title: Dynamical resonances accessible only by reagent vibrational excitation in the F + HD->HF + D reaction.
abstract: Experimental limitations in vibrational excitation efficiency have previously hindered investigation of how vibrational energy might mediate the role of dynamical resonances in bimolecular reactions. Here, we report on a high-resolution crossed-molecular-beam experiment on the vibrationally excited HD(v = 1) + F → HF + D reaction, in which two broad peaks for backward-scattered HF(v' = 2 and 3) products clearly emerge at collision energies of 0.21 kilocalories per mole (kcal/mol) and 0.62 kcal/mol from differential cross sections measured over a range of energies. We attribute these features to excited Feshbach resonances trapped in the peculiar HF(v' = 4)-D vibrationally adiabatic potential in the postbarrier region. Quantum dynamics calculations on a highly accurate potential energy surface show that these resonance states correlate to the HD(v' = 1) state in the entrance channel and therefore can only be accessed by the vibrationally excited HD reagent.
authors.affiliation: State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.forename: Tiangang
authors.initials: T
authors.lastname: Yang
authors.forename: Chunlei
authors.initials: C
authors.lastname: Xiao
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Sun
authors.forename: Long
authors.initials: L
authors.lastname: Huang
authors.forename: Dongxu
authors.initials: D
authors.lastname: Dai
authors.forename: Xueming
authors.initials: X
authors.lastname: Yang
authors.forename: Dong H
authors.initials: DH
authors.lastname: Zhang