We are excited to announce that our effort that started 2 years ago as the California Interfacial Science Initiative has received new funding through the UC MRPI program. With this $1.1M in direct funding we will extend the capacity and become the California Interfacial Science Institute. In the next 3 years we will continue our work on studying chemically-relevant interfaces by combination of theory and experiment and we now include additional leading researchers from UCLA and UC Santa Barbara. We also will establish a novel undergraduate research fellowship for conducting summer research in CISI affiliated laboratories.
Additional details can be found in the College of Chemistry press release here:
We are excited to see our latest paper on “Coherent Phonons in Antimony: An Undergraduate Physical Chemistry Solid-State Ultrafast Laser Spectroscopy Experiment” published in the ACS Journal of Chemical Education. This paper in chemical education discusses in deep detail an ultrafast spectroscopy experiment that we developed for our undergraduate teaching laboratory at Berkeley. In the experiment, the students measure coherent phonons in antimony using the output of a femtosecond laser oscillator which they also characterize in the time domain. This lab experiment that is usually done by juniors and seniors in the Chemistry curriculum has since its inauguration become one of the favorite experiments that students in this course do. We hope it will spark excitement for research using ultrafast methods in their future careers.
This work was done in collaboration with Steve Leone and Anne Baranger.
Our open access paper is now published in the Journal of Chemical Education:
Topological defects play a key role in nonequilibrium phase transitions, ranging from birth of the early universe to quantum critical behavior of ultracold atoms. In solids, transient defects are known to generate a variety of hidden orders not accessible in equilibrium, but how defects are formed at the nanometer lengthscale and femtosecond timescale remains unknown. In this work, we discovered the sub-picosecond formation of 1D topological defects in a two-dimensional charge density wave using ultrafast electron diffraction. We discovered a dual-stage growth of 1D domain walls which takes place within 1 ps which is mediated by nonthermal lattice vibrations. This work constitutes the first visualization of topological defect formation process in the femtosecond timescale. Our work provides a framework for ultrafast engineering of topological defects based on selective excitation of collective modes, opening new avenues for dynamical control of nonequilibrium phases in correlated materials.
This work was done in collaboration with researchers from Shanghai Jiao Tong University, Brookhaven National Laboratory, ShanghaiTech University, University of Amsterdam and UCLA.
Pre-print available here: