Optical Spectra of Tm3+ Ions in ZnSe:Tm, Li and ZnSe:Tm, Cu Crystals

The absorption and luminescence spectra were observed below 77°K by using a high resolution spectrograph. The crystal field spectra show that the structures of some Tm 3+ centers are common to both of ZnSe:Tm, Cu and ZnSe:Tm, Li crystals. One of the common centers has a cubic symmetry and the crystal field parameters A 4 0 < r 4 >=15.1 cm -1 and A 6 0 < r 6 >=-2.5 cm -1 . The Tm 3+ ion in this center shows strong emission. Discussions on the model of this center and on the excitation mechanism are given.