Vibrationally mediated photodissociation of H 2O 2 (4 vOH): rotational state dependent photodissociation cross sections and vibrational state mixing

Abstract

A reinvestigation of the vibrationally mediated photodissociation spectrum of the 3rd OH stretching overtone (4 v OH) of jetcooled H 2O 2, first observed by Crim and co-workers, reveals anomalous double resonance spectral intensities compared with those observed via high-resolution absorption spectroscopy. The origin of these intensity perturbations is traced to J' KaKc level dependent variations in the photodissociation cross section, δ 00, out of the intermediate overtone state. The photofragment OH(X, v=0) rotational state distribution generated by photodissociation of H 2O 2 (4 v OH, J' KaKc=2 02) has been determined. Combined with the relative cross-section data, these results imply that delocalization of the overtone state wavefunction into wideamplitude OO stretching regions of the ground state is profoundly influenced by parent molecular rotation, primarily about the a and b axes. The intermediate state with J'=0 is shown to be much more highly localized, and hence more likely to display mode selective behaviour, than its J' >0 counterparts.