Picosecond absorption studies of intermolecular electronic energy transfer in micellar systems. II. Polarization-dependent studies of energy migration and energy trapping at low donor excitation densities

Abstract

A picosecond excite-and-probe beam investigation on intermolecular electronic energy transfer (EET) between dye molecules in one-component systems (electronic energy migration - EM) and two-component systems (electronic energy trapping - ET) is presented and compared with existing theories for EET in restricted volumes. The experiments were carried out on a transient absorption spectrometer based on synchronously pumped dye laser (pulse duration 5 ps). Donor excitation density was less than 1%. In the case of ET good agreement has been obtained with the Förster theory, in which in addition an inhomogeneous spatial distribution of the dye molecules has been considered (part I of this study). In the case of EM direct evidence for the theory of Ediger and Fayer has been obtained by measuring the polarization anisotropy at early times after excitation.