学术报告--同步辐射高压非弹性散射- 探测电子、磁性、弹性和光子性能（美国Texas大学林俊孚博士）

同步辐射高压非弹性散射—探测电子、磁性、弹性和光子性能

Synchrotron Inelastic X-ray Scattering at High Pressures:

Probing Electronic, Magnetic, Elastic, and Phonon Properties

Jung-Fu “Afu” Lin (林俊孚)

Department of Geological Sciences, Jackson School of Geosciences

The University of Texas at Austin

报告时间：2011年11月9日上午10:00

报告地点：北京同步辐射装置12号厅会议室

报告摘要： 

The advent of the synchrotron-based inelastic X-ray scattering spectroscopies offers a plethora of research opportunities to investigate material properties at extreme pressure-temperature environments. Here I will present recent technical developments and scientific outcomes in inelastic X-ray scattering techniques, including high-energy resolution inelastic X-ray scattering (HERIX), nuclear resonant inelastic X-ray scattering (NRIXS), synchrotron Mössbauer spectroscopy (SMS), X-ray Raman spectroscopy (XRS), X-ray emission spectroscopy (XES), and resonant XES (RXES). These techniques have been coupled with laser-heated or cryogenically-cooled diamond anvil cells and synchrotron X-ray diffraction techniques to unleash new insights into phonon dispersion curves, phonon density of states, electronic structures (e.g., spin and valence states), magnetism, elasticity, bonding characters, among many others. These techniques each carry unique, complementary capabilities that probe different momentum and energy transfers caused by interactions between the incident light and the lattice. Energy (or frequency) and momentum (or wavevector) transfers between incoming and scattered X-ray sources categorize the techniques into ranges that provide probing access to many properties in materials. In particular, the tightly focused X-ray beams with extremely high fluxes now make it possible to study micro-sized materials in extreme pressure-temperature environments. These studies afford important clues about, for example, the local atomic arrangement, the strength of the chemical bonds related to forces acting on a particular atom of interest, and the effect of ligands on the overall lattice dynamics. In particular, I will address the use of the HERIX and NRIXS techniques to measure acoustic phonon dispersion curves for derivations of the full elastic constants of iron alloys at high pressures. These techniques probe energy transfers in the order of hundred meV and momentum transfers of approximately 0.1-10 nm-1 that arise from the phonon dispersions in the lattice. Future challenges and research opportunities in studying materials properties using these techniques under extreme environments will also be presented so as to stimulate CAS scientists to explore this new frontier collaboratively.