A method of determination of quantum yields of S_3 -> S_2, S_3 -> S_1, and S_3 -> S_0 intramolecular radiationless transitions

摘要

An effective method for determination of the quantum yields of the S_3 -> S_2, S_3 -> S_1 and S_3 -> S_0 intramolecular radiationless transitions, based on steady-state measurements of absorption, S_2 fluorescence and T_1 phosphorescence or S_1 fluorescence under selective excitation to the S_2 and S_3 states has been described and used for three aromatic thioketones. The results show that in the compounds studied the deactivation of the S_3 state is not strictly sequential and the S_3 -> S_1 as well as, unexpectedly, S_3 -> S_0 transitions occur with relatively high yields. Measurement of the quantum yields of S_3 -> S_2, S_3 -> S_1, and S_3 -> S_0 intramolecular radiationless transitions is essential for the determination of the intramolecular properties of molecules in the S_3 state as well as pathways of their decay.