The Linear and Nonlinear, Raman and Fluorescence Scattering of a Laser Field by Molecules.

A non-perturbation theory on the interaction between quantized laser field and molecules is developed. The photon state are determined by solving the time-dependent Schroedinger equations in an interaction representation. The molecules are proved to respond to the field through molecular eigenstates by creating individual scattering fields which are composed of a Raman and a fluorescence components. The scattering rates, spectra are generally found. The cross sections of Raman scattering, fluorescence scattering of each molecular eigenstate are determined for off-, near - and on-resonance scattering cases. The problem is discussed parallelly in both time and frequency domains. The nonlinear scattering under strong field is also discussed which shows rather different features on the process. The intermediate molecules are discussed in detail. The results are compared to the well known Bixon-Jortner and Lahmani-Tramer-Tric theories. The problems such as the field dependence of the emission, the dephasing, the incoherence and its effect, and the irreversibility are discussed under the new theoretical frame.