Chemical physics of excitation dynamics via amplified spontaneous emission (ASE) laser spike spectroscopy in substituted phenyloxazoles

A spectroscopic study of the fluorescence, amplified spontaneous emission (ASE), and gain spectra is made, testing for UV lasing from several phenyloxazoles. ASE laser spikes occur at 333 and 349 nm for 2-phenylbenzoxazole (PBO), 356 and 374 nm for 2,5-diphenyloxazole (PPO) and 365 and 385 nm for 2-(1-naphthyl)-5-phenyl-1,3,4-oxadiazole (α-NPD), all in hydrocarbon solution at 298 K. For DPOPOP, 1,4-bis(4-methyl-5-phenyloxazol-2-yl)benzene, the ASE laser spike occurs at 420 nm. The gain coefficients range from 5 to 10 cm−1. Unorthodox features in the ASE spectroscopy serve as a clue to the electronic excitation dynamics of complex composite molecular systems.