Theoretical calculation of the vibrational state dependent photodetachment spectra of X−H2O, X = F, Cl, Br

Abstract

Vibrational spectra of X⁻H₂O (X = F, Cl, Br) were simulated using full dimensional vibrational calculations using quantum chemistry potential energy surfaces. Furthermore, utilizing the reflection approximation, we simulated the photodetachment spectra obtained from different vibrational excited states. From these spectra, we can observe changes in the hydrogen bond interaction between the anion and the neutral X⋯H₂O system. Notably, for F⁻H₂O, the excitation of the ionic hydrogen bonded (IHB) OH stretching vibration generates a large tail on the low energy side of the photodetachment spectra compared to the detachment from the zero-point vibration state. This shows that the IHB OH stretching vibration of F⁻H₂O causes charge delocalization from F⁻ to the oxygen atom in H₂O, and that the photodetachment from FH⋯OH⁻ occurs at lower energies.