The roaming atom: straying from the reaction path in formaldehyde decomposition.
We present a combined experimental and theoretical investigation of formaldehyde (H2CO) dissociation to H2 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 H2. The second dissociation pathway yields rotationally cold CO in conjunction with highly vibrationally excited H2. 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.
Townsend
D
D
Department of Chemistry, Stony Brook University, Stony Brook, NY 11794, USA.
Lahankar
S A
SA
Lee
S K
SK
Chambreau
S D
SD
Suits
A G
AG
Zhang
X
X
Rheinecker
J
J
Harding
L B
LB
Bowman
J M
JM