Crystal Field and Spin-Orbit Effects in the Optical Spectrum of Ni²⁺ Ions Doped in Ammonium Aluminium Sulphate Single Crystal

Abstract

The optical absorption spectrum of Ni²⁺ ions doped in ammonium aluminium sulphate single crystal has been studied at room and liquid air temperatures. From the nature and otner details of the spectrum, the crystal is found to have an octahedral symmetry. The fine splitting of the ³T_1g (F) band at liquid air temperature has been interpreted due to spinorbit interaction.

A weak band observed at 16845 cm⁻¹ has been assigned to the vibrational mode of SO₄ molecule.

From a detailed analysis of the bands of the spectrum, the crystal parameters derived are: B = 678 cm⁻¹; C = 3.75 B; Dq = 1030 cm⁻¹ and ξ = 600 cm⁻¹