Molecular theory of optical polarization and light scattering in dielectric fluids. I. Formal theory

Abstract

A molecular theory, based on first principles, is introduced for the systematic study of the effects of intermolecular forces on optical properties of dielectric molecular fluids. This theory covers a broad range of applications, including (polarized and depolarized) Rayleigh and Raman scattering, absorption spectra, and nonlinear optics. A canonical transformation is presented by which externally applied coherent fields can be separated from internal radiation fields, thus enabling the introduction of radiative corrections (such as retardation) to the intermolecular forces. The polarization of the medium is expressed in terms of a manybody polarizability (or nonlocal susceptibility) operator. The latter quantity contains implicitly all so-called local-field effects (modification of the molecular polarizability by electromagnetic fields due to neighboring molecules). The dipolar contributions, when summed to all orders, yield the familiar Lorentz-Kirkwood factor, involving the retarded dipole tensor.