Abstract

Information on dynamic guest-host interactions is contained in the homogeneous linewidth Γ_hom [1]: where T₁ represents the population decay time of the excited state, and T₂^* the pure dephasing time determined by thermally induced fluctuations of the optical transition frequency. The first term includes all de-excitation steps, i.e. direct de-excitation to the ground state and energy transfer processes from the excited state. If energy transfer does not occur, then T₂^* usually dominates, since T₁ ≫ T₂^*. This is the case for most organic molecules doped in glasses and polymers [1] and some biological model systems at low temperature [2]. By contrast, for many pigment-protein complexes Γ_hom is principally given by population decay, thus T₁ ≪ T₂^* [3].

© 1992 Optical Society of America