In recent combined experimental work done by Arthur Suits' group and theoretical work done in our group clear evidence has been presented showing a second pathway for this dissociation to form the molecular products, H2 and CO. This pathway bypasses the conventional transition state and can be described as "self-reaction" of the "nearly-formed" radical products H+HCO to form the much more stable molecular products. This work was first reported in
"The roaming atom: Straying from the reaction path in formaldehyde decomposition", D. Townsend, S. A. Lahankar, S. K. Lee, S. D. Chambreau, A. G. Suits, X. Zhang, J. Rheinecker, L. B. Harding and J. M. Bowman, Science 306, 1158 (2004). pdf
Several animations of trajectories that illustrate this "self-reaction" are shown below. Note they are given descriptive titles that suggest the pathway. These are all for zero total angular momentum. Feel free to copy these; however, please be sure to identify them by the URL <http://www.chemistry.emory.edu/faculty/bowman/H2CO.htm>. (Please note that the Quicktime plugin is needed to view these.)
H-atom orbits HCO and HCO counter-rotates I