Creation of F2+ color centers

摘要

Production of F2+ color centers in alkali halide crystals with densities high enough for efficient use in lasers is achieved by a two-step, highly selective photoionization mechanism. This mechanism is coupled with the use of suitable divalent metal ions as efficient and stable electron traps to allow nearly 100 percent conversion of F2 color centers to F2+ color centers. The two-step photoionization mechanism comprises photo-exciting the F2 color center to the first bound state, which requires lower energy than the corresponding transition for F color centers, then photoionizing the F2 color center from the first bound state, and finally, capturing the electron thus liberated on the divalent metal ions.