Characterization of high pressure and natural samples by Raman spectroscopy

在提案期间，我们购买并安装了微型拉曼光谱系统所需的设备，以及金刚石砧室中原位光谱所需的 II 型钻石。安装的拉曼微探针系统是专门为满足我们高压材料研究小组的需求以及地球和太阳系材料研究的需求而设计的。安装的系统实现了非常高的性能，光谱分辨率约为0.5 nm，光通量很高。该系统现在在我们的实验室中常规使用，用于识别高压实验中合成的相并研究天然矿物。在提案期间，我们使用微拉曼来识别许多合成和天然的硅酸盐和氧化物相，并建立了一个文件作为参考标准。我们还使用微米拉曼系统肯定地鉴定了科罗拉多高原榴辉岩捕虏体中SiO_2高压多晶型柯石英的存在，这是该地区榴辉岩的首次报道。我们已经使用该系统研究了向硅酸钠熔体中添加硫对熔体形态和聚合的影响，并且正在继续研究解聚硅酸盐系统中的熔体形态。我们的实验室还经常使用微型拉曼系统，利用红宝石荧光来测量金刚石砧室中的原位压力。我们将继续从事拉曼显微镜发挥重要作用的项目。

In the proposal period we purchased and installed the equipment needed for a micro-Raman spectroscopy system, as well as the Type II diamonds needed for in situ spectroscopy in the diamond anvil cell. The installed Raman microprobe system was designed specifically to meet the needs of our high-pressure materials research group, and for the investigation of Earth and solar system materials. The installed system has achieved a very high performance, with a spectral resolution of about 0.5 nm and high optical throughput. This system is now used routinely in our lab for identification of phases synthesized in high-pressure experiments and to investigate natural minerals. In the proposal period we have used micro-Raman to identify many synthetic and natural silicate and oxide phases and have built a file to use as reference standards. We have also used the micron-Raman system to positively identify the existence of a high-pressure polymorph of SiO_2, coesite, in eclogite xenoliths from the Colorado plateau, the first reported for eclogites of this region. We have used the system to investigate the effect on melt speciation and polymerization of adding sulfur to sodium silicate melts, and are continuing investigations into melt speciation in depolymerized silicate systems. The micro-Raman system is also used routinely in our lab to measure pressure in situ in the diamond anvil cell using Ruby fluorescence. We are continuing to be engaged in projects in which Raman microscopy plays an important role.