Optical spectrum of Cr3+in the spinel LiGa5O8

The optical absorption and luminescence spectra of chromium ions in the LiGa 5 O 8 spinel are investigated. Measurements are made in the temperature range 1.6-300K. The absorption spectra consist of broad (split into three) spin-allowed bands connected with the transitions 4 A 2 to 4 T 2 and 4 A 2 to a 4 T 1 , and sharp lines connected with spin-forbidden transitions from the ground state 4 A 2 to the excited states 2 E, 2 T 1 and 2 T 2 . The results from absorption measurements together with the results of EPR measurements are interpreted in the framework of crystal-field theory.