The spectrum of F-center creation was measured in Tl-doped material by using vacuum ultra-violet radiation (7 to 32eV). It was found that, at 295K, the creation efficiency of a stable F center was especially high at 17 to 19eV and 29 to 31eV; where the absorption of 1 photon led to the formation of both an electron-hole pair (or 2 pairs) and an exciton. Thermal annealing of the F centers took place at temperatures ranging from 240 to 470K; at the same time as Cl3- centers, which could be easily created at 240 to 300K due to the association of H centers, holes and cation vacancies.

A.Lushchik, M.Kirm, I.Kudryavtseva, E.Vasilchenko, C.Lushchik: Materials Science Forum, 1997, 239-241, 581-6