Optical absorption of Ni2+-doped NaF

Optical absorption of Ni2+-doped NaF at 300 and 80°K is reported. The observed bands have been assigned to transitions from the ground state 3A2g(F) to the excited states 3T2g(F), 3T1g(F), 3T1g(P) and 1Eg(D). At 80°K a new band appears on the higher energy side of the 1Eg(D) band at a separation of 488 cm−1. The origin of this new band is attributed to the excitation of a multiphonon mode. The observed band energies at 80°K have been fitted with the parameters B, C and Dq and the values obtained are B = 950 cm−1, C = 4210 cm−1 and Dq = 770 cm−1.