Sound Velocities at High Pressure: An Application of Laser Induced Phonon Spectroscopy

高压声速：激光诱导声子光谱的应用

• 批准号: 8804897
• 负责人: J Brown
• 金额: $ 28.07万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-01-15 至 1992-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8804897&HistoricalAwards=false
• 关键词: Sound; Velocities; Pressure; Application; Laser

The PI will assemble a laboratory at the University of Washington for the purpose of measuring sound velocities of candidate mantle minerals at high pressure and temperature. On the basis of successful preliminary experiments, he has demonstrated that it is feasible to make such measurements on small (100 um) samples in a diamond anvil high pressure cell. Impulsive stimulated scattering (ISS) in the form of laser induced phonon spectroscopy provides a robust technique to investigate the elastic properties of crystals at high pressure. Coherent phonons, generated by a pair of overlapping laser pulses, temporally and spatially modulate the index of refraction of sample. A probe laser pulse can be strongly diffracted by the resultant time-dependent grating. Signals are orders of magnitude greater than with any other technique. This technique also side-steps the uncertain index-of-refraction problem often associated with Brillouin scattering experiments. The determination, under mantle conditions, of pressure and temperature derivatives of elastic constants for candidate mantle constituents is one of the important current problems in mineral physics.

PI将在华盛顿大学组建一个实验室，用于测量候选地幔矿物在高压和高温下的声速。在成功的初步实验的基础上，他证明了在金刚石砧座高压室中对小样品(100um)进行这种测量是可行的。激光诱导声子谱形式的脉冲受激散射(ISS)为研究高压下晶体的弹性性质提供了一种可靠的技术。相干声子由一对重叠的激光脉冲产生，在时间和空间上调制样品的折射率。由此产生的含时光栅可以使探测激光脉冲发生强烈的衍射。信号比任何其他技术都要大几个数量级。这项技术还避开了通常与布里渊散射实验相关的不确定折射率问题。在地幔条件下，确定候选地幔组分的压力和温度导数弹性常数是当前矿物物理的重要问题之一。