Non-coherent exciton migration in J-aggregates of the dye THIATS: exciton–exciton annihilation and fluorescence depolarization

Exciton–exciton annihilation (EEA) in J-aggregates of 3,3′-disulfopropyl-5,5′-dichloro-9-ethylthiacarbocyanine in solution at room temperature and at 77 K was related to incoherent exciton migration within large aggregate domains. Inside a domain, the rate constant for EEA was estimated to be at least 1.5 times smaller than that of exciton decay. The experimental results were incompatible with one-dimensional incoherent exciton transport. The intensity dependence of the fluorescence anisotropy decay was assigned to EEA. At 77 K and in the absence of EEA, the average angle of the transition dipole changed less than 25° during exciton migration over a domain.