Spectroscopic Determination of the Thermodynamic Properties of Minerals as a Function of Pressure

拟议的研究包括在压力下使用振动光谱，以便(1)提供热容、熵和热Gruneisen参数的数据，用于量热法无法达到的压力和温度区域；(2)表征矿物在压力下的结构变化。此外，将获得完整的单晶红外光谱(1)以取代目前可用的不准确和不完整的粉末数据，(2)正确解释高压测量结果。提出的理论处理方法是：(1)建立一个将剪切模量及其压力导数与压力下的振动数据联系起来的公式，(2)提供一个可以在测量范围之外外推的热膨胀率的经验公式。这些数据与这些理论工作的结合将促进对矿物热力学和弹性性质的认识。最终目的是通过与地震模型的比较推断出地球内部的成分和热特性。

The proposed research involves use of vibrational spectroscopy at pressure in order to (1) provide data on heat capacity, entropy, and the thermal Gruneisen parameter for pressure and temperature regions inaccessible to calorimetry and (2) characterize structural changes of minerals with pressure. In addition, complete single-crystal IR spectra will be acquired (1) to replace the inaccurate and incomplete powder data that is currently available, and (2) to correctly interpet the high- pressure measurements. Theoretical treatments proposed are to (1) develop a formulation relating the shear modulus and its pressure derivatives to vibrational data at pressure, and (2) provide an empirical formulation for thermal expansivity that can be extrapolated beyond the range of measurements. Combination of the data with such theoretical work will advance knowledge of the thermodynamic and elastic properties of minerals. The ultimate goal is deduction of the composition and thermal character of the earth's interior through comparision to seismic models.