PICOSECOND VIBRATIONAL DYNAMICS OF SEVERAL S-1 BANDS IN JET-COOLED P-DIFLUOROBENZENE

Picosecond pump-probe threshold photoelectron spectroscopy was used to investigate the vibrational dynamics of four vibrational bands in the S-1 state of p-difluorobenzene in the range 2000 to 2900 cm(-1). In this energy region the vibrations exhibited intermediate case restricted vibrational dynamics as evidenced by observed quantum beats as well as irreversible statistical limit decay. More complete coverage of the S-1 state was prohibited by the wavelength restrictions on both the pump and probe laser wavelengths required in the experiment. The observed restricted vibrational redistribution is in contrast to the very rapid irreversible decays inferred from-room temperature, high pressure chemical timing experiments on the same molecular bands.:The differences are discussed