10/10/17 -9:45 AM to 11:00 AM
Crawford Memorial Lectureship: Professor Keith A. Nelson
Bryce L. Crawford Memorial Lecture
“What would you measure in the terahertz range of the spectrum? A lot, it turns out: THz EPR, THz-induced charge transfer and chemical reactions, and 2D THz spectroscopy.”
With short-duration terahertz-frequency light pulses now readily available, new types of spectroscopy have become possible. Using simple commercial light sources and spectrometers, THz EPR measurements that reveal zero-field splittings of high-spin transition metal complexes are straightforward. The splittings are highly sensitive to molecular geometric and electronic structure. With strong THz fields, a wide range of novel possibilities emerges based on THz-induced nonlinear responses of electrons, lattice and low-frequency molecular vibrations, molecular rotations, and spins. The nature of THz strong-field interactions with these degrees of freedom and some of the dramatic responses that can be induced, including colossal Stark shifts, charge transfer and electroluminescence, chemical reactions, and phase transitions, will be illustrated. The dynamical responses have been probed with light from THz to x-ray spectral ranges. Coherent 2D THz spectroscopy including 2D EPR and 2D rotational spectroscopies will be discussed.
Professor Keith Nelson received his doctorate in physical chemistry from Stanford University in 1981, and after a post-doctoral stint at University of California, Los Angeles, he joined the faculty at the Massachusetts Institute of Technology in 1982.
He has worked on discovery of new light-matter interactions and their exploitation for spectroscopy and control of coherent acoustic waves, lattice and molecular vibrations, excitons, spins, and their admixtures with light. Professor Nelson has developed novel methods for study of solid-state chemical reactions, crystals near phase transitions, glass-forming liquids, electronic excited-state dynamics, thermal transport, and matter far from equilibrium. He has pioneered tabletop generation of strong terahertz-frequency fields and nonlinear terahertz spectroscopy.
Bryce L. Crawford Jr.
Bryce L. Crawford Jr. was a renowned Department of Chemistry professor and scientist. He died in September 2011, at the age of 96. He joined the department in 1940, and became a full professor of physical chemistry in 1946. He was chair of the department from 1955 to 1960, and was dean of the graduate school from 1960 to 1972. He retired in 1985. He loved studying molecular vibrations and force constants, and the experimental side of molecular spectroscopy and molecular structure. During World War II, Crawford worked in research on rocket propellants, making significant contributions to rocketry, and the development of solid propellants for the much larger rockets that evolved after the war. Crawford received many honors during his career, including the prestigious American Chemical Society Priestley Medal; and being named a Fellow of the Society for Applied Spectroscopy, a Guggenheim Fellow at the California Institute of Technology, and a Fulbright Fellow at Oxford University. He held the distinction of membership in three honorary science academies, and was actively involved in many professional associations.