Quantum calculations of the photoelectron spectra of the OH−·NH3 anion: implications for OH + NH3 → H2O + NH2 reaction dynamics

Abstract

We present the results of quantum dynamics calculations for analyzing the experimentally measured photoelectron spectra of the OH⁻·NH₃ anion complex. Detachment of an excess electron of OH⁻·NH₃ initially produces a molecular arrangement, which is close to the transition-state structure of the neutral OH + NH₃ → H₂O + NH₂ hydrogen abstraction reaction due to the Franck–Condon principle, and thus finally leads to the OH + NH₃ or H₂O + NH₂ asymptotic channel. We used both the path integral method and the reduced-dimensionality quantum wave packet method to simulate the photoelectron spectra of the OH⁻·NH₃ anion. The calculated spectra were found to be in qualitative agreement with the experimental spectra. It was found that the photodetached complex mainly dissociates into the OH + NH₃ channel; however, we found that the hydrogen exchange process also contributes to the photodetachment spectra.