ESR and Optical Absorption Study of the Tl0 (1) Center in NaCl. A Stable Laser‐Active Type Defect

The properties are given of the laser‐active type Tl0(l) center in NaCl as derived from an ESR and optical study. The higher thermal and optical stability of this center in NaCl compared to KCl, RbCl, and KBr suggests that it could be a candidate for a viable laser‐active system. The procedure for optimal production of Tl0(l) in NaCl is distinctly different from that known for this center in the other hosts. Optical absorption bands at 470 and 1060 nm, both possessing σ‐character, are attributed to the Tl0(l) center in NaCl and correspond to the so‐called “F‐like” and the pump laser transitions, respectively, of Tl0(l) in the other hosts.