Photofragment vector correlations in vibrationally mediated photodissociation. A new angle on intramolecular vibrational redistribution

Abstract

Vector correlations in OH fragments, generated through vibrationally mediated two-photon photodissociation of H₂O₂ at ca. 750 nm, have been determined through Doppler-resolved LIF spectroscopy. The new measurements, together with a knowledge of the photofragment quantum-state distributions and an understanding of the dynamics of the direct single-photon dissociation, have allowed a detailed insight into the intramolecular dynamics in the vibrationally excited ground state. In particular, it has been possible to estimate the average vibrational mode composition after IVR over a nanosecond period. Both angle bending and torsion, as well as large-amplitude O—O stretching motions, are found to be excited. Extension of this experiment into the picosecond or sub-picosecond timescale should offer the opportunity of monitoring IVR processes in real time.