Relaxation of excited molecules in a medium with memory at short and long times

Abstract

Two qualitatively different approaches to the dynamics of vibrational wave packets in the presence of medium induced relaxation, with taking into account relaxation memory effects and without taking them into account (Makovian approximation) were compared for a molecular system with one vibrational degree of freedom (the Morse oscillator) in a medium. The time evolution of the populations of levels, mean system energy, and response of "pumping-probing" experiments were calculated. It was found that, as distinct from the Markovian approximation, the approach including memory effects can predict the evolution of a molec ular system satisfying the detailed equilibrium principle. The two approaches specified also predict the exist ence of a qualitative difference of phase characteristics in the behavior of the system at short times.