Triplet quantum yield determination by picosecond laser double-pulse fluorescence excitation Original Research Article

The quantum yields of S1 → T1 triplet formation of some organic dyes are determined by picosecond double-pulse laser excitation and time-resolved fluorescence detection. The second pulse fluorescence signal is reduced due to first pulse induced singlet-triplet intersystem crossing. Disturbances due to higher excited state triplet-singlet back transfer are minimized by proper laser pulse duration and pulse energy density adjustment. The saturation energy density of triplet ground state depopulation has to be higher than the saturation energy density of singlet ground state depopulation, and the energy density of the second excitation pulse should be comparable to or less than the saturation energy density of ground state depopulation.