Raman spectroscopic study of the uranyl mineral pseudojohannite Cu6.5[(UO2)4O4(SO4)2]2(OH)5•25H2O

Raman spectra of pseudojohannite were studied and related to the structure of the mineral. Observed bands were assigned to the stretching and bending vibrations of (UO2)(2+) and (SO4)(2-) units and of water molecules. The published formula of pseudojohannite is Cu-6.5(UO2)(8)[O-8](OH)(5)[(SO4)(4)]center dot 25H(2)O. Raman bands at 805 and 810 cm(-1) are assigned to (UO2)(2+) stretching modes. The Raman bands at 1017 and 1100 cm(-1) are assigned to the (SO4)(2-) symmetric and antisymmetric stretching vibrations. The three Raman bands at 423,465 and 496 cm(-1) are assigned to the (SO4)(2-) nu(2) bending modes. The bands at 210 and 279 cm(-1) are assigned to the doubly degenerate nu(2) bending vibration of the (UO2)(2+) units. U-O bond lengths in uranyl and O-H center dot center dot center dot O hydrogen bond lengths were calculated from the Raman and infrared spectra. Copyright (C) 2009 John Wiley & Sons, Ltd.