Theory of fluorescence depolarization of dimers from the nonlinear Schrödinger equation

Abstract

Strong interactions with vibrations give rise to nonlinearities in the transfer of energy or excitation in quantum systems, with resulting polaronic and solitonic phenomena. With the help of exact solutions of a discrete nonlinear Schrödinger equation obtained recently for a two-site system, we study the effects of such nonlinearities in fluorescence depolarization experiments. The system investigated is a collection of noninteracting molecular dimers subjected to a linearly polarized light beam of variable orientation (of the polarization direction), and the observable studied is the degree of polarization of fluorescence emitted by the dimers. Results differing substantially from their linear counterparts are shown to emerge, and clear manifestations of nonlinearity are predicted.