EPR and optical study of Mn 2+-doped lithium hydrogen oxalate monohydrate single crystals

Abstract

EPR study of Mn 2+-doped lithium hydrogen oxalate monohydrate single crystals are done at room temperature. The Mn 2+ spin-Hamiltonian parameters are evaluated employing a large number of resonant line positions observed for different orientations of the external magnetic field. The values of g, A , B , D, E and a are 1.9942±0.0002, 114±2×10 −4, 103±2×10 −4, 180±2×10 −4, 57±2×10 −4 and 7±1×10 −4 cm −1, respectively. The optical absorption study of the crystal is also done. The observed bands are assigned as transitions from the 6A 1g(S) ground state to various excited quartet levels of Mn 2+ ion in a cubic crystalline field. These bands are fitted with four parameters, inter-electronic repulsion parameters ( B and C), crystal field parameter ( D q) and Tree's correction ( α). The values found for the parameters are B=814 cm −1, C=2255 cm −1, D q=780 cm −1, and α=76 cm −1. On the basis of the data obtained, the surrounding crystalline field and the nature of metal–ligand bonding are discussed.