Molecular electron transfer, as treated by the Marcus theory, strongly depends on nuclear motion as a way to achieve critical configurations in which charge rearrangement is possible. The electron tunneling process itself is assumed to occur in a static nuclear environment. In the application of the Landauer theory to conduction in molecular junctions, the electron transmission process is assumed to be elastic and nuclear motion is usually disregarded. This talk will focus several aspects of this issue. First, timescale criteria for disregarding or including nuclear motion in analyzing electron transmission through molecules and molecular layers will be presented. Second, the effect of nuclear motion on the overall transmission probability will be demonstrated for electron tunneling through water layers. Third, the effect of thermal relaxation and dephasing on the transition from tunneling to activated hopping as the dominant transmission mechanism will be considered. Finally, a framework for estimating heating and expected temperature rise in current carrying molecular junctions will be described. The latter issue requires consideration also of the heat conduction properties of molecular wires.
Abraham Nitzan was born in Israel in 1944.He received his B.Sc. in chemistry in 1964, his M.Sc. in physical chemistry in 1966, both from the Hebrew University, and his Ph.D. in 1972 from Tel Aviv University. He had a postdoctoral Fullbright Fellowship at MIT, was a research associate at the University of Chicago, and taught at Northwestern University before joining the Faculty at Tel Aviv University. At TAU he has been a Professor of Chemistry since 1982 and also served as Chairman of the School of Chemistry in 1984-7, and Dean of the Faculty of Science in 1995-8. He is a fellow of the APS and of the AAAS. Nitzan's research is in the field of chemical dynamics and transport phenomena in condensed phases. Recent work has focused on solvation and transport of ions in simple and complex solvents and in electron solvation and transport molecular environment and interfaces.
EE 317, Purdue University, West Lafayette, IN