光电化学系列讲座（十四） 2009-3-11

中国可再生能源学会、光化学委员会光电化学系列讲座（十四）：

报告人：Prof. H. Peter Lu
Department of Chemistry and the Center for Photochemical Sciences, Bowling Green State University, U.S.A.

Prof. H. Peter Lu got his B.S. and M.S. from Peking University in 1982 and 1984.He got his M. Sci and Ph. D. from Columbia University in 1987 and 1991. From 1991 to 1995, he was a research associate in epartment of Chemistry, Northwestern University. From 1995 to 2006, he worked in Pacific Northwestern National Laboratory as a postdoctoral fellow, a senior research scientist and chief scientist, respectively. Since 2006, he has been an Ohio Eminent Scholar and Professor of Chemistry in Bowling Green State University. His research interest focuses on single-molecule spectroscopy studies of molecular kinetics and dynamics in condensed phase and at interfaces. He is the author or co- author of more than 50 scientific publications including Nature, Phys. Rev. Lett., J. Am. Chem. Soc., Appl. Phys. Lett. and so on.

报告题目：Probing Single-Molecule Interfacial Electron Transfer Dynamics

内容提要：
Interfacial electron transfer dynamics is important for solar energy conversion, environmental and catalytic reactions. Extensive ensemble-averaged studies have indicated inhomogeneous and complex dynamics of interfacial ET reactions. To characterize the inhomogeneous dynamics and the complex mechanism, we have applied single-molecule spectroscopy and correlated AFM/STM imaging to study the Interfacial ET dynamics of dye molecules adsorbed at the surface of TiO2 nanoparticles. The interfacial ET activity of individual dye molecules showed fluctuations and intermittency at time scale of milliseconds to seconds. The fluctuation dynamics were found to be inhomogeneous from molecule to molecule and from time to time, showing significant static and dynamic disorders in the dynamics. The observed reaction rate fluctuations (from femtoseconds to seconds) are beyond the conventional kinetic scope and can be characterized by Levy statistics. Furthermore, we have applied site-specific AFM-Raman spectroscopy on analyzing ET associated mode-specific vibrational reorganization energy barriers. Our experiments revealed site-to-site variations in the vibrational reorganization energy barriers in the interfacial ET systems. The intermittent ET dynamics is most likely common for the interfacial chemical reactions that strongly regulated by the molecular interaction between adsorbed molecules and substrate surfaces. The spontaneous thermal fluctuations of the local environment and the molecular interactions occur at a wide time-scale at room temperature, resulting in the interfacial ET reaction-rate fluctuation and inhomogeneous dynamics. Our single-molecule spectroscopy analysis provides novel and detailed information about the inhomogeneity of the interfacial electron transfer, which is consistent but not obtainable from the conventional ensemble-averaged experiments.