Raman spectroscopic study of the multi-anion uranyl mineral schroeckingerite

Abstract

Raman spectroscopy complimented with infrared spectroscopy has been used to study the mineral schroeckingerite. The mineral is a multi-anion mineral and has (UO2)2+, (SO4)2-, and (CO3)2- units in its structure and bands attributed to these vibrating units are readily identified in the Raman spectra. Symmetric stretching modes at 815, 983 and 1092 cm-1 are assigned to (UO2)2+, (SO4)2-, and (CO3)2- units, respectively. The antisymmetric stretching modes of (UO2)2+, (SO4)2- are not observed in the Raman spectra but may be readily observed in the infrared spectrum at 898 and 1180 cm-1. The antisymmetric stretching mode of (CO3)2- is observed in the Raman spectrum at 1374 cm-1 as is also the ν4 (CO3)2- bending modes at 742 and 707 cm-1. No ν2 (CO3)2- bending modes are observed in the Raman spectrum of schroeckingerite. All the spectroscopic evidence points to a highly ordered structure of this mineral.