Optical absorption spectrum of Ni2+ ion doped in synthetic lecontite

The optical absorption spectrum of Ni²⁺ ion doped in lecontite (sodium ammonium sulphate dihydrate) single crystal has been studied at room and liquid air temperatures. All the bands could be assigned assumingO _h symmetry for the Ni²⁺ ion in the crystal. The splitting of³ T _1g (F) band at liquid air temperature has been attributed to spin-orbit interaction. The crystal field and spin-orbit parameters derived areD _q=1000 cm^?1;B=740 cm^?1;C/B=4.27 and ζ=600 cm^?1. All the bands observed show a blue shift when the crystal was cooled to liquid air temperature.