Picosecond transient Raman spectra of photoexcited 4‐dimethylamino‐4′‐nitrostilbene in polar solvents

Picosecond transient Raman spectra of photoexcited 4‐dimethylamino‐4′‐nitrostilbene in polar solvents (acetonitrile, acetone and benzonitrile) were observed and the decay kinetics of the observed Raman bands were analysed. The observed solvent dependences of the peak positions suggest that the transient Raman bands arise from a non‐radiative charge‐transfer (CT) state. Molecules in the vibrationally excited CT states were also observed by monitoring transient anti‐Stokes Raman scattering. These results indicate that a rapid non‐radiative transition occurs from the lowest allowed singlet state to vibrationally excited CT states.