The roaming atom: straying from the reaction path in formaldehyde decomposition

David Townsend, Sridhar A Lahankar, Suk Kyoung Lee, Steven D Chambreau, Arthur G Suits, X Zhang, J Rheinecker, L B Harding, Joel M Bowman

Research output: Contribution to journalArticlepeer-review

528 Citations (Scopus)


We present a combined experimental and theoretical investigation of formaldehyde (H2CO) dissociation to H-2 and CO at energies just above the threshold for competing H elimination. High-resolution state-resolved imaging measurements of the CO velocity distributions reveal two dissociation pathways. The first proceeds through a well-established transition state to produce rotationally excited CO and vibrationally cold H-2. The second dissociation pathway yields rotationally cold CO in conjunction with highly vibrationally excited H-2. Quasi-classical trajectory calculations performed on a global potential energy surface for H2CO suggest that this second channel represents an intramolecular hydrogen abstraction mechanism: One hydrogen atom explores large regions of the potential energy surface before bonding with the second H atom, bypassing the saddle point entirely.

Original languageEnglish
Pages (from-to)1158-1161
Number of pages4
Issue number5699
Publication statusPublished - 12 Nov 2004


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