Washington State University

报告人简介：
Professor Choong-Shik Yoo is a world leading scientist on high pressure research. Professor Yoo received his Ph.D. in Physical Chemistry in 1986 from UCLA. He is currently Professor of Department of Chemistry and Institute for Shock Physics at Washington State University. His research is on fundamental materials problems under extreme pressure/temperature conditions. His research utilizes static and dynamic high-pressure capabilities coupled with the state-of-the-art laser spectroscopic methods and x-ray diffraction and spectroscopy at the national synchrotron and neutron facilities. He earned twice DOE awards for excellence research. He served as a vice President for the International Association for the Advancement of High Pressure Science and Technology (AIRAPT) and co-chaired a APS-SCCM/AIRAPT joint conference in Seattle, 2013. He delivered more than 100 plenary/keynote/invited talks in international conferences. He published about 280 papers including in Science, Nature, PNAS, etc with high citations.

报告摘要:
Hydrogen (H2) and helium (He) are two most fundamental solids abundant in the Universe. Compression behaviors of H2 and He are critical to understand many body effects of these quantum solids; develop new condensed matter theories; and get insights into the internal structure of the Giant planets. In contrast to a rapid progress in understanding the phase diagram of H2 at high pressures, a little is known about the phase behaviors of the mixtures of these most fundamental quantum solids, H2 and He. In this lecture, I will describe our recent studies on the binary phase diagram of H2 and He, underscoring the formation of metastable H2-rich crystallite in He-rich fluid mixtures and the structural phase transition in He lattice at ~52 GPa. The Raman data also indicates a significant level of mixing between H2 and He, resulting in strong chemical association of the interstitial-filled guest molecules (H2 or He) with the host lattice (hcp-He or H2), as well as unexpected chemistry in the most inert solid He to form hydrides and nitrides.

邀 请 人：靳常青（电话：8264 9163）
联 系 人：李园园（电话：8264 9364）