Imitrines. IV. New laser compounds in the imitrine class operating in the 482–618 nm range

Lasing was achieved in solutions of 19 new dyes belonging to the imitrine class. The lasing was observed in the wavelength range 482–618 nm when the dyes were pumped by the third (355 nm) and fourth (266 nm) harmonics of a neodymium laser. In the case of imitrines 27, 38, and 41 (I27, I38, and I41) the lasing efficiency was in excess of 20%; for an ethanol solution of I27, it exceeded the quantum efficiency of fluorescence. Lasing was observed in the gaseous phase using I41 vapor (522 nm) mixed with ether at the pressure of 35 atm. Similarity of the lasing characteristics of imitrines and coumarins was analyzed.