Franck–Condon simulations of transition-state spectra for the OH + H2O and OD + D2O reactions

Abstract

We present the results of quantum wave packet calculations performed to analyze the experimental transition-state spectra for the OH + H₂O and OD + D₂O reactions based on photodetachment of the H₃O₂⁻ and D₃O₂⁻ anions. We used a reduced-dimensionality model in which four normal-mode coordinates were considered for the neutral transition state. High-level ab initio potential energy surfaces were used for both the neutral and anionic states. The calculated spectra were found to be in reasonable agreement with the experimental spectra. The present study confirms that the vibrational progression observed experimentally is associated with the antisymmetric motion of the transferred H/D atom. We also found that the O–O stretching motion plays an important role in the transition-state dynamics. The influence of vibrational excitation of the H₃O₂⁻ and D₃O₂⁻ anions on the photodetachment spectra was also investigated.