FEMTOSECOND ABSORPTION AND EMISSION-SPECTROSCOPY OF THE DCM LASER-DYE

The results of a femtosecond laser investigation of the photophysical and photochemical properties of the DCM styryl laser dye molecule are reported. Femtosecond pump-probe experiments (absorption/gain spectros copy using a white light continuum and up-conversion fluorescence spec troscopy) show a red shift of the gain and emission spectra and a blue shift of the S-1-->S-N absorption band only due to a fast reorganizat ion of the solvent cage around the highly polar fluorescent first sing let excited state of DCM. This first complete study (spontaneous emiss ion, gain and absorption) of DCM with a pump-probe intercorrelation fu nction around 300 fs (FWHM) demonstrates that the hypothesis of a tran sition from a locally excited (LE) to a twisted intramolecular charge transfer (TICT) state is not valid for DCM.