Resonance Fluorescence in Gases and Molecular Crystals

Abstract

A general theoretical description is derived for the resonance fluorescence of dilute gases and molecular single crystals with special emphasis on optical rotation spectra. The validity of previous theoretical work on dilute gases is confirmed by proving that the damping constants connecting excited states on different molecules are zero. It is shown that the intensities of optical rotation spectra of molecular crystals are much larger than the corresponding quantities for gases. An important theoretical prediction is that the natural line breadth of a resonance fluorescence emission band belonging to an exciton state in a molecular crystal should be larger than the width of the corresponding optical absorption line. The dependence of the intensity of the optical rotation spectrum on the relative orientation of the crystal with respect to the incident beam of light is discussed.