SPECTROSCOPIC INVESTIGATIONS ON POLYDYMITE

Electron Probe Micro Analysis (EPMA), optical absorption and IR spectra of NL(II) bearing polydymite mineral are investigated. The optical absorption spectrum in UV-VIS region is predominantly characteristic of Ni(II) in octahedral symmetry. The observed bands are assigned to different transitions arising from the ground state (3)A(2g)(F) to various excited states. The crystal held parameters are evaluated as Dq = 900, B = 840 and C = 3360 cm(-1). A group of bands in the region 4149 cm(-1) - 4425 cm(-1) are attributed to Ni(II) ion in tetrahedral symmetry. This is in tune with the crystal structure of polydymite in which the Ni(II) is present both in octahedral and tetrahedral sites.