Excited state dynamics of Michler's ketone: a laser flash photolysis study

Steady state absorption and fluorescence as well as the time resolved absorption studies in the pico and subpicosecond time domain have been performed to characterize the excited singlet and triplet states of Michler's ketone (MK). The nature of the lowest excited singlet (S-1) and triplet (T-1) states depends on the polarity of the solvent - in nonpolar solvents they have either pure n pi* character or mixed character of n pi* and pi pi* states but in more polar solvents the stares have CT character. Concentration dependence of the shapes of the fluorescence as well the excited singlet and triplet absorption spectra provide the evidence for the association of the MK molecules in the ground state.