SPECTROSCOPIC INVESTIGATIONS ON POLYDYMITE

Electron Probe Micro Analysis (EPMA), optical absorption and IR spectr a of NL(II) bearing polydymite mineral are investigated. The optical a bsorption spectrum in UV-VIS region is predominantly characteristic of Ni(II) in octahedral symmetry. The observed bands are assigned to dif ferent transitions arising from the ground state (3)A(2g)(F) to variou s excited states. The crystal held parameters are evaluated as Dq = 90 0, 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 symmetr y. This is in tune with the crystal structure of polydymite in which t he Ni(II) is present both in octahedral and tetrahedral sites.