Subpicosecond time-dependent Stokes shift studies of the donor-acceptor compound PIDMP in ethereal solution

The dynamic Stokes shift of the donor-acceptor compound, PIDMP, in its lowest excited charge transfer state has been studied in a series of ethereal solvents at room temperature with a time resolution of about 300 fs. By means of the fluorescence upconversion method dynamic Stokes shifts of up to 2400 cm−1 on a subpicosecond time scale have been resolved. The observed dynamic Stokes shifts are due to solvation relaxation for which the kinetics is determined by rotational diffusion motions of the solvent molecules.