Measurements of the subpicosecond relaxation rates of the first excited singlet states of some pseudoazulenes in solution Original Research Article

The subpicosecond population decay times of the S1 states of a number of pseudoazulenes have been measured in solvents of different polarity, using a two-photon, two-color, pump-probe method. The nonradiative decay rates of the S1 states vary exponentially with the S1–S0 energy gap, and the results are interpreted in terms of the energy gap law formalism of radiationless transition theory. The behavior of the excited states of the pseudoazulenes is compared with that of azulene and its derivatives.