School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, GPO Box 2434, Brisbane Queensland 4001, Australia.
Spectrochim Acta A Mol Biomol Spectrosc. 2012 Sep;95:263-9. doi: 10.1016/j.saa.2012.04.021. Epub 2012 Apr 23.
The bright blue minerals cavansite and pentagonite, a calcium vanadium silicate Ca(V(4+)O)Si(4)O(10)·4H(2)O, have been studied by UV-Visible, Raman and infrared spectroscopy. Cavansite shows an open porous structure with very small micron sized holes. Strong UV-Visible absorption bands are observed at around 403, 614 and 789 nm for cavansite and pentagonite. The Raman spectrum of cavansite is dominated by an intense band at 981cm(-1) and pentagonite by a band at 971 cm(-1) attributed to the stretching vibrations of (SiO(3))(n) units. Cavansite is characterised by two intense bands at 574 and 672 cm(-1) whereas pentagonite by a single band at 651 cm(-1). The Raman spectrum of cavansite in the hydroxyl stretching region shows bands at 3504, 3546, 3577, 3604 and 3654 cm(-1) whereas pentagonite is a single band at 3532 cm(-1). These bands are attributed to water coordinated to calcium and vanadium. XPS studies show that bond energy of oxygen in oxides is 530eV, and in hydroxides ∼531.5 eV and for water ∼533.5 eV. XPS studies show a strong peak at 531.5eV for cavansite, indicating some OH units in the structure of cavansite.
亮蓝色的矿物钙菱沸石和五角沸石，是一种钙钒硅酸盐 Ca(V(4+)O)Si(4)O(10)·4H(2)O，已经通过紫外-可见、拉曼和红外光谱进行了研究。钙菱沸石呈现出具有非常小的微米级孔的开放多孔结构。钙菱沸石和五角沸石在大约 403、614 和 789nm 处观察到强的紫外-可见吸收带。钙菱沸石的拉曼光谱主要由 981cm(-1)处的强带和五角沸石的 971cm(-1)处的带主导，归因于(SiO(3))(n)单元的伸缩振动。钙菱沸石的特征是在 574 和 672cm(-1)处有两个强带，而五角沸石在 651cm(-1)处只有一个带。钙菱沸石在羟基伸缩区域的拉曼光谱显示出在 3504、3546、3577、3604 和 3654cm(-1)处的带，而五角沸石在 3532cm(-1)处只有一个带。这些带归因于与钙和钒配位的水。XPS 研究表明，氧化物中氧的键能为 530eV，而在氢氧化物中约为 531.5eV，对于水约为 533.5eV。XPS 研究表明钙菱沸石在 531.5eV 处有一个很强的峰，表明钙菱沸石结构中有一些 OH 单元。
