Vibrational State Resolved Dissociative Chemisorption of Methane on Ni(100)
Abstract
A three-parameter microcanonical unimolecular rate theory of gas-surface reactivity is used to investigate the dissociative chemisorption of methane impinging on a Ni(100) surface. Assuming an apparent threshold energy for dissociative chemisorption of E0 = 65 kJ/mol, dissociative sticking coefficients for individual methane vibrational states are calculated: (i) as a function of molecular translational energy to model non-equilibrium molecular beam experiments, and (ii) as a function of temperature to model thermal equilibrium mbar pressure bulb experiments. Sticking from methane in the ground vibrational state dominates the overall sticking for typical molecular beam experiments. In contrast, under the thermal equilibrium conditions most relevant to catalysis the dissociative sticking is dominated by methane in vibrationally excited states, particularly those involving excitation of the ν4 mode. The predictions of the statistical, mode-nonspecific microcanonical theory are compared to those of other dynamical theories and to recent eigenstate resolved molecular beam experiments.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MARA35008A