Quantum dynamics of ClH2O- photodetachment: Isotope effect and impact of anion vibrational excitation.

Abstract

Photodetachment of the ClH2O- anion is investigated using full-dimensional quantum mechanics on accurate potential energy surfaces of both the anion and neutral species. Detailed analysis of the photoelectron spectrum and the corresponding wavefunctions reveals that the photodetachment leads to, in the product channel of the exothermic HCl + OH → Cl + H2O reaction, the formation of numerous Feshbach resonances due apparently to slow energy transfer from H2O vibrational modes to the dissociation coordinate. These long-lived resonances can be grouped into two broad peaks in the low-resolution photoelectron spectrum, which is in good agreement with available experiments, and they are assigned to the ground and first excited OH stretching vibrational manifolds of H2O complexed with Cl. In addition, effects of isotope substitution on the photoelectron spectrum were small. Finally, photodetachment of the vibrationally excited ClH2O- in the ionic hydrogen bond mode is found to lead to Feshbach resonances with higher stretching vibrational excitations in H2O.