Raman spectroscopy of smithsonite

Raman spectroscopy at both 298 and 77 K has been used to study a series of selected natural smithsonites from different origins. An intense sharp band at 1092 cm −1 is assigned to the CO 3 2− symmetric stretching vibration. Impurities of hydrozincite are identified by a band around 1060 cm −1 . An additional band at 1088 cm −1 which is observed in the 298 K spectra but not in the 77 K spectra is attributed to a CO 3 2− hot band. Raman spectra of smithsonite show a single band in the 1405–1409 cm −1 range assigned to the ν 3 (CO 3 ) 2− antisymmetric stretching mode. The observation of additional bands for the ν 3 g modes for some smithsonites is significant in that it shows distortion of the ZnO 6 octahedron. No ν 2 bending modes are observed for smithsonite. A single band at 730 cm −1 is assigned to the ν 4 in phase bending mode. Multiple bands be attributed to the structural distortion are observed for the carbonate ν 4 in phase bending modes in the Raman spectrum of hydrozincite with bands at 733, 707 and 636 cm −1 . An intense band at 304 cm −1 is attributed to the ZnO symmetric stretching vibration.