Calculation of some characteristics of stimulated emission from active media of lasers based on organic compounds

Quantum chemistry methods are used to calculate the cross section for stimulated emission σ(ν) and the Einstein coefficients B(ν) for several substituted forms of oxazole, oxadiazole, naphthalene, pyrene, and other molecules. It is shown that introduction of electron-donor and phenylethynyl substituents into molecules of heteroaromatic and aromatic compounds, respectively, increases considerably both σ(ν) and B(ν) and imparts lasing ability to nonlasing compounds. A criterion is established for the oscillator strength of an electronic transition which must be satisfied if a compound is to have the lasing ability.