Dec 2, 2024
11:30am - 12:00pm
Sheraton, Third Floor, Fairfax A
Christian Tanner1,Vivian Wall2,Mumtaz Gababa2,Joshua Portner1,Ahhyun Jeong1,Matthew Hurley3,Nicholas Leonard3,Jonathan Raybin2,James Utterback2,Ahyoung Kim2,Andrei Fluerasu4,Yanwen Sun5,Johannes Moeller6,Alexey Zozulya6,Jo Wonhyuk6,Anders Madsen6,Dmitri Talapin1,Samuel Teitelbaum3,Naomi Ginsberg2
The University of Chicago1,University of California, Berkeley2,Arizona State University3,Brookhaven National Laboratory4,SLAC National Accelerator Laboratory5,European XFEL6
Christian Tanner1,Vivian Wall2,Mumtaz Gababa2,Joshua Portner1,Ahhyun Jeong1,Matthew Hurley3,Nicholas Leonard3,Jonathan Raybin2,James Utterback2,Ahyoung Kim2,Andrei Fluerasu4,Yanwen Sun5,Johannes Moeller6,Alexey Zozulya6,Jo Wonhyuk6,Anders Madsen6,Dmitri Talapin1,Samuel Teitelbaum3,Naomi Ginsberg2
The University of Chicago1,University of California, Berkeley2,Arizona State University3,Brookhaven National Laboratory4,SLAC National Accelerator Laboratory5,European XFEL6
The ability to understand and ultimately control the transformations and properties of various nanoscale systems, from proteins to synthetic nanomaterial assemblies, hinges on the ability to directly elucidate their dynamics on their characteristic length and time scales. Here, we use MHz X-ray photon correlation spectroscopy (XPCS) to directly elucidate the characteristic microsecond-dynamics of density fluctuations of semiconductor nanocrystals (NCs), not only in a colloidal dispersion but also in a liquid phase consisting of densely packed, yet mobile, NCs with no long-range order. By carefully disentangling X-ray induced effects, we find the wavevector-dependent fluctuation rates in the liquid phase are suppressed relative to those in the colloidal phase and to those in experiments and hydrodynamic theories of densely packed repulsive particles. We show that the suppressed rates are due to a substantial decrease in the self-diffusion of NCs in the liquid phase, which we attribute to explicit attractive interactions. Via comparison with simulations, we find that the extracted strength of the attractions explains the stability of the liquid phase, in contrast to the gelation observed via XPCS in many other charged colloidal systems. This work opens the door to elucidating fast, condensed phase dynamics in a variety of complex fluids and other nanoscale soft matter systems, such as densely packed proteins and non-equilibrium self-assembly processes.