Raman spectroscopic study of the uranyl selenite mineral marthozite Cu[(UO2)3(SeO3)2O2].8H2O

The mineral marthozite, a uranyl selenite, has been characterised by Raman spectroscopy at 298 K. The bands at 812 and 797 cm(-1) were assigned to the symmetric stretching modes of the (UO2)(2+) and (SeO3)(2) units, respectively. These values gave the calculated U-O bond lengths in uranyl of 1.799 and/or 1.814 angstrom. Average U-O bond length in uranyl is 1.795 angstrom, inferred from the X-ray single crystal structure analysis of marthozite by Cooper and Hawthorne. The broad band at 869 cm(-1) was assigned to the v(3) antisymmetric stretching mode of the (UO2)(2+) (calculated U-O bond length 1.808 angstrom). The band at 739 cm(-1) was attributed to the v(3) antisymmetric stretching vibration of the (SeO3)(2-) units. The v(4) and the v(2) vibrational modes of the (SeO3)(2-) units were observed at 424 and 473 cm(-1). Bands observed at 257, and 199 and 139 cm(-1) were assigned to OUO bending vibrations and lattice vibrations, respectively. O-H...O hydrogen bond lengths were inferred using Libowiztky's empirical relation. The infrared spectrum of marthozite was studied for complementation. Copyright (C) 2008 John Wiley & Sons, Ltd.