石榴子石族矿物的拉曼光谱

REMAN SPECTRA OF GARNET-GROUP MINERALS

本文研究了石榴子石族各端员矿物(Fe-Al系列和Ca-Fe系列)的拉曼光谱。它们的拉曼光谱可归因于其中SiO_4的内模式、平移与旋转模式,以及X位置中二价阳离子的平移。对于Fe-Al系列矿物,其SiO_4的伸缩和旋转A_(lg)模式比Ca-Fe系列的有更大的拉曼位移,其原因在于结构的X多面体与SiO_4以共两条边相联。而Fe-Al系列矿物的X阳离子不同,从而使SiO_4产生不同程度的畸变。Fe-Al系列矿物的拉曼位移主要归因于X阳离子,而Ca-Fe系列矿物的拉曼位移则归因于Y阳离子的变化。

The Raman spectra of the natural end members of the garnet-group minerals, which include pyrope, almandine and spessarite of Fe-Al garnet series and grossularite, andradite and uvarovite of Ca-Fe garnet series, have been studied. Measured Raman spectra of these miner als are assigned to the internal modes, translational and rotatory modes of SiO_4 tetrahedra, as well as the translational motion of bivalent cation in the X site reasonably and qualitatively. The stetch and rotatory A_(1g) modes for the Fe-Al garnet series show obvious Raman shifts compared to those for the Ca-Fe garnet series, owing to the cations residing in the X site conncctcd with SiO_4 tetrahedra by sharing the two edges. The Raman shifts of all members within each series are mainly attributed to the features of cations in the X site for the Fe-Al garnet series and in the Y site for the Ca-Fe garnet series.