Feshbach Resonances in the Vibrationally Excited F + HOD(vOH/vOD = 1) Reaction Due to Chemical Bond Softening.

Experiments and theories showed the ground-state reaction F + H2O → HF + OH possesses Feshbach resonances trapped in the hydrogen bond well in the product region. However, it is not clear whether F + H2O and its isotopic analogues have the same Feshbach resonances caused by chemical bond softening as those in the F + H2/HD. Here, we reported state-to-state quantum dynamics studies of the F + HOD(vOH = 1) → HF + OD and F + HOD(vOD = 1) → DF + OH reactions on an accurate neural network potential energy surface. Detailed analysis reveals that the course of the title reactions is dominated by the Feshbach resonance states trapped in the peculiar HF(v'=3)-OD/DF(v'=4)-OH vibrationally adiabatic potential well created by the HF/DF bond softening, which can only be accessed via the HOD(vOH = 1)/HOD(vOD = 1) reaction pathway. Therefore, we confirm the wide existence of chemical bond softening resonances in reactions involving vibrationally excited molecules.