Photo-stability of laser dye solutions under Copper-vapour-laser excitation

The photo-stability of laser dyes, Rhodamine-BG, Rhodamine-B, and Kiton-Red , under high repetition rate (6.3 kHz) Copper-vapour-laser (CVL) irradiatio n has been investigated. Exhaustive photo-bleaching of these dyes in differ ent solvents has been carried out to study the extent to which the dye phot o-degraded products would interfere with the lasing process in high-power C VL-pumped dye lasers. Our results indicate that the photo-degradation of dy es occurs predominantly through excited-state intermolecular reactions, inv olving the singlet state, rather than the process of nonlinear optical abso rption in individual molecules.