Frost Ray L, Cejka Jirí, Weier Matt L, Martens Wayde
Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, G.P.O. Box 2434, Brisbane, Qld. 4001, Australia.
Spectrochim Acta A Mol Biomol Spectrosc. 2006 Feb;63(2):305-12. doi: 10.1016/j.saa.2005.05.015. Epub 2005 Jun 21.
Raman spectroscopy has been used to study the molecular structure of a series of selected uranyl silicate minerals including weeksite K2[(UO2)2(Si5O13)].H2O, soddyite [(UO2)2SiO4.2H2O] and haiweeite Ca(UO2)2(Si5O12(OH)23 with UO2(2+)/SiO2 molar ratio 2:1 or 2:5. Raman spectra clearly show well resolved bands in the 750-800 cm(-1) region and in the 950-1000 cm(-1) region assigned to the nu1 modes of the (UO2)2+ units and to the (SiO4)4- tetrahedra. Soddyite is characterized by Raman bands at 828.0, 808.6 and 801.8 cm(-1), 909.6 and 898.0 cm(-1), and 268.2, 257.8 and 246.9 cm(-1), attributed to the nu1, nu3, and nu2 (delta) (UO2)2+, respectively. Coincidences of the nu1 (UO2)2+ and the nu1 (SiO4)4- is expected. Bands at 1082.2, 1071.2, 1036.3, 995.1 and 966.3 cm(-1) are attributed to the nu3 (SiO4)4-. Sets of Raman bands in the 200-300 cm(-1) region are assigned to nu2 (delta) (UO2)2+ and UO ligand vibrations. Multiple bands indicate the non-equivalence of the UO bonds and the lifting of the degeneracy of nu2 (delta) (UO2)2+ vibrations. The (SiO4)4- tetrahedral are characterized by bands in the 470-550 cm(-1) and in the 390-420 cm(-1) region. These bands are attributed to the nu4 and nu2 (SiO4)4- bending modes. The minerals show characteristic OH stretching bands in the 2900-3500 and 3600-3700 cm(-1).
拉曼光谱已被用于研究一系列选定的硅酸铀酰矿物的分子结构，包括周铀矿K2[(UO2)2(Si5O13)].H2O、硅钙铀矿[(UO2)2SiO4.2H2O]和海威矿Ca(UO2)2(Si5O12(OH)23，其UO2(2+)/SiO2摩尔比为2:1或2:5。拉曼光谱清楚地显示在750 - 800 cm(-1)区域和950 - 1000 cm(-1)区域有分辨良好的谱带，分别归属于(UO2)2+单元的ν1模式和(SiO4)4-四面体。硅钙铀矿的特征拉曼谱带位于828.0、808.6和801.8 cm(-1)、909.6和898.0 cm(-1)以及268.2、257.8和246.9 cm(-1)，分别归属于ν1、ν3和ν2(δ)(UO2)2+。预计ν1(UO2)2+和ν1(SiO4)4-会有重合。位于1082.2、1071.2、1036.3、995.1和966.3 cm(-1)的谱带归属于ν3(SiO4)4-。200 - 300 cm(-1)区域的拉曼谱带组归属于ν2(δ)(UO2)2+和UO配体振动。多个谱带表明UO键的不等价性以及ν2(δ)(UO2)2+振动简并性的消除。(SiO4)4-四面体的特征谱带位于470 - 550 cm(-1)区域和390 - 420 cm(-1)区域。这些谱带归属于ν4和ν2(SiO4)4-弯曲模式。这些矿物在2900 - 3500和3600 - 3700 cm(-1)显示出特征性的OH伸缩谱带。
