Zoom Link - https://columbiauniversity.zoom.us/s/94880211361
Coherent Spectroscopy and Microscopy: Theory and Applications
Presented by Prof. Minhaeng Cho, Korea University, Seoul
How atoms and electrons in a molecule move during a chemical reaction and how rapidly energy is transferred to or from the surroundings can be studied with flashes of laser light. Over the past two decades, extensive and prolonged efforts to develop various coherent multidimensional spectroscopic techniques have been made, which are capable of both femtosecond time resolution and wide dynamic range measurements for studying correlated electron dynamics in functional materials and biological systems. In this lecture, the fundamental principles of nonlinear vibrational/electronic spectroscopy will be discussed first. I will briefly introduce our new time-resolved spectroscopic techniques utilizing multiple mode-locked lasers, which are markedly different from the conventional approaches using a single amplified laser. In parallel with the development of ultrafast laser spectroscopic techniques, a variety of vibrational (IR or Raman) probes have been developed and used to extract information on local electrostatic and H-bonding environment around those probes. The basic theory of vibrational solvatochromism based on the physical approximation, e.g., intermolecular interaction, or the machine learning approach will be discussed. Then, I will present a few representative applications of coherent spectroscopy and microscopy in IR or visible frequency domains: (i) solvation structure and dynamics in lithium battery electrolytes, (ii) ultrafast (<100 fs) electron dynamics and relaxation (> ps) in metallic nanoparticles and IR-absorbing intraband quantum dots, (iii) 2D electronic spectroscopic study of light-harvesting complex, (iv) interference scattering microscopy of cargo transports in live cells, and (v) adaptive optical coherent Raman scattering microscopy of deep tissue samples and mouse brain. Finally, a few concluding remarks with perspectives will be given.
Minhaeng Cho is the director of the IBS Center for Molecular Spectroscopy and Dynamics, established in Dec. 2014 and Professor of Chemistry at Korea University, Seoul, Korea, since 1996. He grew up in Seoul, where he attended the public schools. He received his B.S. and M.S. from Seoul National University in 1987 and 1989, respectively, before studying in the U.S. A. where he received his Ph.D. in 1993 from the University of Chicago. He returned to Korea in 1996 as an Assistant Professor at the Korea University after a two-year post-doctoral research experience at MIT, Cambridge, USA. He became a full Professor at the Korea University in 2003 before his directorship with IBS in 2014. IBS Center for Molecular Spectroscopy and Dynamics (CMSD), located in the Seoul campus of Korea University, emphasizes developments of novel time- and space-resolved spectroscopy techniques and their applications to chemically reactive and biologically important systems. He is a member of the Korean Academy of Science and Technology (KAST) and received numerous awards given by the American Chemical Society, National Science Foundation in Korea, KAST, Kyung-Am Science Foundation, and National Academy of Science in Korea.