Emission centres in anthracene single crystals. Effects of irradiation

Abstract

The 5 K fluorescence of highly purified anthracene single crystals shows, in addition to exciton (collective) emission, several X-trap lines which depend on the mode of crystal preparation and mounting. 365 nm irradiation at room temperature, under conditions leading to formation of photodimer, removes most X-trap emissions. At the same time, new photoinduced emission lines appear, one of which, with origin at 24 989 cm^–1(vac.), is destroyed by 365 nm radiation at 5 K. The role of X-traps and photoinduced X-traps is discussed.