstrated method of topologically wrinkled substrate fabrication combined with microfluidic chips can provide ordered nanoarrays with the dual function of biomarker enrichment and on-chip detection. This compact system requires a smaller concentration of noble metal particles with greater sample control.
4:15 PM - ED14.2.05
Electronic Behavior of Fluorophore Modified Superatom Gold Clusters
Mary Sajini Devadas 1 , Angela Meola 1 , Viraj Thanthirige 2 , Keith Reber 1 , Erik Hobbs 3
1 Department of Chemistry, Towson University, Towson, Maryland, United States, 2 Department of Chemistry, Western Michigan University, Kalamazoo, Michigan, United States, 3 Department of Physics, Towson University, Towson, Maryland, United States
Show AbstractOver the past two decades superatom clusters of gold have attracted much attention in the fields of biomedicine, plasmonic and energy related research. The key distinguishing feature in superatom gold is its exceptional chemical reactivity to CO oxidation, hydrogenation, selective oxidation afforded by electron transfer. Their use as biological imaging agents is being probed due to their near-IR luminescence. These electronic properties are exhibited due to their differences in electronic structure when they attain a superatom configuration, which alludes to size and site dependent activation energies and reaction rates, proved by joint experimental and theoretical studies. Superatom Au25L18, and Au144L60 clusters were synthesized using established protocols with L = hexanethiol as a stabilizing ligand. The electronic behavior was established through linear and non-linear optical methods and electrochemistry. These clusters where then modified with a fluorophore-a modified coumarin via exchange reaction and direct synthesis. The details of the synthesis, characterization and ultra-fast measurements will be presented.
4:30 PM - *ED14.2.06
Stress Induced New Plasmonic Nanostructures
Hongyou Fan 1 2
1 , Sandia National Laboratories, Albuquerque, New Mexico, United States, 2 , University of New Mexico, Albuquerque, New Mexico, United States
Show AbstractOne of the outstanding challenges in the emerging fields of nanophotonics is the ability to achieve precise control in macroscopic nanoparticle (NP) superlattices of structural characteristics such as interparticle distance so as to enhance efficiency of charge/energy transfer. To this aim, both top-down processes such as e-beam and ion-beam lithography and bottom-up methods such as self-assembly of colloidal NPs have been vigorously pursued. While these methods have provided certain success, they have essential fundamental limitations. The top-down processes are limited by their spatial resolutions of ~10nm by the e-beam/ion-beam size and by their inability to fabricate complicated and tunable 3D nanostructures. Bottom-up methods have been limited to 2nm interparticle distances by the NP surface ligands. Here we show a new stress-induced fabrication method to produce new classes of 1-3D plasmonic nanostructures with precisely and systematically controlled structural characteristics for strong and tunable collective optical properties. The method allows reversible manipulation of structural characteristics such as interparticle distance under stress and offers unique robustness for in situ interrogation of both chemical and physical coupling in NP assembly, which has not been possible for both top-down and bottom up methods.
Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
5:00 PM - *ED14.2.07
General Strategy to Control High Index Facet of Plasomonic Nanoparticle
Ki Tae Nam 1 , Hye-Eun Lee 1 , Hyo-Yong Ahn 1
1 Materials Science and Engineering, Seoul National University, Seoul Korea (the Republic of)
Show AbstractNanoparticles enclosed by high-index facets have attracted attention because of their unexpected catalytic and optical properties. The fascinating catalytic properties of high-index facets result from the high density of atomic steps that can serve as active sites for chemical reactions. Geometrically unique shape created by high index surfaces can amplify electromagnetic effect offering compelling optical applications such as optical antenna, imaging, and chemical sensor.
Here we developed a new way to produce high-index nanoparticles by using organothiol as a shape-controlling additive. The role of organothiol has two fold in directing the crystal growth. Thiol group in the molecule acts as anchor that tightly binds the molecule onto the metal surface. Various functional groups in organothiol make characteristic attachment onto the surface determining the direction of growth. From a library of chemicals containing a benzene group and a thiol group, we identified a new benzenethiol ligand that directs shape evolution during seed-mediated growth and stabilizes the high facet. The benzenethiol co-existing with precursors in growth solution is gradually attached to seed and significantly alters the growth pathway of the seed. Depending on the bonding energy between gold and thiol, the position of functional group, and the presence of the benzene ring, the resulting crystal showed different morphologies.
As an example, a new class of high-index nanoparticles, the concave rhombic dodecahedron (RD), was synthesized utilizing 4-aminothiophenol (4-ATP). The concave RD can be delineated by excavating out two triangular pyramids from each (110) surface of the RD shape. Through careful analysis of the growth mechanism, we found that the concave features originate from the dominant growth of the edge, as the 4-ATP gradually covers the flat surface of the RD. Surprisingly, we found nine different combinations of terraces and steps in the individual concave RD. Various terrace units from (110) to (443) and different type of (331) surface were identified according to local degree of curvature in the nanoparticle. These numerous facets in the concave RD allow the nanoparticle to have a high density of atoms with low coordination number, making this nanoparticle ideal as a catalyst. With various stepped surfaces, the concave RD exhibits improved activity and selectivity for electrochemical reduction of CO2. Moreover, the concave RD displays superior stability for long-term electrochemical performance and storage.
This new methodology and novel morphology will open up new possibilities for not only synthesizing intriguing morphology, but also fabricating various catalysts.
5:30 PM - ED14.2.08
Electrohydrodynamic Flow as a Driving Force for the Directed Chemical Assembly of Plasmonic Metasurfaces
Will Thrift 1 , Cuong Nguyen 1 , Mahsa Darvishzadeh-Varcheie 1 , Filippo Capolino 1 , Regina Ragan 1
1 , University of California, Irvine, Irvine, California, United States
Show AbstractAdvances in understanding chemical and physical driving forces in self-assembly allow the fabrication of unique nanoarchitectures with subwavelength building blocks as the basis for plasmonic and metamaterial devices. Directed assembly of colloidal nanospheres has been shown as a promising method for producing large area plasmonic metasurfaces. Still, obtaining the uniformity and packing fraction necessary for many sophisticated metasufaces remains elusive. In this work, electrohydrodynamic (EHD) flow and chemical crosslinking are combined to form dense Au nanosphere clusters (oligomers) in the 2-dimensional plane of a working electrode. EHD provides a long range driving force to bring nanospheres together and crosslinking yields small, uniform gap spacings which yield strong light-matter interactions. This work represents a novel use of EHD flow for directed assembly to improve assembly kinetics. Using selective chemistry, nanospheres are crosslinked onto block copolymer templates and e-beam fabricated templates. We investigate nanoantenna optical response via full wave simulations, dark field scattering spectroscopy, and surface enhanced Raman scattering (SERS). Fully self-assembled sensors are fabricated with over large areas, with a relative standard deviation of just 10% measured over over a 1 mm2 area with an average SERS EF of 1.4×109. Plasmonic metasurfaces for enhancing the magnetic near field are fabricated using templates. Understanding long range (EHD flow) and short range (chemical crosslinking) driving forces provides the control for assembling colloidal nanoparticles in architectures for large area plasmonic metasurfaces such as perfect absorbers and wavefront shaping.
5:45 PM - ED14.2.09
In-Line Linear and Non-Linear Optical Spectroscopy of Plasmon Resonant Nanoshells Grown in a Continuous Flow Microreactor
Shuji Ohsaki 2 , Rebecca Dinkel 1 3 , Thomas Meincke 1 3 , Bjoern Braunschweig 1 4 5 , Satoshi Watanabe 2 , Robin Klupp Taylor 1 4 5
2 Department of Chemical Engineering, Kyoto University, Kyoto Japan, 1 Institute of Particle Technology, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen Germany, 3 Graduate School "Advanced Materials and Processes", Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen Germany, 4 Interdisciplinary Center for Functional Particle Systems, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen Germany, 5 Cluster of Excellence "Engineering of Advanced Materials", Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen Germany
Show AbstractCurrently there is an increasing trend to produce plasmon resonant nanoparticles using continuous flow liquid phase synthesis. On the one hand, this approach allows the scale up of successful, small-scale syntheses through parallelization. On the other hand, more precise control over mixing processes, which may strongly influence nucleation and growth events and affect the distribution of nanoparticle morphologies and properties, is achieved. Unlike batch processing, the conditions of a continuous flow synthetic process can be adjusted in operando in order to optimize the properties of the produced particles. In the case of plasmon resonant particles, it is feasible in this way to precisely obtain plasmon resonances at desired wavelengths. In order for a high level of process control over properties to be achieved, a better understanding of the particle growth kinetics is required. The continuous flow process offers here an opportunity because particles at different reaction residence times are spatially separated and thus can be analysed by optical spectroscopy.
In this contribution we consider the case of gold nanoshells growing via a seeded growth route. Seed particles comprising gold nanocrystals distributed over silica cores with different diameters were combined with a gold-containing precursor and then mixed in a KM-type static micromixer with a reducing agent. Following the mixer, a glass capillary provided optical access to the growing gold shells. The capillary was translated through the optical path so as to scan through a range of reaction residence times and thus enable various stages of stage growth to be optically analysed. We applied two types of spectroscopy in this in-line system. The first was linear UV/VIS/NIR extinction spectroscopy. This revealed the well-known shifts of the plasmon resonance corresponding to growth and coalescence of gold islands on the surface of the silica core particles. The final spectrum corresponded well with that predicted by multishell Lorenz-Mie theory and scanning electron micrographs confirmed good quality nanoshells were produced. The second optical method used was second harmonic generation (SHG) spectroscopy. This highly surface-sensitive nonlinear method revealed complementary information about the growing shells, in particular providing an insight into the early stages of seed coalescence, an aspect not accessible by linear spectroscopy due to the weak, broad plasmon features associated with the large number of electrodynamically coupled metal islands. Finally, by comparing the trends in SHG and UV/VIS/NIR spectra for different core particles sizes we could estimate aspects of the nanoshell growth kinetics.
ED14.3: Poster Session I: Synthesis and Applications of Plasmonic Nanomaterials
Session Chairs
Jingyi Chen
Radha Narayanan
Svetlana Neretina
Anatoliy Pinchuk
Wednesday AM, April 19, 2017
Sheraton, Third Level, Phoenix Ballroom
9:00 PM - ED14.3.01
Metal Nanocrystals with Plasmon Tunable in the Infrared Region and Their Application for Surface-Enhanced Infrared Absorption
Nannan Li 1 , Xiaolu Zhuo 1 , Jianfang Wang 1
1 , The Chinese University of Hong Kong, Hong Kong China
Show AbstractPlasmonics has been extensively investigated as one of the hottest topics in nanomaterials and nanophotonics. During the last two decades, a variety of methods for the preparation of metal nanocrystals resonant at visible frequencies have been developed. But their counterparts in near-infrared (NIR) and mid-infrared (MIR) regions are far less advanced, because of the difficulties in the colloidal synthesis of metal nanocrystals with high anisotropy and high uniformity. However, they are essential for developing plasmonic light manipulation in the NIR and MIR regions, for medical detection and chemical sensing. In particular, surface-enhanced infrared absorption (SEIRA), a complement of surface-enhanced Raman scattering (SERS), has received growing attention recently. For SEIRA, molecular vibrations resonant with localized plasmon can be largely enhanced by ~104 times on the basis of the strong local field enhancement of plasmonic nanostructures, so that molecules can be detected by SEIRA down to the amol level.
We have developed a method for the synthesis of high-quality Ag nanorods of aspect ratios variable from 5 to 35 through Au nanobipyramid-directed Ag overgrowth. The Ag nanorods have narrow size distribusions in both diameter and length. The high uniformity of these high-aspect-ratio Ag nanorods allows us to observe narrow-band localized surface plasmon resonance in the NIR and MIR regions. Their plasmon wavelengths can be tuned from ~1 to ~10 μm, covering the “fingerprints” of most molecular vibrations. We carefully investigated the SEIRA performance of our Ag nanorods by tuning the plasmon wavelength close to or away from the C-H stretches of cetyltrimethylammonium bromide (CTAB) molecules adsorbed on the surface of the nanorods. When the plasmon wavelength of the Ag nanorods is resonant with the molecular vibrations, enhanced IR signals are obtained from a miniscule amount of CTAB probe molecules. Furthermore, we successfully prepared Au nanotubes that are highly uniform in the outer diameter, wall thickness and length through galvanic replacement reaction from the Ag nanorods. Their high chemical stability, high biocompatibility and highly tunable plasmon wavelengths make them an attractive candidate for plasmon-based optical and biotechnological applications in the NIR and MIR regions.
To the best of our knowledge, our study is not only the first on colloidally synthesized metal nanostructures with tunable plasmons in the NIR and MIR regions, but also the first successful demonstration on their application for SEIRA. Our results point out a promising route to the use of chemically synthesized, colloidal metal nanostructures for SEIRA as well as for the exploration of such nanostructures in ultra-sensitive bio- and chemical sensing in the IR regions.
9:00 PM - ED14.3.02
Facile Synthesis of Oleylamine-Capped Silver Nanowires and their Application in Transparent Conductive Electrodes
Yiqun Zheng 1
1 , Shandong University, Jinan China
Show AbstractWe report a facile method for the synthesis of oleylamine-capped silver (Ag) nanowires in high purity. For the first time, Ag nanowires could be produced in high purity via a simple one-pot approach in a hydrophobic phase. The success of this synthesis relies on the use of Cu2+ to mediate the reduction of silver bromide (AgBr) by oleylamine at an elevated temperature, which promoted the high-yield formation of Ag products with a wire-like shape. These Ag nanowires were washed and deposited on PET films to form a transparent conductive electrode (TCE), which showed a sheet resistance of 34.0 Ω sq-1 and an optical transmittance of 70-80% at visible wavelengths. In addition to TCEs, these nanowires could also find important applications in the fields of conductive ink, and wearable electronics, among others.
9:00 PM - ED14.3.03
Understanding and Controlling the Morphology of Silica Shells on Gold Nanorods
Laurel Rowe 1 , Brian Chapman 1 , Joseph Tracy 1
1 Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina, United States
Show AbstractSubtle variations in the conditions for addition of a tetraethyl orthosilicate (TEOS) / methanol (MeOH) solution to gold nanorods (GNRs) stabilized by cetyltrimethylammonium bromide (CTAB) allow for morphological control of the silica (SiO2) shells deposited onto the GNRs. Varying the concentration of TEOS in the TEOS/alcohol mixture yields SiO2-coated GNRs (SiO2-GNRs) with morphologies that can be adjusted from fully encapsulated to lobed structures. Changes in the optical absorbance of SiO2-GNRs after purification with MeOH suggest that CTAB can be dissolved through the porous SiO2 shells. The size of the lobes can be controlled, but there is a minimum lobe size, below which full encapsulation is favored. The following mechanism of lobe formation is proposed: Initially, a SiO2 shell fully encapsulates the CTAB-stabilized GNR core. Under certain reaction conditions, the SiO2 shell can reshape into lobes, which are more thermodynamically stable because they minimize the surface energy. In addition to use of a minimum amount of TEOS critical for achieving lobes, a MeOH concentration near 9 v% is also necessary for lobing. Formation of lobed structures may be attributed to the protic nature of MeOH, which allows it to participate in reverse sol-gel reactions and thereby facilitates repeated depolymerization and polymerization reactions, and drives deposition of SiO2 into thermodynamically favored lobed structures. Patchy nanoparticles, such as lobed SiO2-GNRs are of interest for applications in self-assembly and spatially controlled functionalization. The mechanistic insights gained through this study may be applicable to related core materials and the deposition of other kinds of oxides.
9:00 PM - ED14.3.04
Laser-Induced Periodic Metal Structures for Excitation of Surface Plasmons and for Sensing Applications
Igor Dmitruk 1 2 , Nataliya Berezovska 1 , Andriy Dmytruk 2 , Ivan Blonskyi 2 , Svyatoslav Vovdenko 1 , Oleg Yeshchenko 1
1 , National Taras Shevchenko University of Kyiv, Kyiv Ukraine, 2 Department of Photonic Processes, Institute of Physics, Kyiv Ukraine
Show AbstractDirect surface modification of materials using powerful laser pulses attracts much attention because of its simplicity, low cost and applicability to different materials. Micro- and nanostructures on metal surfaces (gold, silver, and copper) have been obtained by the irradiation of the initial surface with Ti:sapphire femtosecond laser. The laser pulse with the wavelength of 800 nm, pulse duration of 130 fs, pulse energy around 0.8 mJ, repetition rate of 1 kHz focused on the surface with a long focal length lens. The variation of the laser power density was done changing the distance of the sample from lens focus point. The most probable mechanism of formation of quasi-periodic surface structures is associated with an interference of incident electromagnetic wave and surface plasmon polaritons (SPP) excited by the incident wave on the rough metal surface.
The morphology of metal surface has been studied with atomic force microscopy (AFM), scanning electron microscopy (SEM), and the light scattering indicatrices analysis. Laser-induced surface periodic structures could be considered as quasi-periodic diffraction gratings with the period smaller than the wavelength of the laser radiation. Changing irradiation regime we try to obtain laser-induced structures with parameters suitable for grating excitation method of surface plasmons. The evidence of the excitation of SPP on the laser-induced metal nanostructures has been demonstrated by the measurements of the specular reflectance spectra. Possibility of the field enhancement due to the resonant excitation of SPP has been realised by the effect of SERS of Rhodamine 6G and Methylene Blue dyes on obtained laser-induced nanostructures.
Raman spectra of Rh6G adsorbed on laser-induced Cu, Ag, Au structures and the non-treated surfaces have been studied under different excitation wavelengths, and also for different regimes of laser treatment of the substrate. In the case of silver Raman spectra obtained under the excitation wavelength of 476,5 nm demonstrate greater Raman signal enhancement. From the analysis of the ratio of intensity of Raman bands on the structured and initial surface, the gain coefficient achieve a value up to 20. In this case, such behaviour proves that the dominant mechanism of SERS of Rh6G on formed laser-induced Ag nanostructure is electromagnetic mechanism that involves resonant excitation of surface plasmons.
Formed structures are promising for many important applications such as plasmonic emitters, biosensors, surface enhanced Raman spectroscopy (SERS), etc.
9:00 PM - ED14.3.05
Colloidal Gold Nanoring-Based Structures for Magnetic Plasmon Resonance
Tsz Him Chow 1 , Ximin Cui 1 , Qifeng Ruan 1 , Jianfang Wang 1
1 , The Chinese University of Hong Kong, Hong Kong Hong Kong
Show AbstractGold nanocrystals have attracted tremendous attention owing to their extraordinary optical properties and potential applications in many areas. It is of great importance to fabricate shape-controlled gold nanocrystals with monodispersity for manifesting clearly their plasmon resonances to confine and manipulate light at nanoscale. Au nanorings are one type of intriguing nanocrystals being studied owing to their particular geometry, highly tunable localized surface plasmon resonance (LSPR) from the visible to near-infrared region, and large and uniform electromagnetic field enhancement inside the inner circular region. Herein, we present the synthesis and preparation of colloidal split Au nanorings and Au nanoring-based heterodimers to realize magnetic plasmon resonance as well as Fano resonance.
Nature lacks materials that can support strong magnetic resonance in the optical region, yet magnetic resonance is generally required for producing metamaterials, which have many breakthrough applications, such as negative refraction, optical cloaking and superlensing. Magnetic resonance was first realized in plasmonic metal nanostructures fabricated by physical methods, such as split-ring resonators. It has remained challenging to prepare high-quality plasmonic nanocrystals with strong magnetic resonances through simple chemical methods. We have synthesized colloidal Au nanorings with controllable sizes. By use of focused ion beam, we have been able to cut a portion off a nanoring to produce split nanorings. Experiments and systematic numerical simulations have revealed the occurrence and the evolution trends of magnetic plasmon resonance along with the size of the portion that is cut off.
Because of the unique geometry of Au nanorings, their inner region can hold other optical components, which can vice versa perturb the plasmon resonance on the nanoring. Several studies have been reported on the appearance of strong Fano resonances in lithographically fabricated ring/disk nanostructures. In comparison with physically fabricated metal nanostructures, chemically grown metal nanocrystals possess better plasmonic properties owing to their better crystallinity. We have successfully prepared heterodimers out of colloidal Au nanorings, nanospheres and nanorods, where one nanosphere or one nanorod is situated inside a nanoring. Single-particle dark-field scattering imaging and spectroscopy, in conjunction with numerical simulations, indicate that such heterodimers exhibit strong Fano resonance. The observed Fano resonance is found to strongly depend on the exact position of the Au nanosphere/nanorod inside the nanoring. We believe that our study points out a way to the chemical synthesis of plasmonic metamolecules with strong magnetic plasmon resonances as well as Fano resonance. Our method will facilitate the exploration of such metamolecules in the construction of advanced metamaterials and in the development of high-performance Fano-based sensing devices.
9:00 PM - ED14.3.06
Chemical Synthesis of Gold Nano-Bars for Optical Circuitry Applications
Erik Hobbs 2 , Mary Sajini Devadas 1
2 Department of Physics, Towson University, Towson, Maryland, United States, 1 Department of Chemistry, Towson University, Towson, Maryland, United States
Show AbstractThe aim of this research is to establish a reliable chemical synthesis route to produce plasmonic gold nanobars. Gold nanobars have been synthesized through chemical reduction in the presence of surfactants: polyvinylpyrrolidone (PVP) and sodium dodecylsulfide (SDS), and in the presence of a metal cation. Synthesis was executed by varying the concentration of PVP and SDS, and introducing metal cations such as copper, platinum, palladium, or silver to the reaction. Resulting plasmonic gold nanobars were viewed under dark field microscopy and scanning electron microscopy (SEM) to visualize the nanoparticle product mixture. SEM was also implemented to obtain length and width measurements of the gold nanbars. Atomic force microscopy was employed to obtain height and tip profiles of the gold nanobars. X-ray diffraction determined the degree of crystallinity of the synthesized gold nanobars. The results of these experiments will be presented.
9:00 PM - ED14.3.07
Porous Ag-Au Bimetallic Alloy Nanoparticles for Surface Enhanced Raman Scattering
Nisha Kero 1 , R.K. Soni 1
1 Department of Physics, Indian Institute of Technology Delhi, New Delhi India
Show AbstractSurface enhanced Raman scattering (SERS) has emerged as a powerful spectroscopic technique for trace detection of molecules. This is a consequence of large electromagnetic field enhancement due to the excitation of localized surface plasmon (LSP) modes in metal nanoparticles (NPs).The availability and accessibility of high density of ‘hot spots’ is critical for the amplification of Raman signal of analyte molecules. High local electric field (EF) intensity at sharp metal tips and small nanogaps is accessible to only a small fraction of analyte molecules. Recently, porous metal nanoparticles with high density of inherent ‘hot spots’ have gained attention. Here, we report a single step synthesis of porous Ag-Au alloy nanoparticles exploiting the competition between alloying from the simultaneous reduction of AgNO3 and HAuCl4 and de-alloying due to galvanic replacement reaction. Effect of the concentrations of AgNO3, HAuCl4 and PVP on the porosity and morphology of particles were investigated. PVP capping was removed from the surface of the NPs which is otherwise detrimental to the performance of SERS sensors. UV-Vis absorption measurements showed a broad plasmonic peak centered at 540 nm. The scanning electron micrographs revealed cuboidal nanoparticles with dimensions ~ 300-400 nm. FESEM and HRTEM micrographs characterized the porosity and crystallanity of the synthesized particles. The SERS activity of the porous alloy nanoparticles was investigated using RhB dye molecules. We numerically calculated the EF enhancement in the synthesized particles using Finite Element Method. Numerical simulations and experimental results suggest that these porous NPs show high EF enhancement even in off-resonance condition. This strategy forms potential substrates for chemical sensing and efficient contrast agents for molecular imaging.
9:00 PM - ED14.3.08
Indium Nanoparticles for Ultraviolet Surface-Enhanced Raman Scattering
Rupali Das 1 , R.K. Soni 1
1 Physics, Indian Institute of Technology Delhi, New Delhi, Delhi, India
Show AbstractIn recent years surface-enhanced Raman scattering (SERS)has emerged as an efficient molecular spectroscopy technique for ultra-sensitive, non-destructive detection and analysis of low analyte concentration. Though generic substrates based on gold and silver nanostructures have been extensively explored to obtain high local electric field enhancement,the field enhancement is limited to the visible-NIR region of the electromagnetic spectrum. The template synthesis of controlled nanoscale size other metallic nanostructures have been recently explored due to their ease of synthesis and extended to various probable applications in optoelectronic, catalysis and magnetism. Indium (In0) nanoparticles exhibit active surface Plasmon resonance (SPR)in ultraviolet (UV) and deep-ultaviolet (DUV) region with optimal absorption losses.This extended accessibility combined with low cost makes indium a promising material for UV plasmonic, chemical sensing, surface enhanced Raman spectroscopy (SERS)and more recently in DUV-SERS. In this work, we report one-pot citrate capped synthesis of spherical In0 nanoparticles by borohydride induced reduction method. Effective size controlled In0 nanoparticles were obtained by rapid addition of NaBH4 with local surface plasmon resonance near 280nm. The as-synthesized In0 nanoparticles were then coated with thin silica shells by a modified Stober method. A thin coating of silica shell protects the nanoparticles from agglomeration, direct contact with the probed molecules as well as prevents oxidation of the nanoparticles. Morphological evolution of In0 nanoparticles and SiO2 coating were characterised by transmission electron microscope (TEM).Selected area diffraction pattern (SAED) and X-ray diffraction (XRD) confirm that the nanoparticles are comprised of metallic indium. An enhanced SERS and shell-isolated SERS activity from thin film of tryptophan molecules deposited on indium coated substrates were observed under 325nm UV excitation.Finite difference time domain (FDTD) method is employed to calculate the localized surface plasmon resonance (LSPR) wavelength for the obtained nanoparticle size of ~ 40nmas well as for silica-shell coated In0 nanostructures. FDTD calculations clearly show that an enhanced electromagnetic field can be generated aroundthebare as well as SiO2 coated indium substrates indicating that indium can act as a easy-to-use and effective contrast agent for UV-SERS.
9:00 PM - ED14.3.10
Precisely Size-Tunable Monodisperse Hairy Plasmonic Nanoparticles via Amphiphilic Star-Like Block Copolymers
Yihuang Chen 1 , Zhiqun Lin 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractThis study reports in-situ precision synthesis of monodisperse hairy plasmonic nanoparticles with tailored dimensions and compositions by capitalizing on amphiphilic star-like diblock copolymers as nanoreactors. Such hairy plasmonic nanoparticles comprise uniform noble metal nanoparticles intimately and perpetually capped by hydrophobic polymer chains (i.e., “hairs”) with even length. Interestingly, amphiphilic star-like diblock copolymer nanoreactors retain the spherical shape under reaction condition, and the diameter of the resulting plasmonic nanoparticles and the thickness of polymer chains situated on the surface of nanoparticle can be readily and precisely tailored. These hairy nanoparticles can be regarded as hard/soft core/shell nanoparticles. Notably, the polymer “hairs” are directly and permanently tethered to the noble metal nanoparticle surface, thereby preventing the aggregation of nanoparticles and rendering their dissolution in nonpolar solvents and the homogeneous distribution in polymer matrices with long-term stability. This amphiphilic star-like block copolymer nanoreactor-based strategy is viable and robust and conceptually enables the design and synthesis of a rich variety of hairy functional nanoparticles with new horizons for fundamental research on self-assembly and technological applications in plasmonics, catalysis, energy conversion and storage, bioimaging, and biosensors.
9:00 PM - ED14.3.11
In Situ Optical Spectroscopy and Electrodynamic Simulation Study of the Growth of Curved Plasmonic Nanocrystals
Fabrizio-Zagros Sadafi 1 4 , Christian Sauerbeck 1 3 , Lukas Pflug 2 4 , Bjoern Braunschweig 1 5 6 , Michael Stingl 2 5 6 , Robin Klupp Taylor 1 5 6
1 Institute of Particle Technology, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen Germany, 4 Graduate School "Advanced Materials and Processes", Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen Germany, 3 School of Advanced Optical Technologies, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen Germany, 2 Applied Mathematics 2, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen Germany, 5 Interdisciplinary Center for Functional Particle Systems, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen Germany, 6 Cluster of Excellence "Engineering of Advanced Materials", Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen Germany
Show AbstractFor nearly two decades there has been an intense search for versatile methods to produce plasmonic colloids with precise control over the optical resonance exerted through simple process parameters. The most easily synthesized systems, at least on laboratory scale, display a high degree of symmetry and include noble metal nanoshells, nanorods and nanocubes. Synthetic routes which lead to nanostructures with a greater degree of asymmetry than such systems are highly sought because the symmetry breakage would enable unique resonant modes to be achieved and tailoring of the nanostructures for certain applications e.g. theranostics or IR pigments. However, the scalable synthesis of asymmetric nanostructures would seem at first even more prohibitive than that of symmetric particles. Recently we have identified a simple liquid phase chemical approach to produce nanoscale curved metal patches on metal oxide or polymer core nano- and microparticles. The method, which avoids the templates, seeds or multiple processing steps normally associated with asymmetric nanostructure formation, relies on enrichment of metal species and other reactants at the core particle surface and thus delivers a kinetic preference for an isolated heterogeneous nuclei to form followed by surface conformal crystal growth. We have shown that under chosen process conditions leading to reaction limited or surface diffusion limited crystal growth, the morphology of the curved crystal patch can be tuned from radially symmetric to dendritic respectively. Since our approach can be used to make gold or silver patches on a range of different core particles having diameters greater than ~50 nm a wide range of possible plasmonic properties is available in this system. Besides their promise for optical applications, the plasmonic properties of the patches are a useful tool for understanding their own growth. This is especially pertinent because the formation of curved crystals has been rarely studied up till now. In this contribution we report on a study of the kinetics of curved silver patch growth making use of in situ optical UV/VIS/NIR spectroscopy and finite element method electrodynamic simulations. The latter were carried out for a wide range of silver patch coverages and thickness on silica core particles. The two primary features in the extinction spectra, a UV resonance at around 330 nm and a near IR resonance at around 1000 nm were observed to depend differently on the patch thickness and coverage. We acquired experimental optical extinction spectra of the growing silver patches using a fiber-coupled spectrometer. By extracting the trends in the UV and IR resonances during growth and making use of the library of electrodynamic simulations we could find a best fit for coverage/thickness combinations during much of the growth. This enabled kinetic details of the original crystal growth reaction to be elucidated.
9:00 PM - ED14.3.12
Gold Nanoparticle Plasmon Resonance in Near-Field Coupled Au NPs Layer/Al Film Nanostructure—Dependence on Metal Film Thickness
Oleg Yeshchenko 1 , Victor Kozachenko 1 , Antonina Naumenko 1 , Nataliya Berezovska 1 , Nataliya Kutsevol 1 , Vasyl Chumachenko 1 , Anatoliy Pinchuk 2
1 , National Taras Shevchenko University of Kyiv, Kyiv Ukraine, 2 Department of Physics and Energy Science, University of Colorado at Colorado Springs, Colorado Springs, Colorado, United States
Show AbstractA particularly interesting plasmonic system that recently is under study is that of metal NPs interacting with a metal film. This system has been predicted to display a lot of interesting optical phenomena caused by the coupling of the NPs with the film through the field of surface plasmons excited in the NPs. The study of extinction spectra of the metal NPs covered by a metal film with variable thickness gives the possibility to probe the dependence of coupling effects on the metal film thickness.
In present work, the light extinction spectra of layer planar Au NPs layer / Al film nanostructure have been measured. Two samples with polymer coated Au NPs (14 nm size) and bare Au ones (91 nm size) have been studied. The Al film thickness was varied in the range of 0–62 nm and 0–55 nm in these samples respectively. Effects of plasmonic coupling of Au NPs with Al film and an influence of the film thickness on the coupling have been studied quantitatively analyzing the dependences of spectral characteristics (magnitude, wavelength and width) of Au NPs SPR extinction peak on the film thickness. The main features of these dependences are SPR peak magnitude increase for polymer coated Au NPs, non-monotonical behavior of the magnitude for bare ones, as well as red shift and broadening of SPR at the increase of the Al film thickness. The mutual for both polymer coated and bare Au NPs physical mechanisms determining these dependences are coupling of the layer of Au NPs with Al film through the field of localized surface plasmons in Au NPs and the excitation of propagating surface plasmon polaritons in Al film through the light scattered by Au NPs. An additional mechanism actual for bare Au NPs is the non-radiative damping of SPR that is caused by the electrical contact between metal NPs and film.
The reported tuning of light extinction in layered nanosystem metal (Au) NPs / metal (Al) film, depending on the metal film thickness, is outstanding feature of such kind nanostructures that can be used for very simple and efficient tuning of their optical response in variety of nanophotonic applications.
Symposium Organizers
Radha Narayanan, Cesari and McKenna, LLP
Jingyi Chen, Univ of Arkansas
Svetlana Neretina, University of Notre Dame
Anatoliy Pinchuk, University of Colorado Colorado Springs
Symposium Support
MilliporeSigma
ED14.4: Designing Bimetallic Plasmonic Nanostructures
Session Chairs
Jingyi Chen
Svetlana Neretina
Wednesday AM, April 19, 2017
PCC North, 100 Level, Room 130
9:00 AM - *ED14.4.01
Crystal Phase-Controlled Synthesis of Novel Noble Metal Nanomaterials
Hua Zhang 1
1 , Nanyang Technological University, Singapore Singapore
Show AbstractIn this talk, I will summarize the recent research on the crystal phase-controlled synthesis of novel noble metal nanomaterials in my group. It includes the first-time synthesis of hexagonal-close packed (hcp) Au nanosheets (AuSSs) on graphene oxide, surface-induced phase transformation of AuSSs from hcp to face-centered cubic (fcc) structures, alternating hcp/fcc Au square-like plates from AuSSs, ultrathin Au nanowires containing hcp phase, synthesis of ultrathin fcc Au@Pt and Au@Pd rhombic nanoplates through the epitaxial growth of Pt and Pd on the hcp AuSSs, respectively, the first-time synthesis of 4H hexagonal phase Au nanoribbons (NRBs) and their phase transformation to fcc Au RNBs, the epitaxial growth of Ag, Pt, Pd, PtAg, PdAg, PtPdAg, Rh, Ir, Ru, Os and Cu on 4H Au NRBs to form the 4H/fcc Au@metal core–shell NRBs, and the synthesis of 4H/fcc-Au@metal sulfide core-shell NRB heterostructures. Currently, my group focuses on the crystal phase-based applications in catalysis, surface enhanced Raman scattering, waveguide, photothermal therapy, etc., which we believe are unique. Importantly, the concept of crystal-phase noble metal heterostructures is proposed.
9:30 AM - *ED14.4.02
Synthesis of Alloyed Nanoparticles with Mixed Concave-Convex Surfaces
Michelle Personick 1 , Melissa King 1
1 , Wesleyan University, Middletown, Connecticut, United States
Show AbstractNoble metal nanoparticles enclosed by high energy surface facets are promising catalytic materials due to the prevalence of under-coordinated surface atoms which can exhibit enhanced catalytic activity when compared to more planar, low-index surfaces. This promising catalytic activity has led to a recent focus on the development of syntheses for noble metal nanoparticles defined by either convex or concave high energy surfaces. By manipulating the relative reduction kinetics of gold and palladium precursors through the tailored addition of low concentrations of iodide ions during nanoparticle growth, we have synthesized complex gold-palladium alloyed nanostructures. These gold-palladium nanoparticles possess an unusual combination of both well-defined convex and concave surface features and are highly symmetric. Importantly, we find that the successful use of iodide as a shape-controlling agent to generate exotic nanostructures via this synthesis is due to the iodide-assisted reduction of palladium, particularly at the edge sites of the growing gold nanoparticles
10:00 AM - *ED14.4.03
Seeding Stellated Au-Pd Nanocrystals as Colloids with High Refractive Index Sensitivity
Sara Skrabalak 1
1 , Indiana University Bloomington, Bloomington, Indiana, United States
Show AbstractBimetallic nanoparticles display unique optical and catalytic properties that depend on crystallite size and shape, composition, and overall architecture. They may serve as multifunctional platforms as well. Unfortunately, many routes toward shape and architecturally controlled bimetallic nanocrystals yield polydisperse samples on account of the challenges associated with homogeneously nucleating a defined bimetallic phase by co-reduction methods. With Au–Pd as a model system, a set of design principles has been established for the colloidal synthesis of shape-controlled bimetallic nanocrystals by seed-mediated co-reduction (SMCR). This strategy is successful at synthesizing symmetrically stellated Au–Pd nanocrystals with a variety of symmetries and core@shell Au@Au–Pd nanocrystals. Using this toolkit, the light scattering and absorption properties of Au–Pd octopods, 8-branched nanocrystals, with octahedral symmetry could be tuned and were shown to be highly sensitive to changes in refractive index. This high sensitivity is achieved by lowering the dielectric dispersion at the nanocrystals at the resonant wavelength with internal or external atomic % Pd. To our knowledge, these NCs display the highest ensemble RIS measurement for colloids with LSPR maximum band positions ≤900 nm, and these results are corroborated with FDTD computations.
10:30 AM - ED14.4.04
A Pragmatic Approach to Gold Nanostars—Unique Design, Advanced Synthesis, and Novel Characterization
Ted Tsoulos 1 , Supriya Atta 1 , Huolin Xin 2 , Laura Fabris 1
1 , Rutgers University, Piscataway, New Jersey, United States, 2 , Brookhaven National Laboratory, Upton, New York, United States
Show AbstractGold nanostars (NS) have emerged as powerful nanostructures for surface enhanced Raman scattering (SERS) and MRI imaging, and promise to lead to exciting new devices driven by plasmonic hot electrons. For instance, in our SERS-based sensing experiments, we have shown that Au NSs can provide enhancement factors close to 1010, which are among the highest that have been achieved to date. However, the fundamental work necessary to truly enable the application of nanostars as imaging tags, sensors, or photocatalysts, is still scarce. Notably, the fundamental physical and optical parameters describing Au NSs, such as crystallographic structure, atom packing density, volume, surface area, extinction coefficients, have not yet been evaluated for all types of NSs, and synthetic protocols enabling the production of monodispersed suspensions of nanostars with narrow and clearly assignable plasmonic resonances are lacking.
Herein, we will report on our two-pronged study in which simulations and experiments have been employed jointly to design and synthesize highly monodispersed gold nanostars with finely tunable plasmonic resonances, to predict and assign their resonant modes, and to identify their fundamental physical and optical properties. In particular, we have determined volume, surface area, and extinction coefficient by first estimating them via a semi-empirical model and then confirming them with high-resolution TEM experiments, inclusive of STEM tomography. Furthermore, we have employed the reconstructed nanostar topography to calculate intensity and distribution of local scattered electric fields for the experimentally synthesized nanostars. Our results provide, for the first time, 1) advanced synthetic protocols to achieve highly monodispersed suspensions of nanostars with tunable morphology and resonances, 2) a realistic computational model describing their scattered electric fields, and 3) a practical method to easily estimate their fundamental physical and optical parameters. Taken together, these results will be important to render nanostars truly applicable.
10:45 AM - ED14.4.05
Plasmonic Nanostructures as Anti-Counterfeit Tags and Environmental Sensing Platforms
Alison Smith 1 , Rebecca Weiner 2 , Samantha Harvey 2 , Sara Skrabalak 2
1 , Naval Surface Warfare Center, Crane Division, Crane, Indiana, United States, 2 Chemistry, Indiana University, Bloomington, Bloomington, Indiana, United States
Show AbstractMetallic nanocrystals (NCs) have tunable plasmonic properties that depend on their size, shape, composition, and local environment. The implication of the latter is that these NCs are useful as refractive index (RI)-based sensors. We present metallic NCs as a multifunctional sensing platform by demonstrating that the far-field scattering of randomly deposited NCs serve as a physically unclonable optical function for anti-counterfeit applications in which the scattering patterns are easily produced yet impractical to replicate. The facile deposition method coupled with the intense scattering and optical response of metal NCs provide physically unclonable tags with the ability to serve as tamper-evident and aging labels (environmental sensors). Improving upon the environmental sensing capabilities of monometallic NCs, we demonstrate the ability to incorporate chemical selectivity through the external composition of bimetallic NCs and enhance their RI sensitivity (RIS) by increasing either the internal or external atomic %Pd in Au-Pd octopodal NCs with either Au or Pd interiors. These NCs display the highest ensemble RIS measurement to date for colloids with LSPR maximum band positions ≤ 900 nm in water making them excellent sensing platforms. Moving beyond the properties of single NCs, the assembly of colloidal nanostructures into ordered arrays is also appealing from both a production and an application stand point. Bottom-up fabrication provides scalability toward 2D and 3D structures that can exhibit unique, collective properties or project NC properties onto device-scale components. In identifying nanofabrication methods toward assembly of bimetallic NCs and subsequently investigating how the assembly composition affects the RIS and chemical selectivity, new multifunctional platforms (e.g. structural health monitors) should be possible with less conventional plasmonic metals.
11:30 AM - *ED14.4.06
Enriching the Ag Nanocrystals with Other Noble Metals
Dong Qin 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractSilver nanocrystals embrace fascinating optical properties known as localized surface plasmon resonance, which is essential to applications such as sensing and imaging. For example, Ag nanocubes embrace surface-enhanced Raman scattering (SERS) properties with enhancement factors up to 106 at visible excitation wavelengths for highly sensitive detection of chemical or biological species. Unfortunately, elemental Ag is highly susceptible to oxidation under conditions that involve oxidants, halide ions, and acids. Such chemical instability often results in changes to the morphology of Ag nanocrystals, particularly at corners and edges with high energies, and ultimately compromises their performance. One potential solution to improve the chemical stability of elemental Ag is to form alloys with a more stable metal (M: Au, Pd, and Pt) at the high-energy facets of Ag nanocrystals. However, it is often challenging to form Ag-M alloys by reducing their precursors simultaneously in a solution phase due to their substantial difference in reactivity. In this talk, I will report our recent developments in the selective deposition of the 2nd metal onto Ag nanocrystals for the generation of bimetallic core-frame and core-shell nanocrystals. I will demonstrate the combined plasmonic and catalytic properties of these bimetallic nanocrystals for monitoring the catalytic reactions by SERS.
12:00 PM - *ED14.4.07
Synthesis and Characterization of Pt−Ag Hollow Nanocrystals with Enhanced Catalytic Activity and Durability
Shutang Chen 1 , Jing Zhao 1
1 , University of Connecticut, Storrs, Connecticut, United States
Show AbstractBimetallic hollow nanostructures have become the most promising electrocatalysts for the commercialization of fuel cell technology due to their increased durability and utilization efficiency. In this study, Pt-Ag hollow nanocrystals were synthesized by physical/chemical treatment of Ag@Pt core@shell nanostructures using two different methods: thermal treatment induced surface segregation, and O2-assisted removal of Ag core. While the use of thermal treatment gives hollow nanocrystals of ~ 44 nm, the O2-assisted etching method yields spherical hollow nanocrystals with a size that can be controlled between ~5.8 nm and ~22.4 nm. The hollow Pt-Ag nanocatalysts exhibited enhanced specific activity towards oxygen reduction reaction and methanol oxidation reaction. Remarkably, 5.8 nm Pt-Ag porous structures with the interior and exterior catalytic surfaces exhibit drastically enhanced catalytic activity and durability. Even after 20,000 cycles of polarization, the shape, electrochemically active surface area, and specific activity of 5.8 nm hollow nanocataysts have no significant change. This work demonstrates a simple strategy for producing ultrasmall porous catalysts that can be potentially used as electro-catalysts in fuel cells.
12:30 PM - ED14.4.08
Gold Cubic Nanoboxes with Plasmonic Absorption in the Near-Infrared Region
Xiaojun Sun 1 , Kyle Gilroy 1 , Dong Qin 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractGold nanoboxes with hollow interiors and ultrathin wall thickness represent a new class of nanostructures that exhibit tunable plasmonic properties in near-infrared region. In this talk, we will present a facile route to the Au-based cubic nanoboxes with 2-nm wall thickness and well-defined openings at the corners. Specifically, we selectively deposited Au atoms onto the edges and side faces of Ag nanocubes with slight truncations at the corners for the generation of Ag@Au core-shell nanocubes. Because the Au deposition process involved the use an aqueous solution at pH=11, we believe that the Ag2O layers were formed at the corners of nanocubes owning to the release of Ag+ ions from nanocubes through a redox reaction between Au3+ and Ag. By dissolving the oxide patches in a weak acid, we successfully transformed the Ag@Au core-shell nanocubes to Au-based cubic nanoboxes by removing Ag interior using 3% H2O2. We demonstrated the feasibility of this strategy to produce Au nanoboxes as small as 20 nm for the outer edge length. We also elucidated the approaches to tuning the localized surface plasmon resonance (LSPR) properties of Au nanoboxes from 800 to 1200 nm by maneuvering the size and composition of the resultant nanostructures. Based on the discrete dipole approximation (DDA) calculations, we concluded that the extinction peak position was sensitive to the edge length and the wall thickness of nanoboxes. Additionally, we could simply adjust the edge length of nanoboxes to tailor the absorption and scattering cross sections. For instance, the absorption would completely dominate for the nanobox with an edge length of 20 nm, while scattering would arise with a contribution of 10% as the edge length was increased to 40 nm.
12:45 PM - ED14.4.09
Gold Nanotriangles Decorated with Superparamagnetic Iron Oxide Nanoparticles
Anna Roig 1 , Siming Yu 1 , Jordan Hachtel 2 , Miquel Torras 1 , Adria Gordillo 1 , Sokrates Pantelides 2 , Anna Laromaine 1 , Marti Gich 1
1 , Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Bellaterra Spain, 2 , Vanderbilt University, Nashville, Tennessee, United States
Show AbstractSimple approaches to synthesize multifunctional anisotropic plasmonic nanoparticles are of interest in several fields expanding from nanomedicine to catalysis. Microwave-assisted synthesis is a volumetric heating method that can be exploited to fabricate more complex heterostructures by promoting selective heating at desired sites. We will report on a straight-forward, fast, and bio-friendly microwave-assisted polyol route to synthesize gold nanotriangles decorated with a thin shell of iron oxide nanoparticles. The nanoparticles are superparamagnetic at room temperature and can self-assemble as a continuous layer at the liquid-air interfaces [1]. An in-depth structural and compositional characterization of the system will be presented as well as a method to remove the oxide nanoparticles to elucidate how the plasmonic properties of the nanotriangles are affected by the surface decoration [2]. Insights on the possible nucleation and growing mechanisms will be also provided.
[1] S.-M. Yu et al. Nanoscale, 2015, 7, 14039, DOI: 10.1039/C5NR03113C
[2] J. A. Hachtel, et al. Faraday Discuss., 2016,191, 215 , DOI: 10.1039/C6FD00028B,
ED14.5: Designing Nanomaterials for Plasmonics and SERS
Session Chairs
Radha Narayanan
Anatoliy Pinchuk
Wednesday PM, April 19, 2017
PCC North, 100 Level, Room 130
2:30 PM - *ED14.5.01
Shape-Controlled Synthesis of Copper Nanocrystals
Younan Xia 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractSilver and gold nanocrystals with controlled shapes have found widespread use in applications related to plasmonics, electronics, and SERS detection. However, there are only a few reports on the shape-controlled synthesis of copper nanocrystals due to the high reactivity of copper and thus its easy oxidation by the oxygen from air. In this talk, I will discuss our recent progress in the shape-controlled synthesis of copper nanocrystals, including nanocubes, pentagonal nanorods, and pentagonal nanowires. I will also discuss their surface plasmon resonance properties in correlation with their shapes or morphologies.
3:00 PM - ED14.5.02
Enhancing the Stability and Localized Surface Plasmon Resonance of Cu Nanostructures with Thin Silica Shells
Cameron Crane 1 , Feng Wang 1 , Jingyi Chen 1
1 , University of Arkansas, Fayetteville, Arkansas, United States
Show AbstractNanosized Au, Ag, and Cu, all exhibit localized surface plasmon resonance in the visible range, though due to the proclivity of Cu to oxidize, its visible extinction spectra tends to be short lived. This rapid oxidation is a hurdle to replacing more costly Ag and Au metals in systems utilizing the optical properties of these nanoparticles, such as surface enhanced Raman spectroscopy. By incorporating Cu nanoparticles and nanorods into a thin silica shell via a water in oil microemulsion, the extinction spectra of nano sized Cu cubes and rods, ~30 nm in diameter, were exceptionally well resolved and preserved in an aqueous environment. To our knowledge, this work is the first report of extinction spectra of uniform and well dispersed Cu-SiO2 suspensions, marking an improvement on solution based synthetic approaches and characterization of Cu-SiO2 core-shell structures. Using a combination of visible spectroscopy and dynamic light scattering, the effects of solution-phase particle agglomeration on the extinction spectrum, and the prevention of agglomeration via silica encapsulation, were studied. Most significantly, the distinct energy arising from the longitudinal plasmon of the nanorods could only be observed after encapsulation with SiO2. The absorption energies of Cu nanorods were modeled using a discrete dipole approximation approach, and matched quite well with our experimental results.
3:15 PM - ED14.5.03
Plasmonics at the Cluster Limit—Dielectric Sensing with DNA-Stabilized Silver Clusters
Stacy Copp 1 3 , Danielle Schultz 1 2 , Steven Swasey 1 , Alexis Faris 1 , Elisabeth Gwinn 1
1 , University of California, Santa Barbara, Santa Barbara, California, United States, 3 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 2 , National Institute of Standards and Technology, Gaithersburg, Maryland, United States
Show AbstractFew-atom silver clusters with rod-like geometries and high fluorescence quantum yields can be stabilized by DNA [1]. Now emerging in a number of sensing and photonic applications, much is still unknown about the mechanisms underlying the optical properties of these “AgN–DNA.” To better understand these mechanisms and to intelligently design applications, we investigate the effects of dielectric environment and cluster shape on electronic excitations of AgN–DNA. We first establish that the longitudinal plasmon wavelengths predicted by classical Mie-Gans (MG) theory agree with previous quantum calculations for excitation wavelengths of linear silver atom chains, even for clusters of just a few atoms. Application of MG theory to AgN–DNA with 400–850 nm cluster excitation wavelengths indicates that these clusters are characterized by a collective excitation process and suggests effective cluster thicknesses of ∼2 silver atoms and aspect ratios of 1.5 to 5. To investigate the sensitivity of these collective excitations to the surrounding medium, we measure the wavelength shifts produced by addition of glycerol. These are smaller than reported for much larger gold nanoparticles but easily detectable due to narrower line widths, suggesting that AgN–DNA may have potential for dielectric sensing in biomolecules at length scales of ∼1 nm [2]. This work has implications for understanding the lower size limits of nanoparticles sustaining plasmonic excitations and for biochemical sensing.
[1] E. Gwinn, D. Schultz, S. Copp, and S. Swasey, Nanomaterials 5, 180 (2015).
[2] S. M. Copp, D. Schultz, S. M. Swasey, A. Faris, and E. G. Gwinn, Nano Lett. 16, 3594 (2016).
4:30 PM - *ED14.5.04
Designing Nanomaterial Rattles for Plasmonics and SERS
Amanda Haes 1
1 , University of Iowa, Iowa City, Iowa, United States
Show AbstractDirectly detecting low concentrations of small molecules in biological and environmental samples is often limited by similar molecular structures and function of the target species as well as complex sample matrices. In addition, understanding molecular orientation is important in the detection of small molecules using SERS as adsorption processes can influence the measured signals. Herein, internally etched silica stabilized, gold coated silver nanoparticles are synthesized for their use as SERS substrates to ensure electromagnetic stability of the metal cores and surface accessibility for molecular adsorption and systematic SERS studies. The implications of molecular identity and concentration on molecular adsorption and SERS intensity are evaluated using localized surface plasmon resonance (LSPR) spectroscopy, SERS, and Langmuir adsorption isotherm modeling. Synergistic results suggest molecule-dependent tilt angles on the nanoparticle surfaces play a big role in small molecule quantification. These findings are confirmed through Langmuir adsorption isotherm modeling in which equilibrium constants and free energies of adsorption suggest that London dispersion force stabilization between the ligands and the metal surface induce these differences and the overall detectable SERS signals.
5:00 PM - *ED14.5.05
Challenges in Applying SERS to Quantitative Bioanalytical Measurements
Alexis Crawford 1 , Aleksander Skuratovsky 1 , Colin Young 1 , Marc Porter 1
1 , University of Utah, Salt Lake City, Utah, United States
Show AbstractSERS to Quantitative Bioanalytical Measurements
Alexis C. Crawford, a Aleksander Skuratovsky,b Colin C. Young,b and Marc D. Portera,b,c
aDepartment of Chemistry, bDepartment of Chemical Engineering, and cNano Institute of Utah University of Utah, Salt Lake City, UT, 84112, USA
Recent work has begun to realize the ability of surface-enhanced Raman scattering (SERS) to serve as a viable technique for quantitative analysis. This presentation describes the often overlooked impact of sampling error on the accuracy and precision of measurements when using SERS for the analysis of a sandwich-styled immunoassay. The assay architecture consists of a thin film gold substrate which is modified with a layer of capture monoclonal antibodies (mAbs) and extrinsic Raman labels (ERLs), which consist of a gold nanoparticle core (60 nm diameter) coated with a monolayer of a Raman reporter molecule and a layer of human IgG mAbs to tag the captured antigen. We will show from both theoretical modeling and experiments the importance of the sampling error that results from the small size of the focused laser spot used in SERS for sample interrogation. The presentation first examines the impact of sampling error by the construction and analysis of an antigenic random accumulation model; this is followed by an experimental study using two different laser spot sizes. Both sets of results indicate that the analysis of the assay substrate with a small laser spot can lead to a sampling error (i.e., undersampling) much like that found in instances in which the size of a measured soil sample fails to match accurately that of a larger, more representative geological sample. That is, the smaller the laser spot size, the larger probable deviation in the accuracy of the measurement and the greater the imprecision of the measurement. The possible implications of these results with respect to the general application of SERS for quantitative measurements are also briefly discussed.
5:30 PM - *ED14.5.06
Lipid Membrane Molecular Structures from Surface Enhanced Raman Scattering
James Matthews 1 , Cyna Shirazinejad 1 , Grace Isakson 1 , Steven Demers 1 , Jason Hafner 1
1 , Rice University, Houston, Texas, United States
Show AbstractGold nanostructures focus light to the nanometer scale at their surface due to resonant excitations of their free electrons called surface plasmons. In surface enhanced Raman scattering (SERS) the concentrated electromagnetic field amplifies Raman scattered light for nearby molecules. SERS has been widely studied as a platform for chemical and biological sensing, with a focus on creating metallic substrates that provide the greatest enhancements and therefore highest sensitivities. SERS also serves as a tool for the analysis of chemical interfaces. Since the near field decays rapidly with position and is aligned with the surface, the position and orientation of surface molecules are encoded in the SERS spectrum. However, SERS spectra are difficult to interpret quantitatively. Here we present an analysis framework that combines SERS spectra, Raman spectra, electromagnetic fields from numerical simulations, and derived polarizability tensors from time dependent density functional theory. This framework was applied to measurements on gold nanorods to reveal a 28 degree tilt in the surfactant bilayer surrounding the nanorods. It was also applied to fluid phase lipid bilayers surrounding the nanorods. In addition to the bilayer structure, the position and orientation of tryptophan was determined, in good agreement with nuclear magnetic resonance, optical dichroism, and molecular dynamics results. This method offers a new approach to analyzing lipid membrane molecular structure under ambient conditions, with microscopic quantities, and without molecular labels.
ED14.6: Poster Session II: Synthesis and Applications of Plasmonic Nanomaterials
Session Chairs
Jingyi Chen
Radha Narayanan
Svetlana Neretina
Anatoliy Pinchuk
Thursday AM, April 20, 2017
Sheraton, Third Level, Phoenix Ballroom
9:00 PM - ED14.6.02
Plasmonic Study of FeS2/Au and FeS2/Ag Nanoparticles
Rick Eyi 1
1 , University of Arkansas, Bedford, Texas, United States
Show Abstract
To improve the optical properties of the iron pyrite nanoparticles, the particles were coupled with metallic particles of Au and Ag. First, the gold nanocrystals were successfully synthesized and their UV-Vis was measured to confirm; then the FeS2 nanoparticles were then synthesized and dispersed in the same solvent as the gold nanoparticles, in this case the solvent was toluene. For the doping, the Au solution was added drop wise in the iron pyrite solution. The UV-Vis was again done after the coupling but no significant difference was noticed between the spectra before and after. It was speculated that the particle was too small to have an influence in the spectra of the combined particles. The PL spectroscopy of the combined particles was measured and compared with the spectrum of the particles before coupling. The PL saw an important decrease after the coupling. There could be an electron transfer between the iron pyrite and Au, but the conflicted values of the vacuum level of the iron pyrite did not allow a more affirmative answer. For synthesis of FeS2/Ag two methods were used. The first method was done by galvanic replacement of gold in the FeS2/Au nanoparticles by silver. For the second method after the synthesis of iron pyrite nanoparticles, silver precursor was introduced in the reactor to growth the metallic structure at the surface of the semiconductor. The absorption spectra of the coupled showed little difference from the uncoupled particles. The silver structure growth in the reactor with iron pyrite saw an increase, while the rest saw a decrease. The reason is thought to be that the metallic nanostructures were bigger and the enhancement in the absorption of the iron pyrite nanoparticles, cause by the strong scattering on light, overcame the traps that could have been introduced in the band gap.
Simulations of nanoparticles were done, to see, if the results could be reproduced by simulation. The simulation method used was finite difference frequency domain (FDFD). This method was used because of its ease to use and implement. The absorption spectra of Au, Ag and iron pyrite nanoparticles were simulated. The results were a little bit different to the experimental values but the trend seen in the simulations agrees with the results observed during the experiments. This was due, to the different approximations that were done during the simulation. Two things were taken from these simulations. First, the optical properties were increased after the coupling. The second thing is the plasmonic peak of iron pyrite is in the infrared region. The plasmonic position of the peak could be tuned by changing the size of the of the metallic part.
9:00 PM - ED14.6.03
Plasmonic Arrays of Metallic Nanoparticles Fabricated by Evaporative Patterning Using a Mask of Colloidal Silica Particles
Erika Rodriguez-Sevilla 1 , Cecilia Salinas 1 , Tannia Sandoval 1 , Erick Flores-Romero 1 2 , Ulises Morales 3 , Juan-Carlos Cheang-Wong 1
1 , Instituto de Física, Universidad Nacional Autónoma de México, México Mexico, 2 , Catedrático CONACYT, México Mexico, 3 Departamento de Química, Universidad de Guanajuato, México, Gto:, Mexico
Show AbstractWhen linked to a rough metal surface or to noble metal nanostructures, Raman active molecules interact with the localized electromagnetic field and take advantage of the plasmonic effects to achieve surface-enhanced Raman scattering (SERS), whose intensity may be many orders of magnitude larger than that of the incident light. In this work we combine a low-cost technique, nanosphere lithography (NSL), and thin film thermal evaporation to fabricate large arrays of metallic nanoparticles that can be used as efficient substrates for Raman-SERS molecular sensing. Spherical submicrometer-sized silica particles were prepared by sol-gel and deposited onto silica glass plates by means of a spin coater system. This silica monolayer is then used as a mask to create regular arrays of nanoscale features in the surface sample by a combination of nanosphere lithography and thin film thermal evaporation. In this case, an ordered array of metallic nanostructures is obtained on the substrate surface after the deposit of a 50 nm thick Ag or Au film and the removal of the silica mask. The size, size distribution and shape of both the colloidal silica mask and the array of Ag and Au nanoparticles were determined by scanning electron microscopy. The long range order of both the self-assembled monolayer of silica particles and the metallic nanoparticle arrays were characterized by a Fast Fourier Transform study. The plasmonic properties of the embedded metallic nanoestructures were characterized by optical absorption measurements. Finally, the use of the Au and Ag arrays as Surface-Enhanced Raman Spectroscopy substrates was evaluated while detecting rhodamine 6G molecules.
9:00 PM - ED14.6.04
Large-Scale and Size-Tunable Synthesis of Silver Nanoparticle via Stepwise Thermal Decomposition of Silver Oxalate toward Fabrication of Multi-Colored Plasmon Film
Takanari Togashi 1 , Natsuko Furusato 1 , Katsuhiko Kanaizuka 1 , Masato Kurihara 1
1 , Yamagata University, Yamagata Japan
Show AbstractLocal surface plasmon resonance (LSPR) has been used for various promising applications, such as surface enhanced Raman scattering, surface enhanced fluorescence, dye-sensitized solar cell, and biosensing devices. For these applications, the controlling of SPR band for desired wavelength is required to use wide band range of wavelength. Inter-particle plasmon coupling results in a red-shift of the LSPR band with further enhancement of the electromagnetic field. The magnitude of the LSPR peak shift is closely related to particle size. Here, we report the size-tunable synthesis of Ag NPs via thermal decomposition of Ag2C2O4 in a reaction medium highly concentrated with Ag (1.5 x10-1 to 2.4 x101 M) and fabricated Ag NPs dense monolayer by using ligand exchange reaction on a thiol-group modified glass substrate to tuning the inter-particle coupling LSPR band. The size of the Ag NPs was tuned via stepwise decomposition of Ag2C2O4 by modifying the method previously reported by us. The size of the NPs was easily tuned by controlling the addition amount of Ag2C2O4 and a high yield (~98%) of NPs was obtained using a small amount of alkylamine mixture. The sizes of the particles could be predicted from the diameter of the Ag seed crystal and the addition amount of Ag2C2O4. Ag NP films were fabricated on a thiol-modified glass substrate via a simple immersion technique for controlling the wavelength of the gap-mode plasmon band. Finally, the optical properties of the Ag NP dispersions and the fabricated Ag NP films were studied. The color of the Ag NP films changed because of the variations in the size of the Ag NPs.
9:00 PM - ED14.6.05
Gold Nanoparticle Plasmon Resonance in Electrodynamically Coupled Au NPs Monolayer/Dielectric Spacer/Al Film Nanostructure—Tuning by Variation of Spacer Thickness
Oleg Yeshchenko 1 , Victor Kozachenko 1 , Yurii Liakhov 1 , Anatoliy Pinchuk 2
1 , National Taras Shevchenko University of Kyiv, Kyiv Ukraine, 2 Department of Physics and Energy Science, University of Colorado at Colorado Springs, Colorado Springs, Colorado, United States
Show AbstractA particularly interesting plasmonic system that recently is under study is that of metal NPs interacting with a metal film. This system has been predicted to display a lot of interesting optical phenomena caused by the coupling of the NPs with the film through the field of surface plasmons excited in the NPs. The study of optical spectra (absorption, scattering) of the metal NPs separated controllably from a metal film using the dielectric spacer gives the possibility to probe the dependence of coupling effects on the distance between the NPs and film.
The studied plasmonic nanosystem is following. The dense 2D monolayer of Au NPs' was fabricated on glass substrate. Then the Au NPs' layer was covered by dielectric film of shellac. The thickness of shellac film was different in different parts of the sample varying in the range of 3–36 nm for sample S1 and 30–200 nm for sample S2. Above the shellac film, the aluminum film of 5 nm thickness was deposited. AFM gave the following Au NPs' layer parameters: NP size d = 90 nm, mean interparticle distance D = 140 nm. Thus, the studied Au NPs' layer is quite dense.
The extinction spectra of above mentioned three-layer nanostructure were measured at room temperature. We have obtained that coupling of surface plasmon resonance (SPR) in Au NPs with Al film leads to substantial enhancement (5.3 times) of the SPR magnitude and its appreciable red shift if comparing to the case of Au NPs without Al film. The increase of SPR magnitude at the decrease of spacer thickness from 200 nm to 70 nm is probably due to the following processes. First one is the excitation of propagating SP polaritons in the Al film through the near field of localized SPs in Au NPs. Second one is the redirection of the external incoming light as well as the light scattered by NPs by Al film back to layer of Au NPs with the subsequent absorption of the light by Au NPs. At thickness values lower than about 70 nm the decrease of dipolar SPR magnitude and the concomitant appearing of the quadrupolar SPR occur at the decrease of spacer thickness. This behavior is due to the hybridization of the dipolar and quadrupolar plasmons in the Au NP caused by the symmetry-breaking introduced by the presence of the Al film. As a result, the quadrupolar resonance acquires part of the “bright” character of the dipolar mode becoming easily visible on the absorption spectrum. Correspondingly, the dipolar resonance becomes darker, i.e. its magnitude decreases. The origin of observed appreciable (160 nm) red shift of SPR in Au NPs at the decrease of Al film thickness from 200 to 3 nm is the coupling of Au NPs and Al film through the plasmonic field. The decrease of spacing between Au NPs layer and Al film makes the coupling stronger that results in the red shift of SPR.
9:00 PM - ED14.6.06
Gold Cuboctahedral Nanoboxes with Plasmonic Absorption at Near-Infrared Wavelength
Junki Kim 1 , Dong Qin 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractGold (Au) nanostructures embrace unique optical properties, commonly referred to as localized surface plasmon resonance (LSPR), for a broad spectrum of applications. For solid Au nanoparticles with a spherical shape, it is feasible to manipulate their LSPR peaks from 520 to 580 nm by increasing the diameter from 20 to 80 nm. For most biomedical applications, however, it is essential to tailor the LSPR peaks to the near-infrared (NIR) between 800 and 1200 nm, in which soft tissues are highly transparent to enable deep penetration. One approach to shift the LSPR property to NIR is to fabricate Au-based nanostructures with hollow interiors. In this talk, we will present the fabrication of the Au cuboctahedral nanoboxes by depositing Au on Ag cuboctahedra, followed by the removal of Ag using 3% aqueous H2O2. These cuboctahedral nanoboxes could exhibit strong absorption in the NIR. Additionally, the etching of the {111} facets could introduce a cross shape, and such anisotropy would create more resonance peaks.
9:00 PM - ED14.6.07
Catalytically-Active Plasmonic Copper Nanostructures
Jingyi Chen 1 , Cameron Crane 1 , Ryan Manso 1
1 Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas, United States
Show Abstract
Copper is among the metals that exhibit surface plasmon in the visible region. As the size of Cu particles becomes smaller, they are susceptible to oxidation resulting in the loss of their plasmonic properties. Surface ligand/coating is one of the strategies that could slow down or may prevent the oxidation of the Cu particles thereby preserving their optical properties. In this work, different coating strategies are present and the optical properties of the resulting coated particles are compared. The coating strategies include monolayer ligand protection and silica coating on particle surface. Ligands with different terminated group are assessed to elucidate their bonding coordination abilities with Cu that influence the stability of the Cu particles. Silica coating with different thickness and porosity are investigated for their effects on the stability of the Cu nanoparticles. In addition, the catalytic activities of these coated Cu nanoparticles are evaluated for the Cu-catalyzed click reaction. Coupling with the spectroscopic techniques, the reaction mechanism is discussed to provide insight to this reaction.
9:00 PM - ED14.6.08
Ag-Au-Pt Cubic Nanoboxes and Their Plasmonic and Catalytic Properties
Zhiwei Zhang 1 2 , Dong Qin 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States, 2 , Xiamen University, Xiamen, Fujian, China
Show AbstractToday, it remains a daunting challenge to fabricate trimetallic nanocrystals with well-defined shapes and compositions. In this talk, we will present the selective deposition of Pt onto the edges of Ag@Au6L core-shell nanocubes for the generation of trimetallic nanocubes with an edge length of 40 nm. These nanocubes embrace excellent SERS activities at both visible and near infrared excitation wavelengths. Upon removal of Ag, Ag-Au-Pt cubic nanoboxes with thickness of 2 nm can be produced. These nanoboxes exhibit strong plasmonic properties at near-infrared wavelength, together with a catalytic activity in accelerating the reduction of nitrophenol by NaBH4.
9:00 PM - ED14.6.09
Large Scale Synthesis of Ag Nanoparticles and Their Applications in Catalysis
Xiaojun Sun 1 , Xuan Yang 1 , Dong Qin 1
1 , Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractAg nanoparticles embrace fascinating plasmonic properties for a spectrum of desired applications. However, it remains a daunting challenge to synthesize Ag nanoparticles in a quantity up to 1 gram. In this talk, we will present a facile synthesis that relies on the co-reduction of HAuCl4 and AgNO3 by a reducing agent to produce 1 gram of Ag nanoparticles with a reaction time of 5 min under ambient condition. We suspected that the higher reduction potential of AuCl4- would allow the production of Au atoms with which Ag+ ions would be reduced more easily into Ag atoms via under potential deposition, followed by their deposition onto Au seeds for the generation of Ag nanoparticles with a uniform size of 50 nm. We used these Ag nanoparticles as templates for the selectively deposition of Pt atoms. Upon the removal of Ag, we produced Pt-Ag nanocages in 70 mg. We demonstrated that these Ag-Pt nanocages represent a new Pt-based catalyst with enhanced mass activity for oxygen reduction reaction.
9:00 PM - ED14.6.10
Resonant Coupling between Molecular Vibrations and Localized Surface Plasmon Resonance of Faceted Metal Oxide Nanocrystals
Ajay Singh 1 2 , Ankit Agrawal 2 , Delia Milliron 2
1 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 2 The McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas, United States
Show AbstractColloidally synthesized doped metal oxide nanocrystals has recently got great scientific attention for their ability to manipulate the localized surface plasmon resonance (LSPR) by varying their composition. Due to highly variable carrier concentration in these material, it enables plasmon frequency over entire infrared region and has facilitated a new class of tunable plasmonic materials with potential applications in the fields of photocatalysis, sensors, smart windows and surface enhanced Infrared absorption spectroscopy (SEIRA). In particular, SIERA exploits the signal enhancement to increase the sensitivity of spectroscopic feature exerted by the plasmon resonance of nanostrucrtured/nanocrystal thin films. To date, most of the studies based on plasmon- molecular vibration coupling have been focused on the plasmonic metal nanocrystal. Here, we will present the doped Indium Oxide as prototypical material. Dopant driven nanocrystal shape evolution and thereby plasmon property of colloidally synthesized octahedron , cubo-octaherdron and cubic will be emphasized. We will further describe the size dependent plasmon property of doped Indium Oxide, map the near field enhancement property of single cubic nanocrystals via EELS and quantify both far field and near field plasmon property via COMSOL electromagnetic simulations. Furthermore, we show how C-H molecular bonds (2800-3200 cm-1) couples to periodic film doped Indium Oxide nanocrystal both experimentally and computationally. This development of metal oxide plasmonic platform for molecular sensing could lead to easy to make, electrically tunable surface enhanced infrared absorption spectroscopy substrates.
9:00 PM - ED14.6.11
Au Coated SPIO-Core Nanoparticles with Tunable Shell Thickness to Promote Low-Level Laser Therapy at High Photothermal Conversion Efficiency
Muzhaozi Yuan 1 , Ya Wang 1 , Jon Longtin 1 , David Hwang 1
1 Mechanical Engineering, Stony Brook University, Stony Brook, New York, United States
Show AbstractIn this paper, we report a facile synthesis of Au coated SPIO-core nanoparticles (NPs) with tunable shell thickness (1.5 nm to 8.5 nm) and high photothermal-efficiency (0.93) at low-level laser power density (~ 100 mW, 4 mm). A seed growth method using citrate acid as reducing agent was proposed to reduce Au3+ to Au at the surface of SPIO NPs (10 nm) that serve as original seeds. The thickness of Au coatings was tuned by moderating the composition of the reactants and other reaction conditions. This refined synthesis method facilities the easy tuning of plasmonic properties of SPIO-Au core shell nanomedicines to promote high light-to-heat conversion efficiencies, demanded by different hyperthermia treating conditions. Transmission electron microscope (TEM) images of the SPIO-Au NPs reveal the uniform quasi-spherical nanostructure and the absence of aggregation. The inductively coupled plasma mass spectrometer (ICP-MS) analysis demonstrates the successful formation of SPIO-Au NPs at predicted sizes and concentrations. UV-Vis light absorption spectra verify the slightly red shift of the surface plasmon resonance band with the increase of the thickness of Au coating. Based on thermal energy balance equations, photothermal conversion efficiencies of as-synthesized SPIO-Au NPs demonstrate the high light-to-heat conversion efficiency (0.93, 8 nm Au coating, 70 ppm) in comparison to their Au NP counterparts in literature on the similar size and concentration scales. The studies pertaining to tunable Au-coating-thickness, temperature measurement and photothermal analysis are crucial for clinical applications in high-performance low-level laser therapy on well-controlled tumor cell removal.
Symposium Organizers
Radha Narayanan, Cesari and McKenna, LLP
Jingyi Chen, Univ of Arkansas
Svetlana Neretina, University of Notre Dame
Anatoliy Pinchuk, University of Colorado Colorado Springs
Symposium Support
MilliporeSigma
ED14.7: Plasmon-Assisted Processes
Session Chairs
Radha Narayanan
Anatoliy Pinchuk
Thursday AM, April 20, 2017
PCC North, 100 Level, Room 130
9:00 AM - *ED14.7.01
Controlling Single Atoms and Molecules in Ultrasmall Plasmonic Nanocavities
Jeremy Baumberg 1
1 , University of Cambridge, Cambridge United Kingdom
Show AbstractTrapping light into gaps between noble metal nanostructures yields intense local amplification of the optical field, which opens up new regimes of chemical analysis. The largest enhancements come from the smallest nano-gaps, and recently we have devised a whole class of approaches yielding robust, low-cost, reproducible, sub-nm gaps that produce exceptional performance for surface-enhanced-Raman scattering, capable of looking at down to individual molecules over periods of many minutes. We show that we are also able to optically control the position of individual atoms, producing optical cavities with volumes much less than a nm on each side, a billion times smaller than the wavelength scale for visible light. This enables us to watch individual bonds between molecules in real time. We are also able to explore larger-scale robust nanoassembly to track neurotransmitters in real biofluids such as urine without biofouling, and are exploring the bioscreening that this is capable of delivering.
Coupling between plasmonic nano-components generates strongly red-shifted resonances combined with intense local field amplification on the nanoscale. This allows directly seeing molecules as well as excitations in semiconductors. We have recently explored plasmonic coupling which can be tuned dynamically, through reliable bottom-up self-assembly. The crucial aspect of these systems is the extreme sensitivity to separation, and how quantum tunneling starts to be directly seen at room temperature in ambient conditions. We recently demonstrated how quantum plasmonics controls the very smallest space that light can be squeezed into. We also demonstrate the possibility to track few molecules using the extreme enhancements. We show how the new generation of 2D semiconductors can couple to such nano-scale gaps utilizes our nanoparticle on mirror geometry. We find that changing just a single atom on each molecule of a self-assembled monolayer can shift the plasmon by over 50nm, and produce surprising vibrational signatures.
[1] Nature 491, 574 (2012); Revealing the quantum regime in tunnelling plasmonics,
[2] Nano Lett 13, 5033 (2013); Controlling sub-nm plasmonic gaps using graphene
[3] ACS Nano 9, 825 (2014); Monitoring Morphological Changes in 2D Monolayer Semiconductors …
[4] Nano Letters 15, 669 (2015); Nano-optics of molecular-shunted plasmonic nanojunctions
[5] Science Reports 4, 5490 (2014); Watching individual molecules flex within lipid membranes using SERS
[6] Scientific Reports 4, 6785 (2014); Quantitative multiplexing with nano-self-assemblies in SERS
[7] Nano Lett 13, 5985 (2013); In-situ SERS monitoring of photochemistry within a nano-junction reactor
[8] Nano Letters 15, 7452 (2015); Controlling Nanowire Growth by Light
[9] Nature 535, 127 (2016); Single-molecule strong coupling at room temperature in plasmonic nanocavities
9:30 AM - *ED14.7.02
Plasmon-Assisted Electrochemical Synthesis
Martin Moskovits 1
1 , University of California, Santa Barbara, Santa Barbara, California, United States
Show AbstractIn the near future, when we manage to wean ourselves off fossil fuels, we will also need to develop sustainable alternatives, preferably ultimately based on solar conversion, for the petrochemicals that currently provide us with our polymers and plastics, solvents, pharmaceuticals, among our many other chemical necessities. At that point in time, solar electricity will likely have become the dominant component of our electrical supply, so that the price of electricity will have decreased to record levels especially during daylight hours when supply outpaces demand. This, in turn will encourage the formation of industries that capitalize on cheap electricity to create valuable chemical products electrochemically, as a more valuable option to passive storage. Even then, one might profitably look for solar assisted syntheses of high value organic molecules from high-energy carbon sources such as CO2 – either directly through artificial photosynthesis, or by combining electrochemistry with photocatalysis to improve the yield of redox processes, as we recently showed for the catalytic decomposition of formic acid, whose activation energy was dramatically reduced through the action of plasmonically generated hot electrons and holes in Pd nano-sheets, which increased the reaction’s room-temperature rate constant by a (record) factor of 100 [Wu et al, Adv. Phot. Mater. 2016, 4, 1041–1046].
By judiciously shaping metal nanoparticles, one can create plasmonic systems that absorb sunlight over much of its UV-Visible spectrum. Moreover, it has been known for many years that almost any nanostructured metal has plasmonic properties, including ones, such as Pd that function both as efficient plasmonic absorbers and catalysts, and earth-abundant plasmonic materials such as Cu and Ni. By so doing solar energy will have potentially been harnessed in two ways: by creating abundant electrical power to drive electrochemical syntheses of organic molecules that can function as surrogates for platform molecules currently obtained from petrochemicals; and as a catalytic strategy whereby thermally driven chemical processes can be accelerated through the intermediacy of plasmon mediated hot electrons and holes.
10:00 AM - *ED14.7.03
Plasmon Induced Catalysis
Peter Nordlander 1
1 , Rice University, Houston, Texas, United States
Show AbstractPlasmons can serve as efficient generators of hot electrons and holes that can be exploited to control chemical reaction and induce phase changes in nearby materials. The physical mechanism for plasmon-induced hot carrier generation is non-radiative plasmon decay. Non-radiative plasmon decay is a quantum mechanical process in which one plasmon quantum is transferred to the conduction electrons of the nanostructure by excitation of an electron below the Fermi level into a state above the Fermi level but below the vacuum level. I will discuss recent applications photocatalysis, and in particular, how plasmonic antennas and transition metal catalysts can be combined in antenna/reactor geometries for enhanced efficiency and selectivity photocatalysis.
10:30 AM - ED14.7.04
Spatially Mapping the Reactivity of Plasmonic Nanoantennas
Emiliano Cortes 1 , Wei Xie 2 , Javier Cambiasso 1 , Adam Jermyn 3 , Ravishankar Sundararaman 3 , Prineha Narang 3 , Sebastian Schluecker 2 , Stefan Maier 1
1 , Imperial College London, London United Kingdom, 2 , University Duisburg-Essen, Essen Germany, 3 , California Institute of Technology, Pasadena, California, United States
Show AbstractNanoscale localization of electromagnetic fields near metallic nanostructures underpins the fundamentals and applications of plasmonics. [1] The unavoidable energy loss from plasmon decay, initially seen as a detriment, has now expanded the scope of plasmonic applications to exploit the generated hot carriers. [2] However, quantitative understanding of the spatial localization of these hot carriers, akin to electromagnetic near-field maps, has been elusive.
We present experimental and theoretical results of hot-electron driven reactivity mapping with nanometre resolution. We use the ability of hot electrons to locally reduce the terminal group of a self-assembled molecular layer that covers the surface of a nanoantenna. This modification is spatially localized using 15 nm nanoparticles (NPs) specially designed to react with the converted molecules only (see scheme). SEM imaging is used to record the position of the reporter-NPs after different time periods of light illumination and hence plasmon excitation, thus progressively mapping the reactivity of the nanoantennas. Geometry-dependent differences have been observed between Ag bow-ties and rounded Ag dimer antennas. We give physical insight into the experimentally observed spatial reactivity distributions with the aid of an efficient computational technique that we developed to predict hot carrier transport with spatial and energy resolution in complex plasmonic nanostructures from first principles [3]. Our results are essential to understand the efficiency of plasmonic energy conversion and plasmonic hot carrier extraction using molecular species.[3,4]
[1] Halas, N.J., Lal, S., Chang, W.-S., Link, S., Nordlander, P. Plasmons in Strongly Coupled Metallic Nanostructures. Chemical Reviews 111, 3913-3961 (2011).
[2] Linic, S., Christopher, P., Ingram, D.B. Plasmonic-metal nanostructures for efficient conversion of solar to chemical energy. Nat Mater 10, 911-921 (2011).
[3] Cortés, E., Xie, W., Cambiasso, J., Jermyn, A. S., Sundaraman, R., Narang, P., Schlücker, S., Maier, S. A., “Plasmonic hot electron transport drives nano-localized chemistry”, Nat. Comm. 8 (2017).
[4] Xie, W. & Schlücker, S. “Hot electron-induced reduction of small molecules on photorecycling metal surfaces”, Nat. Comm. 6 (2015).
10:45 AM - ED14.7.05
Polymer-Assisted Tuning of Surface Plasmons—From Applications to Fundamental
Tao Ding 1 , Jeremy Baumberg 1
1 , Cambridge University, Cambridge United Kingdom
Show AbstractThe complicated interactions between soft polymers and hard colloids are always intriguing and sometimes difficult to understand. More and more recent researches have shown that proper decoration of colloidal particles with polymers can lead to complicated self-assemblies via hydrophobic interactions, electrostatic interactions and even supramolecular bonding.1 The gold/poly(N-isopropyl acrylamide) (Au-PNIPAM) is a typical hybrid system that has been strongly investigated in the last decade.2 Our recent findings have shown that it not only builds nice tuning system for plasmons,3,4 but also generates large forces within μs for nanoactuation,5 which makes us wondering and revisiting this old but puzzling system.6
References
Klinkova, A.; Choueiri, R. M.; Kumacheva, E., Self-Assembled Plasmonic Nanostructures. Chem. Soc. Rev. 2014, 43, 3976.
Gibson, M. I.; O'Reilly, R. K., To Aggregate, or Not to Aggregate? Considerations in the Design and Application of Polymeric Thermally-Responsive Nanoparticles. Chem. Soc. Rev. 2013, 42, 7204.
Ding, T.; Rüttiger, C.; Zheng, X.; Benz, F.; Ohadi, H.; Vandenbosch, G.A.E.; Moshchalkov, V. V.; Gallei, M.; Baumberg, J. J., Fast Dynamic Color Switching in Temperature-Responsive Plasmonic Films, Adv. Opt. Mater., 2016, , 4, 877.
Ding, T.; Rudrum, A. W.; Herrmann, L. O.; Turek, V.; Baumberg, J. J., Polymer-Assisted Self-Assembly of Gold Nanoparticle Monolayers and Their Dynamical Switching, Nanoscale, 2016, 8, 15864.
Ding, T.; Valev, V. K.; Salmon, A. R.; Forman, C. J.; Smoukov, S. K.; Scherman, O. A.; Frenkel, D.; Baumberg, J. J., Light-Induced Actuating Nanotransducers. Proc. Nat. Aca. Sci. 2016, 113, 5503.
Ding, T.; Turek, V.; Martin, S. B.; Cormier, S.; Baumberg, J. To be submitted.
11:30 AM - *ED14.7.06
Sensitivity of Plamonic Metal Nanoparticles and the Application in Polymer Sensing
Guoliang Liu 1 , Assad U. Khan 1
1 , Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States
Show AbstractIn this presentation, we will present our recent progress on the utilization of plasmonic nanoparticles in polymer sensing. Currently the synthesis of plasmonic nanoparticles for sensing mostly focuses on the shape because it is believed that nanoparticles with sharp tips provide higher sensitivities than those without. Herein, by measuring and analyzing the sensitivities of more than 74 types of nanoparticles of various shapes, sizes, and compositions, we found that, contrary to this common belief, the correlation between shape and sensitivity is much weaker than that between aspect ratio and sensitivity. Among all the parameters investigated here including size, shape, composition, aspect ratio, cross-sectional area, and initial plasmonic resonance frequency, the aspect ratio is the key parameter that controls the nanoparticle sensitivity. Other parameters have much less influence on the nanoparticle sensitivity to refractive index changes. Based on this important finding, we selected Ag nanodisks as sensors to probe the kinetics of polymer brush formation. Unitizing the unique plasmonic properties of Ag nanodisks, we demonstrated in situ the three-regime kinetics of polymer brush grafting process, and importantly, for the first time we experimentally revealed the cause of a latent regime in the process of polymer brush grafting onto a surface.
12:00 PM - *ED14.7.07
Colloidal Gold Nanoplates and Their Plasmonic Properties
Jianfang Wang 1
1 , The Chinese University of Hong Kong, Shatin Hong Kong
Show Abstract
Noble metal nanoplates (NPLs) possess an intriguing geometry, and are nearly single-crystalline. Their large, atomically flat, single-crystalline surface allows for easy molecular functionalization. Moreover, the in-plane dipolar plasmon resonance of metal NPLs is strong and highly sensitive to the refractive index of the surrounding environment. Due to the sharp corners and edges, their local electric field enhancements derived from the in-plane dipolar plasmon resonance are very large. The high crystallinity also remarkably alleviates plasmon damping caused by electron scattering at grain boundaries and defect sites. Because of these attractive features, plasmonic metal NPLs have found a wide range of technological applications, such as biological sensing, plasmonic nanocircuits, and plasmon-enhanced spectroscopy. Several methods have been developed for the synthesis of high-quality colloidal Ag NPLs. However, the synthesis of colloidal Au NPLs in controllable uniform sizes and with their plasmon adjustable to the visible region has remained challenging.
We have realized the control of the plasmon wavelength of Au NPLs from the near-infrared to visible region. Our method combines the purification and atom migration of triangular Au NPLs together with anisotropic overgrowth and mild oxidation. Throughout the rounding process, the NPLs get thicker while their particle volumes remain unchanged. Anisotropic overgrowth converts the circular Au NPLs into hexagonal Au NPLs, where the thickness of the hexagonal NPLs can be well controlled in the range of 10-50 nm by simply varying the Au precursor amount. Moreover, circular Au NPLs, which are two-dimensional counterparts to three-dimensional Au nanospheres, can be produced in varying diameters and thicknesses through anisotropic oxidation of the hexagonal Au NPLs.
We have further carried out systematic studies about the effects of substrates with distinct dielectric functions on the plasmonic properties of Au NPLs, as well as about the plasmon coupling in heterodimers made of Au NPLs and Au nanospheres. The presence of a substrate causes plasmonic shifts as well as the appearance of new plasmon modes. The plasmonic shifts and the emergence of new plasmon modes are found to be dependent on the particle shape of Au nanocrystals and in turn on the fractional particle surface area that is in contact with the supporting substrate. A giant spectral shift of more than 300 nm is obtained for Au NPLs. Moreover, silicon substrates induce the emergence of Fano resonance for Au NPLs. The Fano resonance is found to become stronger as the thickness of Au NPLs is decreased. Moreover, the plasmon coupling in the Au NPL-nanosphere heterodimers induces strong Fano resonance, with its dip reaching down to the background level.
12:30 PM - ED14.7.08
Immobilized Gold Core-Satellite Nanostructures for Highly Sensitive Refractive Index and Vapor Sensors
Kensuke Akamatsu 1 , Kentaro Ode 1 , Yohei Takashima 1 , Takaaki Tsuruoka 1
1 , Konan University, Kobe Japan
Show AbstractDiscrete nanostructures of metal nanoparticles, such as dimers, trimers, chains, and satellites, exhibit electrical and optical properties that are based on localized surface plasmon resonance (LSPR) and are often very different from the properties of their isolated forms due to electronic interactions between adjacent nanoparticles. The LSPR wavelength can be tuned by controlling the size, spacing, symmetry, and orientation of the nanoparticles with respect to one another. Therefore, these plasmonic nanostructures have been of great interest for optoelectronic, photonic, and plasmonic applications. Core-satellite nanostructures are one of the most effective nanostructures for optical sensing because they have the highest number of coupled pairs of nanoparticles per single discrete nanostructure. In this contribution, we report the fabrication of high-purity satellite nanostructures made of differently sized spherical gold nanoparticles immobilized on glass substrates and their optical properties as highly sensitive refractive index sensors that can be used to detect various organic liquids and vapors. This type of nanostructure on a substrate is effective for refractive index-based sensor chips utilizing various detection technologies, because the nanostructures are immobilized on the substrates so that (1) any affinity of the nanostructure surface with the surrounding medium to be detected is unimportant (because no aggregation occurs), (2) immobilized nanostructures can be used not only for sensing liquids but also for vapors or gasses, and (3) the chips are reusable. The increased number of coupled SPR pairs, which is controlled simply by adjusting the number of satellite nanoparticles connected to cores, gives rise to a higher sensitivity to various organic liquids and vapors, without requiring a refractive index transducer around the metal nanostructures. Moreover, the systematic approach used to optimize particle diameter, the diameter ratio between core and satellite nanoparticles, and the number of satellites make this nanostructure an ideal platform for investigating how these structural variables impact plasmonic properties and sensing performance in a wide range of applications such as biomolecular sensing and/or environmentally toxic vapor concentration measurements.
12:45 PM - ED14.7.09
Precision Plasmonics with Ideal and Non-Ideal Dimers of Noble Metal Nanoparticles—Theory and Experiment
Jun Hee Yoon 1 , Florian Selbach 1 , Sebastian Schluecker 1
1 , University of Duisburg-Essen, Essen Germany
Show AbstractDimers of noble metal nanoparticles are the simplest system in which plasmonic coupling occurs. Theoretical predictions are typically based on idealized structures such as dimers of spheres. Here, we present, for the first time, the synthesis of such ideal dimers with distance control at the level of single chemical bonds. Correlative microscopic and microspectroscopic charaterization at the single-particle level shows the excellent uniformity of their plasmonic properties. In contrast, dimers of non-spherical particles exhibit a much higher heterogeneity and in particular blue-shifted longitudinal plasmon peaks. We represent results from FDTD calculations on such non-ideal dimers, which highlight the role of gap morphology.
ED14.8: Non-Precious Material Plasmonics
Session Chairs
Radha Narayanan
Anatoliy Pinchuk
Thursday PM, April 20, 2017
PCC North, 100 Level, Room 130
3:00 PM - *ED14.8.02
Molecular Plasmonics—Graphene Plasmonics at the Picometer Scale
Naomi Halas 1
1 , Rice University, Houston, Texas, United States
Show AbstractIt has been demonstrated that graphene plasmons can be tuned across the infrared by spatial and electronic confinement. The identification of a general class of plasmonic excitations in systems containing only a few dozen atoms- polycyclic aromatic hydrocarbon (PAH) molecules- permits us to extend this versatility into the visible and ultraviolet. We experimentally demonstrate the existence of molecular plasmon resonances in the visible for ionized PAHs, which we reversibly switch by adding, then removing, a single electron from the molecule. The charged PAHs display intense absorption in the visible regime with geometrical tunability analogous to the plasmonic resonances of much larger nanographene systems. We also use the switchable PAH plasmon to demonstrate a low-voltage, multistate electrochromic device.
3:30 PM - ED14.8.03
Precise Control over the Morphology and Dopant Distribution in Colloidal Metal Oxide Nanocrystals
Ajay Singh 1 , Amita Singh 1 , Delia Milliron 2
1 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 2 The McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas, United States
Show AbstractColloidal synthesis of doped metal oxide nanocrystals provides a great opportunity and easy route to generate materials that has unique optoelectronic properties with promising applications such as smart windows, displays, sensing and photo-catalysis etc. By introducing the free carriers with different type of dopants (n- or p-type) in the metal oxide nanocrystals, their surface plasmon resonance can be tuned precisely from near IR to mid-IR range. Similarly like metals, the optical response of plasmonic metal oxide nanocrystals can be manipulated by controlling the shape, size of the nanocrystal and free electron concentration. The effect of nanocrystal shape and size on the enhancement of their local electrical field strength and surface plasmon resonance have paved the way for new technologies and better sensing opportunities. The sharp faceted nanocrystals exhibit enhanced electric fields at corners and edges, which give us an opportunity to explore different morphologies of the NC for sensing application. Here, we will be presenting a solution route to synthesize plasmonic metal oxide nanocrystal (doped Indium Oxide) with defined shape, size and radial distribution of dopant in the nanocrystals. Also, with co-doping (cation, anion or both) in these nanocrystals, we can shift the surface plasmon resonance to higher energies and can also influence the shape of the nanocrystals. Further, we will present near field enhancement property of single nanocrystals via EELS mapping and quantify both near field and far field plasmon property via COMSOL electromagnetic simulations.
3:45 PM - ED14.8.04
Magnesium Plasmonic Nanoparticles in Water
Hyeon-Ho Jeong 1 2 , Andrew Mark 1 , Peer Fischer 1 3
1 , Max Planck Institute for Intelligent Systems, Stuttgart Germany, 2 Institute of Materials, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne Switzerland, 3 Institute for Physical Chemistry, University of Stuttgart, Stuttgart Germany
Show AbstractA plasmonic resonance in the UV promises entirely new possibilities in conjunction with molecular sensing, as most organic molecules show resonances in the UV.1 Aluminium (Al) nanoparticles are therefore currently being investigated for UV plasmonics.2 However, theory predicts that magnesium (Mg) provides both a substantially higher far-field absorption efficiency and a higher near-field electric field enhancement (highest in the UV).3 In conjunction with its plasmonic performance, Mg also possesses several other advantages; it is abundant, biocompatible, and lightweight (two-thirds lighter than Al).4 Nevertheless, it appears that Mg nanoparticles are so far not investigated for UV plasmonics in water. One major challenge is the fabrication of such structures and their stability once they are transferred to an aqueous environment. Here, we report the successful fabrication of Mg colloids5 as well as their corrosion protection6 and use as refractive index sensors.7
We demonstrate that colloidal solutions of Mg nanoparticles in the form of nanohelices give rise to a large extinction and chiroptical response in the UV and are therefore extremely promising for plasmonic sensing applications. A physical shadow growth method, which we reported in the earlier paper,8 is used to grow large-area arrays of Mg nanostructures. The particles then subjected to a coating procedure which ensures their stability for applications in water. We discuss how the chiral shape of the Mg nanocolloids enables high LSPR enhancements and thus permits new sensing tasks in complex fluids. In particular, we show that the refractive index dispersion of a small molecule in the UV gives rise to correspondingly larger plasmonic resonance shifts than in the visible.
1. M. W. Knight, N. S. King, L. Liu, H. O. Everitt, P. Nordlander and N. J. Halas, ACS Nano, 2014, 8, 834-840.
2. K. M. McPeak, C. D. van Engers, S. Bianchi, A. Rossinelli, L. V. Poulikakos, L. Bernard, S. Herrmann, D. K. Kim, S. Burger, M. Blome, S. V. Jayanti and D. J. Norris, Advanced Materials, 2015, 27, 6244-6250.
3. J. M. Sanz, D. Ortiz, R. Alcaraz de la Osa, J. M. Saiz, F. González, A. S. Brown, M. Losurdo, H. O. Everitt and F. Moreno, The Journal of Physical Chemistry C, 2013, 117, 19606-19615.
4. L.-Y. Chen, J.-Q. Xu, H. Choi, M. Pozuelo, X. Ma, S. Bhowmick, J.-M. Yang, S. Mathaudhu and X.-C. Li, Nature, 2015, 528, 539-543.
5. H.-H. Jeong, A. G. Mark and P. Fischer, Chemical Communications, 2016, 52, 12179-12182.
6. H.-H. Jeong, M. Alarcon-Correa, A.G. Mark, K. Son, T.-C. Lee, and P. Fischer, Corrosion protection of nanoparticles (In preparation).
7. H.-H. Jeong, A. G. Mark, M. Alarcon-Correa, I. Kim, P. Oswald, T.-C. Lee and P. Fischer, Nature Communications, 2016, 7, 11331.
8. A. G. Mark, J. G. Gibbs, T.-C. Lee and P. Fischer, Nature Materials, 2013, 12, 802-807.
4:30 PM - *ED14.8.05
Probing and Manipulating Resonant Nanostructures with Chiral Light
Mikael Kall 1
1 , Chalmers University of Technology, Goteborg Sweden
Show AbstractThree-dimensional chiral plasmonic nanostructures have been shown to be able to dramatically boost photon-spin selective light-matter interactions, potentially leading to novel photonics, molecular spectroscopy, and light-harvesting applications based on circularly polarized light. But even nanostructures that are intrinsically achiral can be made to preferentially couple to right-handed or left-handed light, an effect known as extrinsic chirality. Moreover, nanoparticles that are free to move in solution can be made to rotate extremely fast when illuminated by chiral light because the angular momentum carried by circularly polarized photons has to be conserved in the light-matter interaction. I will discuss several examples of such effects based on recent data, including fabrication and analysis of 3D chiral metallic and dielectric nanoparticles and metasurfaces made by colloidial lithography, hot-electron and cathodoluminescence generation in chiral nanostructures, and optical rotation experiments on gold nanorods interacting with molecules.
5:00 PM - *ED14.8.06
Photo-Thermal Control of Gold Nanoparticle Loaded Microgel Systems
Dmitry Chigrin 1 2
1 , RWTH Aachen University, Aachen Germany, 2 , DWI–Leibniz Institute for Interactive Materials, Aachen Germany
Show AbstractMicrogels are cross-linked polymeric chains with dimensions ranging from several hundreds of nano- to a few tens of micro-meters. Microgels are highly sensitive to the environmental changes and can change their swelling behaviour (shape and volume) in response to external stimuli such as temperature, pressure, pH, and ionic strength. This ability has attracted a lot of attention due to potential applications of microgels as micro-sensors, micro-actuators, micro-valves and drug delivery devices. In particular temperature-responsive microgels can exhibit extremely large deformation due to the volume transition in response to changes in temperature. Combining photo-thermal materials, e.g. plasmonic nano-particles, with microgels opens a unique opportunity to design micro-dynamical systems (micro-swimmers, micro-actuators, micro-machines) which can be controlled all-optically. In this presentation we discuss physical modelling of gold nano-particle loaded microgels. A description of photo-thermally activated microgels involves self-consistent coupling of diffusion, elasticity, heat transfer and electrodynamic models. Using simple examples we discuss how swelling/deswelling dynamics of microgel can be controled and guided using light.
5:30 PM - ED14.8.07
Near-Infrared Plasmon - Plasmon and Plasmon - Vibration Coupling with Faceted Metal Oxide Nanocrystals
Ankit Agrawal 1 , Ajay Singh 1 , Sadegh Yazdi 2 , Emilie Ringe 2 , Delia Milliron 1
1 , The University of Texas at Austin, Austin, Texas, United States, 2 , Rice University, Houston, Texas, United States
Show AbstractAbility to enhance and localize electric field at an interface on the nanoscale, well below diffraction limit makes plasmonic nanocrystal promising optical element for the wide variety of applications. Due to high electron density in Au and Ag, they have plasmon in the visible region. Metal oxide nanocrystals (NCs) such as Sn:In2O3, In:CdO, or Al:ZnO etc. are degenerately doped and wide band gap semiconductor. Due to highly variable carrier concentration in such material, it enables plasmon frequency ( over the entire infrared region. Our previous studies have shown that in metal oxide can be tuned by controlling doping level (oxygen vacancy or extrinsic doping) or by electrochemically charging the NC film1. In both the cases, due to its wide band gap, it largely retains its visible transparency. The development of metal oxide plasmonic platform for molecular sensing could lead to easy to make and electrically tunable SEIRA substrates.
In this work, the near field enhancement and plasmonic coupling of doped indium oxide NCs are revealed. Dopant drove NC shape evolution and thereby correlated plasmon property of colloidally synthesized octahedron and cuboctahedron Sn:In2O3 (ITO) and cubic fluorine (F) and tin (Sn) codoped In2O3 (FITO) was studied. Incorporation of F dopant into Sn:In2O3 was found to drive the shape from octahedron to cubic as well as decrease the ionic defect scattering. Furthermore, we demonstrated the size dependent plasmon property of FITO, mapping of the near field enhancement property of single cubic nanocrystals via EELS and both far field and near field plasmon property via COMSOL electromagnetic simulations. NC plasmon – plasmon coupling in the chain of nanocrystals, as well as 2D structure, is mapped via EELS, and it shows the induction of hot spot in metal oxide nanocrystal. Simulation of the periodic structure has further shown strong NC size dependence. Furthermore, we have experimentally and computationally shown how C-H molecular bonds (2800-3200 cm-1) couples to the periodic film of FITO NC. Effect of plasmon frequency about molecular bond frequency and size of nanocrystals was found to change the Fano line shape of molecular vibration due to changing coupling mechanism.
References:
(1) Garcia, G.; Buonsanti, R.; Llordes, A.; Runnerstrom, E. L.; Bergerud, A.; Milliron, D. J. Near-Infrared Spectrally Selective Plasmonic Electrochromic Thin Films. Adv. Opt. Mater. 2013, 1 (3), 215–220.
5:45 PM - ED14.8.08
Adjusting the Localized Surface Plasmon Resonance in Degenerately Doped Colloidal Copper Chalcogenide Nanocrystals via Various Chemical Modifications
Dirk Dorfs 1
1 Institut für Physikalische Chemie und Elektrochemie, Leibniz Universität Hannover, Hannover Germany
Show AbstractSo called localized surface plasmons resonances (LSPRs) are a well-known phenomenon in metal nanoparticles. They have attracted lots of research interest e.g. for near field enhancement applications or in sensing applications. In the recent past it was reported that LSPRs are indeed not limited to metallic nanoparticles but can also occur in degenerately doped semiconductor materials with sufficiently high charge carrier densities. Copper chalcogenides like Cu2-xSe and Cu1.1S are examples for such materials. They are capable of supporting LSPRs in the near infrared part of the spectrum with a LSPR peak position which is easily tunable by adapting the dopand degree (e.g. the amount of Cu vacancies in the case of Cu2-xSe).(1-2) The pure copper chalcogenides however are typically very oxygen sensitive and therefore have a limited applicability. This presentation will summarize the plasmonic properties of the mentioned copper chalcogenide nanoparticles and especially focus on various chemical approaches (partial ion exchange, metal growth, shell growth) to modify their plasmonic properties and to enhance their stability under ambient conditions.(3-6)
(1) Dorfs, D.; Hartling, T.; Miszta, K.; et al. J. Am. Chem. Soc. 2011, 133, 11175.
(2) Scotognella, F.; Della Valle, G.; Kandada, A. R. S.; Dorfs, D.; et al. Nano Lett. 2011, 11, 4711.
(3) Wolf, A.; Kodanek, T.; Dorfs, D.; Nanoscale 2015, 7, 19519-19527.
(4) Wolf, A.; Härtling, T., Hinrichs. D.; Dorfs, D.; ChemPhysChem 2016, 17, 717.
(5) Wolf, A.; Hinrichs, D.; Sann, J.; Miethe, J.F.; Bigall, N.C.; Dorfs, D.; J. Phys. Chem. C 2016, 120, 21925.
(6) Wolf, A.; Diestel, L.; Lübkemann, F.; Kodanek, T.; Mohamed, T.; Caro, J.; Dorfs, D.; Chem. Mater. 2016, just accepted, DOI: 10.1021/acs.chemmater.6b03425