TIME-RESOLVED DIFFUSE SCATTERING FROM LASER-EXCITED SEMICONDUCTORS

激光激发半导体的时间分辨漫散射

• 批准号: 7956835
• 负责人: DAVID REIS
• 金额: $ 8.02万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2010-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7956835
• 关键词: Communities; Computer Retrieval of Information on Scientific Projects Database; Diffuse; Equilibrium; Funding; Grant; Institution; Lasers; Mechanics; Optics; Phase; Phase Transition; Physiologic pulse; Population; Process; Property; Research; Research Personnel; Resources; Roentgen Rays; Semiconductors; Solid; Source; Techniques; Testing; Time; United States National Institutes of Health; Visible Radiation; interest; irradiation; novel; research study; structural biology; time use; tool

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Intense, ultrashort laser pulses provide us with a way to access non-equilibrium states in solids by excitation of coherent phonons. Because the phonons in the material determine the mechanical and thermal properties, it is of great interest to develop tools to study the dynamics of the nonequilibrium phonon population induced by the laser. In addition, laser excitation can be used to access other nonequilibrium phases of matter through, for example, novel phase transitions involving lattice instabilities at high wavevector. Because of the long wavelength of visible radiation, only a small volume of the Brillouin zone is accessed in optical experiments. There is currently no experimental technique that can provide time-resolved information of the complete phonon branches of the solid. Time-resolved x-ray diffuse scattering (TRXDS) has the potential to be the ultimate tool to study these nonequilibrium processes throughout the Brillouin-zone of the crystal. We propose to use time-resolved diffuse X-ray scattering to study the lattice instability of Si and GaP induced by intense laser irradiation. The proposed experiment serves as a test of the feasibility of time-resolved x-ray diffuse scattering at APS and could potentially benefit a large part of the community with the advent of novel sources as the LCLS.

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 强烈的超短激光脉冲为我们提供了一种通过激发相干声子进入固体非平衡态的方法。由于材料中的声子决定了材料的力学和热学性质，因此开发研究激光诱导的非平衡声子布居动力学的工具具有很大的意义。此外，激光激发可用于通过例如涉及高波矢处的晶格不稳定性的新相变来访问物质的其他非平衡相。 由于可见光辐射的波长较长，在光学实验中只能获得很小体积的布里渊区。目前还没有实验技术，可以提供完整的声子分支的固体的时间分辨信息。时间分辨X射线漫散射（TRXDS）有可能成为研究这些非平衡过程的最终工具，在整个布里渊区的晶体。我们建议使用时间分辨的X射线散射来研究强激光辐照引起的Si和GaP的晶格不稳定性。拟议的实验作为时间分辨x射线漫散射在APS的可行性测试，并可能受益于社区的大部分新来源的LCLS的出现。