9 research outputs found
Effects of Solute-Solvent Interactions on Radiationless Decay of Thioketones Excited to Their S- and T-States
Spectral and photophysical properties of a few aromatic thioketones in their S- and T-states, in particular those determined by their interactions with solvents, are discussed. The reasons for a drastically different behaviour of thioketones in interactions with benzene as well as saturated hydrocarbons and perfluoroalkanes are analysed in more detail. Results of the time-resolved transient absorption measurements in the pico- and nanosecond time scale are given. An analysis of these results proves that a product of the decay of the S-state of xanthione in benzene is a new transient (τ ≥ 60 ps) individuum which, regarding the system properties and the conditions of the experiment, has been identified as an exciplex in S-state formed as a result of an efficient interaction with benzene molecule. Also in xanthione//alkane systems the involvement of a transient individuum was proved. Most probably, this individuum was a thioketyl radical which could be formed by hydrogen abstraction from a hydrocarbon molecule by xanthione in the S-state. Such individua act as intermediates in passing excitation to the triplet states of thioketones and are effective channels of the S-state decay. The changes observed in the transient absorption spectra of xanthione in CH in the time range of 10-10 s can be attributed to the formation of an excimer in the T-state as a result of the T-state selfquenching