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HF(v′ = 3) forward scattering in the F + H2 reaction: Shape resonance and slow-down mechanism
- Xingan Wang*,
- Wenrui Dong*,
- Minghui Qiu†,
- Zefeng Ren*,
- Li Che*,
- Dongxu Dai*,
- Xiuyan Wang*,
- Xueming Yang*,‡,
- Zhigang Sun*,§,
- Bina Fu*,
- Soo-Y. Lee§,
- Xin Xu¶, and
- Dong H. Zhang*,‡
- *State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China;
- †Department of Physics, Dalian Jiaotong University, Dalian 116028, Liaoning, China;
- §School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637616; and
- ¶Department of Chemistry, Xiamen University, Xiamen 361005, Fujian, China
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Edited by Richard N. Zare, Stanford University, Stanford, CA, and approved February 8, 2008 (received for review November 15, 2007)
Abstract
Crossed molecular beam experiments and accurate quantum dynamics calculations have been carried out to address the long standing and intriguing issue of the forward scattering observed in the F + H2 → HF(v′ = 3) + H reaction. Our study reveals that forward scattering in the reaction channel is not caused by Feshbach or dynamical resonances as in the F + H2 → HF(v′ = 2) + H reaction. It is caused predominantly by the slow-down mechanism over the centrifugal barrier in the exit channel, with some small contribution from the shape resonance mechanism in a very small collision energy regime slightly above the HF(v′ = 3) threshold. Our analysis also shows that forward scattering caused by dynamical resonances can very likely be accompanied by forward scattering in a different product vibrational state caused by a slow-down mechanism.
Footnotes
- ‡To whom correspondence may be addressed. E-mail: xmyang{at}dicp.ac.cn or zhangdh{at}dicp.ac.cn
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Author contributions: D.D., Xiuyan Wang, X.Y., and D.H.Z. designed research; Xingan Wang, W.D., M.Q., Z.R., L.C., D.D., Xiuyan Wang, X.Y., Z.S., B.F., S.-Y.L., X.X., and D.H.Z. performed research; Xingan Wang, W.D., M.Q., Z.R., L.C., D.D., Xiuyan Wang, X.Y., Z.S., B.F., S.-Y.L., X.X., and D.H.Z. analyzed data; and X.Y. and D.H.Z. wrote the paper.
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The authors declare no conflict of interest.
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This article is a PNAS Direct Submission.
- © 2008 by The National Academy of Sciences of the USA
