Simulation of intramolecular dynamics at transformation of two light pulses by molecules of active media of photochemical lasers

Using a numerical solution of a system of equations for matrix elements of file-level model molecule density operator time dependencies of population on its states at different values of two irradiation pulses parameters (the pump pulse and the dump (or probe) pulse) and constants, determining rates of induced radiative transitions of the molecule, and radiative and nonradiative decays of the molecular states are calculated. The values of these constants were taken, in particular, close to these of the corresponding constants of molecules with intramolecular hydrogen bond as the 3-hydroxyflavone (3-HF) molecule. Values of irradiation pulses parameters are obtained, at which after enol-keto photoisomerization, induced by pump pulse, dump pulse induces molecular transition from excited electronic state in keto-form to ground state in this (ldquotautomericrdquo) form. This transition is accompanied by stimulated emission with a frequency of ldquotautomericrdquo fluorescence. Examples of periodic change of intensity of the stimulated emission are given, the frequency of oscillations of fluorescence intensity being proportional to dump pulse intensity.