Formation of Self Trapped Excitons and F Centers in Picosecond Range in KI Crystals

Abstract

By using a mode locked ruby laser, it has been shown that the self trapped excitons in KI crystals are created with a time constant of 210±15 psec at liquid helium temperature, and F centers are created with a time constant of 11±9 psec at room temperature, respectively. An additional absorption band growing with a time constant of 75±25 psec at liquid helium temperature and of 10±10 psec at room temperature was observed around 694 nm. This absorption band is bleached with a decay time of about 10 psec at both temperatures, but its origin was not clear. Formation processes of the self trapped excitons and of the F centers are discussed.