Fluorescence from molecules between mirrors

A quantum theory calculation is presented of the fluorescence lifetime of an oriented molecule held at a fixed position between a pair of parallel infinite mirrors. When the molecule lies close to one of the mirrors and the mirror—mirror separation greatly exceeds λ, the wavelength of the transition, the results of the classical theory of Kuhn are recovered. In particular it is shown that the molecule does not fluoresce during a period comparable to the half-life of the isolated molecule if the transition is polarized parallel to the mirror. It fluoresces at twice the isolated molecule rate if the transition dipole is perpendicular to the mirror. A brief discussion is given of the problems of molecular interactions with real metal surfaces and the proton fields of optical wave guides.