Jeremy Baumberg1
University of Cambridge1
Light can be confined through plasmonics to the nanoscale using coinage metals, particularly tightly within nm-wide dielectric gaps between metal facets. I will present recent advances in the nanoparticle-on-mirror concept [1] which creates robust and atomic-scale precision nanocavities that finally open up systematic exploration of many light-matter coupled phenomena. I will demonstrate how the size and shape of the nanoparticle facets play a key role, and can be controlled to modify in-/out-coupling of light. Enhanced structures can show hundred-fold increases in SERS emission (exceeding a million counts/mW/s) which enables high speed real-time interrogation of the dynamics of individual atoms and molecules in the nanocavities.<br/>I will show a variety of phenomena from single de/protonation events [2], single molecule catalytic chemistry, and electrochromic functionalities [3], to the ability to create low-cost uncooled detectors of mid-IR light through upconversion in such plasmonic nanocavities [4]. I will also show that these structures can be simply wired up for a variety of molecular electronics and photoconductive devices [5,6]. I will introduce how optical forces are hundred-fold enhanced in such nanocavities [7-9]. I will finally discuss the prospects for such nanoscale building blocks across a variety of fields.<br/><br/>[1] Extreme nanophotonics from ultrathin metallic gaps, Nature Materials <b>18</b>, 668 (2019); DOI: 10.1038/s41563-019-0290-y<br/>[2] Tracking interfacial single-molecule pH and binding dynamics..., Science Advances 7:eabg1790 (2021); DOI: 10.1126/sciadv.abg1790<br/>[3] Scalable electrochromic nano-pixels using plasmonics, Science Advances (2019); DOI: 10.1126/sciadv.aaw2205<br/>[4] Detecting mid-infrared light by molecular frequency upconversion in dual-wavelength nanoantennas, Science (2021); DOI: 10.1126/science.abk2593<br/>[5] Optical probes of molecules as nano-mechanical switches, Nature Comm <b>11</b>:5905 (2020); DOI: 10.1038/s41467-020-19703-y<br/>[6] Quantum Tunneling Induced Optical Rectification and Plasmon-Enhanced Photocurrent in Nanocavity Molecular Junctions, ACS Nano (2021); DOI: 10.1021/acsnano.1c04100<br/>[7] Optical suppression of energy barriers in single molecule-metal binding, Science Advances 8: eabp9285 (2022); DOI: 10.1126/sciadv.abp9285<br/>[8] Picocavities: a primer, Nano Letters <b>22</b>, 5859 (2022); DOI: 10.1021/acs.nanolett.2c01695<br/>[9] Single-molecule optomechanics in picocavities, Science <b>354</b>, 726 (2016); DOI: 10.1126/science.aah5243