AN EXACTLY SOLUBLE MODEL OF EXCITON-PHONON COUPLING SYSTEMS

In the study of nonlinear optical response of polymers, the polymer is usually characterized as an exciton-phonon coupling system with a fin ite number of phonon modes. Such a system is now solved exactly and un expected features of the energy spectrum are revealed. When such a sys tem interacts with weak electromagnetic radiation, a red shift of emis sion frequencies following exciton recombination results. Phonon-numbe r dependent selection rules for the electric dipole transition are als o found and discussed.