NMR in a Diamond Anvil Cell, Ruby Fluorescence, and the Ultra-high Pressure Scale

金刚石砧池中的 NMR、红宝石荧光和超高压刻度

• 批准号: 9971326
• 负责人: Isaac Silvera
• 金额: $ 35.98万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-05-01 至 2004-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9971326&HistoricalAwards=false
• 关键词: NMR; Diamond; Anvil; Cell; Ruby

9971326SilveraThis project has three thrusts in high pressure diamond anvil cell (DAC) physics: NMR; extension of the ruby pressure scale and the physics of ruby. A promising new geometry for NMR in a DAC has already extended the pressure range for this technique by more than a factor of 2 to a few hundred kilobars. The technique will be developed to extend to megabar pressures. Ortho-para conversion, important for the understanding of the properties of high pressure hydrogen will be studied directly by NMR to these high pressures. High pressure phases involve orientational ordering. Phase lines can be observed by the collapse of the Pake doublet in hydrogen to a singlet in going from the ordered to disordered phase. Theoretical calculations of metallization of hydrogen predict that the molecular bond shrinks then grows with increasing pressure. The bond length can be studied from the splitting of the Pake doublet. In a DAC the ruby fluorescence spectrum is the most important means of determining pressure. Currently, the quasi-hydrostatic scale is only calibrated to 80 GPa; we shall extend this to the multi-megabar range at a synchrotron, doing simultaneous measurements of the ruby spectrum and the equation of state of known pressure markers under the same pressure. We shall also study the solid phases of ruby as predicted phase changes have received little attention in this region and can also impact on the ruby pressure scale.%%%High pressure research extending into the megabar pressure range is a rapidly growing field of physics. In this program both graduate and undergraduate students are trained in methods of generating high pressure in Diamond Anvil Cells (DACs) on a table-top. Methods of nuclear magnetic resonance will be extended to megabar pressures, studying samples of hydrogen and its isotopes. Ruby will be studied in the megabar pressure range at a synchrotron radiation source to understand its structure, also producing an important new calibration of pressure in the megabar range.***

9971326 Silvera该项目在高压金刚石对顶砧（DAC）物理学方面有三个突破：NMR;红宝石压力范围的扩展和红宝石物理学。DAC中NMR的一种有前途的新几何结构已经将这种技术的压力范围扩展了2倍以上，达到几百个微帕。 这项技术将发展到兆巴压力。邻-对位转化对于理解高压氢的性质是重要的，将直接通过这些高压的NMR来研究。高压相涉及取向有序。 相线可以通过从有序相到无序相的过程中氢气中的Pake双峰坍缩成单线态来观察。 氢金属化的理论计算预测，分子键收缩，然后随着压力的增加而增长。 键长可以从Pake二重态的分裂来研究。 在DAC中，红宝石荧光光谱是确定压力的最重要手段。 目前，准流体静力学刻度仅校准到80 GPa;我们将在同步加速器上将其扩展到数兆巴范围，同时测量红宝石光谱和相同压力下已知压力标记的状态方程。 我们还将研究红宝石的固相，因为预测的相变在这一地区很少受到关注，而且也会影响红宝石的压力范围。%延伸到兆巴压力范围的高压研究是一个快速发展的物理学领域。在这个项目中，研究生和本科生都接受了在桌面上的金刚石砧室（DAC）中产生高压的方法的培训。核磁共振的方法将扩展到兆巴压力，研究氢及其同位素的样品。红宝石将在同步辐射源的兆巴压力范围内进行研究，以了解其结构，同时也在兆巴范围内产生重要的新压力校准。