Picosecond time-resolved photoelectron spectroscopy as a means of elucidating mechanisms of intramolecular vibrational energy redistribution in electronically excited states of small aromatic molecules

Preliminary findings are reported following the detailed analysis of intramolecular vibrational energy redistribution (IVR) in S₁ para-fluorotoluene following the excitation of one quantum in the CF stretching mode ν₇. It is shown that the method proposed has the potential to enable not only the determination of a rate constant for IVR, but also the identification of the dark states into which energy has redistributed. In addition energy flow has been observed from a bright state (11¹) previously thought to be below the onset for IVR in this molecule, and evidence of mode-specificity in the IVR process.