Efficiency of lasers utilizing vapors of complex organic compounds subjected to hard ultraviolet (266 nm) pumping

Measurements were made of the efficiency of stimulated emission in the range 329–400 and 500 nm by a series of complex organic compounds in gaseous mixtures with pentane (1.5×10²¹ cm^–3) when the vapor was excited by the fourth harmonic of neodymium laser radiation (266 nm, 5 nsec, 20 mJ). Lasing of PPD (340 nm) and PBD (352 nm) vapors was observed for the first time. The highest lasing efficiency was obtained for vapors of 1,4-di-(benzoxazole-2'-yl)benzene (20%), PBD (13%), and PPF (3%). Lasing was found possible in the case of coumarin 6 and 7-diethylamino-3(2'-benzoxazolyl)-coumarin vapors mixed with ether (1.5×10²¹ cm^–3) and subjected to hard ultraviolet (266) nm pumping. A study was made of the dynamics of the pump absorption, lasing, and fluorescence. Low-threshold transverse stimulated scattering of the pump radiation was observed for the first time for active media based on complex organic molecules. The fluorescence lifetime was estimated for gaseous mixtures under working conditions. An analysis was made of the characteristics of the chemical structure of those compounds which exhibited a high lasing efficiency as vapors.