Theory of the effect of environment fluctuations on intramolecular vibronic transitions

The path integral method is used to calculate the rate of intramolecular electronvibration transitions taking into account the influence of the environmen as the source of random Gaussian forces acting on the vibrational degrees of freedom of moleculi. Evaluation of the generating function of probabilities of many-quantum transitions is reduced to solving integral equations with the kernels which depend upon the form of the correlation function of the Gaussian forces. For the Markovian Gaussian random process the exact expression for the generating function is found. Manifestations of dynamical modulation effects of the environment fluctuations in tunnel and thermostimulated intramolecular transitions are investigated.