Photodissociation of organic compound vapors pumped by pulsed laser radiation

An investigation was made of photodissociation in rarefied molecular vapors of l,4-bis-[2-(5-phenyloxazolyl)] benzene (POPOP), which is an active medium of lasers utilizing organic compound vapors, and also of 2,5-dipheny1-1,3,4-oxadiazole (PPD) and paraterphenyl, which are potential active media for this type of laser. One-photon dissociation of the molecules of these compounds was observed with quantum yields of q = 0.040, 0.17 and 0.017 for POPOP, PPD, and paraterphenyl vapor pumped by λ_p = 266 nm laser radiation and q = 0.018 for POPOP pumped by λ_p = 355 nm radiation. The absence of laser action in the PPD and paraterphenyl vapors was attributed to the considerably more efficient photodissociation of the active molecules compared with that in solutions.