F-H Pair Creation from Localized Exciton in KBr:I

Color center formation has been investigated in KBr:I crystals at 10 K under one photon pulse excitation into the localized exciton band by using ArF-excimer laser light. F and H centers are produced and their absorption spectra agree with those of F and H centers in pure KBr colored with X-rays. From time dependent measurements, it is found that F and H centers are simultaneously created and part of them decay with time constants of ∼20 µs and ∼100 µs by the mutual recombination. The transient behavior of these centers is similar to that of F and H centers in pure KBr. It is concluded that F and H centers are created in pairs from I - -localized excitons and the H centers thus created are not associated with I - ions.