title: Depression of reactivity by the collision energy in the single barrier H + CD4 -> HD + CD3 reaction.
abstract: Crossed molecular beam experiments and accurate quantum scattering calculations have been carried out for the polyatomic H + CD(4) --> HD + CD(3) reaction. Unprecedented agreement has been achieved between theory and experiments on the energy dependence of the integral cross section in a wide collision energy region that first rises and then falls considerably as the collision energy increases far over the reaction barrier for this simple hydrogen abstraction reaction. Detailed theoretical analysis shows that at collision energies far above the barrier the incoming H-atom moves so quickly that the heavier D-atom on CD(4) cannot concertedly follow it to form the HD product, resulting in the decline of reactivity with the increase of collision energy. We propose that this is also the very mechanism, operating in many abstraction reactions, which causes the differential cross section in the backward direction to decrease substantially or even vanish at collision energies far above the barrier height.
authors.affiliation: State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, 116023, PR China.
authors.forename: Weiqing
authors.initials: W
authors.lastname: Zhang
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhou
authors.forename: Guorong
authors.initials: G
authors.lastname: Wu
authors.forename: Yunpeng
authors.initials: Y
authors.lastname: Lu
authors.forename: Huilin
authors.initials: H
authors.lastname: Pan
authors.forename: Bina
authors.initials: B
authors.lastname: Fu
authors.forename: Quan
authors.initials: Q
authors.lastname: Shuai
authors.forename: Lan
authors.initials: L
authors.lastname: Liu
authors.forename: Shu
authors.initials: S
authors.lastname: Liu
authors.forename: Liling
authors.initials: L
authors.lastname: Zhang
authors.forename: Bo
authors.initials: B
authors.lastname: Jiang
authors.forename: Dongxu
authors.initials: D
authors.lastname: Dai
authors.forename: Soo-Ying
authors.initials: SY
authors.lastname: Lee
authors.forename: Zhen
authors.initials: Z
authors.lastname: Xie
authors.forename: Zeng
authors.initials: Z
authors.lastname: Xie
authors.forename: Bastiaan J
authors.initials: BJ
authors.lastname: Braams
authors.forename: Joel M
authors.initials: JM
authors.lastname: Bowman
authors.forename: Michael A
authors.initials: MA
authors.lastname: Collins
authors.forename: Dong H
authors.initials: DH
authors.lastname: Zhang
authors.forename: Xueming
authors.initials: X
authors.lastname: Yang