Mixed Quantum-Classic Intramolecular Dynamics at Light Transformation by Molecules

摘要

The time-dependent population probability of the excited electronic state in a two-level electronic subsystem of a molecular model in the monochromatic light field is investigated by a mixed quantum-classic method.The dynamics of the electronic subsystem of the molecule,radiation field,and their interaction are described using the decay theory of closely coupled unstable states of quantum systems.The classic field-free dynamics of nuclei are defined By Born-Oppenheimer quadratic potentials.Radiative coupling between "dressed"states and radiative decay of the excited electronic state of the molecule are taken into account.The differential equation of the second order by time for the probability amplitude of the excited electronic-state population is obtained with the consistent description of the adiabatic dynamics of nuclei.The results of numerical computation of this equation were used to describe the time-dependent population rpobability of the excited electronic state of the molecule in terms of"vertical"transitions between dressed states of common system:the molecule and radiation field.On the basis of a few obtained examples of adiabatic modulation of the opoulation of the excited electronic state,conclusions were made on corresponding intensity and spectrum of scattered radiation.The partial agreement and discrepancy of these conclusions in the frameworks of mixed quantum-classic theory with corresponding conclusions in the frameworks of rigorous quantum theory were pinpointed.The comparison severed as grounds for new conclusions concerning a degree of fitness of classic treatment of the nuclear dynamics of molecule under various conditions of light transformation by molecules.