Experimental and theoretical studies of quantum beats in fluorescence

The effect of collision on quantum beat is studied theoretically by applying the density matrix method. As an application of this theory, we analyze the experimentally observed quantum beat appearing in the time-resolved fluorescence profiles of biacetyl. In order to explain complicated fluorescence beating patterns, we present a three-state model and several important molecular properties are mapped onto this model. We also investigate how quantum beat patterns appear as a function of the number of the triplet states that are involved in the interaction with the singlet state.