Raman Spectroscopy Under Simultaneous High Pressure - High Temperature in a Laser Heated Diamond Cell: Thermal Pressure, Heat Capacity, Entropy, Thermal Expansivity, and Anharmonic

拟议的工作包括在各种压力和温度条件下测量矿物的振动模式，这允许通过统计方法或振动建模对这种矿物进行热力学表征。 到目前为止，使用振动模型获得的有用信息包括热容，熵，热膨胀系数和声速的压力导数。 一个重要的结果还没有得到充分利用：在给定的P和T的热压力可以通过使用内部能量的振动模型，从PTH = gEvib/V导出。因此，在同时的高压和温度下的振动研究允许计算状态方程，这将支持矿物的热状态方程的许多X射线衍射研究。 振动建模也将有助于提供一种外推的手段超出所有热力学性质的测量范围。将探讨磁性和电子对含铁矿物（或任何其他过渡金属）的热容和熵的贡献。拟议的实验室工作包括拉曼光谱在激光加热金刚石砧室的发展。 工作将集中在振动光谱和状态方程的关键地幔阶段之间的相关性，但也将包括其他关键的热弹性参数。 需要一个小型的，单单色系统，用于现场温度测量。 我们建议扩展目前的拉曼光谱的能力，在我们的实验室在华盛顿大学，允许同时高温和高压下使用二氧化碳激光加热的金刚石砧细胞。 一旦仪器就位，将研究其热状态方程已通过X射线衍射确定的矿物学上重要的矿物，包括MgSi钙钛矿和镁橄榄石及其高压多晶型物以及其他MgSiO 3相。 除了在同时的高压和高温下获得拉曼的一阶目标之外，金刚石砧室中的原位激光加热将提供其他有用的数据：适当的相边界将在原位确定并且任何不可淬灭的相可以被检测，根据拉曼光谱模式确定可能的结构或空间群。体积是许多其他性质在许多地球内部的温度、成分和动力学模型。 在所有深Earch条件下的V（P，T）以及压力下的热容和熵对于地球科学和物理学的许多分支的工作者来说是无价的，包括地球物理学，地球动力学，矿物学和岩石学以及凝聚态物理学。 PI接待了六名本科生研究人员，包括两名女性，参加实验室的研究。 目前的研究生是一名美国土著妇女，是少数获得博士学位的人之一。在任何领域。

The proposed work consists of the measurement of vibrational modes of minerals at various pressure and temperature conditions, which allows thermodynamic characterization of this mineral through statistical methods or vibrational modeling. Useful information obtained so far using vibrational modeling includes the pressure derivatives of heat capacities, entropies, thermal expansivities, and sound velocities. One important result has not yet been fully exploited: Thermal pressure at a given P and T may be derived using vibrational modeling of internal energy, from PTH = gEvib/V. Thus, vibrational studies at simultaneous high pressure and temperature allow computation of the equation of state, which will support the many x-ray diffraction studies of the thermal equation of state of minerals. Vibrational modeling will also help provide a means for extrapolation beyond the range of the measurements of all thermodynamic properties. Magnetic and electronic contributions to heat capacity and entropy for iron-bearing minerals (or any others with transition metals) will be explored. The proposed laboratory work consists of the development of Raman spectroscopy in the laser heated diamond anvil cell. The efforts will concentrate on the correlation between vibrational spectra and the equations of state of key mantle phases, but will also include the other key thermoelastic parameters. A small, single monochromator system for in situ measurements of temperature is requested. We propose to extend the current Raman spectroscopic capabilities in our laboratory at UW to allow simultaneous high temperatures and pressures using CO2 laser heating in the diamond anvil cell. Once the instrument is in place, geophysically important minerals whose thermal equations of states have been determined by x-ray diffraction will be studied, including MgSi perovskite and forsterite and its high pressure poly-morphs as well as the other MgSiO3 phases. In addition to the first-order goal of obtaining Raman at simultaneous high pressures and temperatures, in situ laser heating in the diamond anvil cell will provide other useful data: phase boundaries where appropriate will be determined in situ and any unquenchable phases can be detected, with probable structures or space groups identified based on Raman spectral patterns.Volume is the parameter against which many other properties are scaled in many temperature, compositional and dynamical models of the Earth's interior. V(P,T) at all deep Earch conditions as well as heat capacity and entropy at pressure will be invaluable to workers in many branches of geoscience and physics, including geophysics, geodynamics, mineralogy, and petrology as well as condensed matter physics. The PI has hosted six of undergraduate researchers, including two women, to participate in research in the laboratory. The PIs current graduate student is a Native American woman, one of the very few to obtain a Ph.D. in any field.