The low-energy onset of CS2 biexponential fluorescence decays

Bioexponential fluorescence decays, which are characteristic of the T 1A2 and V 1B2 states of CS2, are here also observed for the lower-lying R state. They first appear when the (1, 6, 0) vibrational level at T0 = 28 635 cm−1 is excited and are initially due to the multiple excitations that accompany band congestion and line overlap. Decays from the (0, 9, 0) level at T0 = 28 816 cm−1 and all higher vibrational levels are bi- or multiexponential. Their longer-lived components apparently arise from the direct excitation of brightened background levels that lie adjacent to R state ones.