Nanyang Technological University, Singapore

报告摘要：

Zhi-Heng Loh is Associate Professor in the School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University (NTU), Singapore. He received his S.B. from M.I.T. and Ph.D. from University of California, Berkeley. After postdoctoral research at UC Berkeley, including a brief stint at the Max Planck Institute of Quantum Optics, he returned to Singapore in 2010 to start; his independent career at NTU. His primary research interest lies in the study of ultrafast ionization-induced phenomena in gases, liquid water, and aqueous solutions, probed using femtosecond X-ray to infrared spectroscopies.

报告人简介：

The ionization of liquid water serves as the principal trigger for a myriad of phenomena that are relevant to radiation chemistry and radiation biology. The earliest events that follow the ionization of water, however, remain relatively unknown. Of particular interest are the lifetime of the transient water radical cation (H2O·+) and the fate of the electron that is injected into the conduction band of water by ionization. Femtosecond soft X-ray free-electron laser probing at the oxygen K edge is employed to observe the ~50-fs primary proton transfer reaction of ionized liquid water. By employing few-cycle pulses in the visible to near-infrared (500 – 900 nm) and the short-wave infrared (0.9 – 1.7 mm), we have performed a comprehensive probe of the fate of the electron that is initially injected into the conduction band by ionization. Extension of these studies to biomolecules in aqueous solution reveal vibrational wave packet dynamics induced by photoionization or photodetachment. Analysis of the wave packet dynamics reveals the normal modes that drive structural reorganization upon electron ejection and lifetimes of transient radical cations. Our results shed light on the elementary ultrafast dynamics that accompany the interaction of ionizing radiation with molecules of biological relevance.

邀请人：董朔（8125 8547）

联系人：胡颖（8264 9361）