Reaction of formaldehyde cation with molecular hydrogen: Effects of collision energy and H2CO+ vibrations.

The effects on the title reaction of collision energy (Ecol) and five H2CO+ vibrational modes have been studied over a center-of-mass Ecol range from 0.1 to 2.3 eV. Electronic structure and Rice–Ramsperger–Kassel–Marcus calculations were used to examine properties of various complexes and transition states that might be important. Only the hydrogen abstraction (HA) product channel is observed, and despite being exoergic, HA has an appearance energy of ∼0.4 eV, consistent with a transition state found in the electronic structure calculations. A precursor complex-mediated mechanism might possibly be involved at very low Ecol, but the dominant mechanism is direct over the entire Ecol range. The magnitude of the HA cross section is strongly, and mode specifically affected by H2CO+ vibrational excitation, however, vibrational energy has no effect on the appearance energy. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]