Mode-selective chemistry on metal surfaces: The dissociative chemisorption of CH{sub 4} on Pt(111)
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003 (United States)
A quantum approach based on an expansion in vibrationally adiabatic eigenstates is used to explore CH{sub 4} dissociation on Pt(111). Computed sticking probabilities for molecules in the ground, 1v{sub 3} and 2v{sub 3}, states are in very good agreement with the available experimental data, reproducing the variation in reactivity with collision energy and vibrational state. As was found in similar studies on Ni(100) and Ni(111), exciting the 1v{sub 1} symmetric stretch of CH{sub 4} is more effective at promoting the dissociative chemisorption of CH{sub 4} than exciting the 1v{sub 3} antisymmetric stretch. This behavior is explained in terms of symmetry, mode-softening, and nonadiabatic transitions between vibrationally adiabatic states. We find that the efficacies of the bending modes for promoting reaction are reasonably large, and similar to the 1v{sub 3} state. The vibrational efficacies for promoting reaction on Ni(111) are larger than for reaction on Pt(111), due to the larger nonadiabatic couplings. Our computed sticking probabilities are in good agreement with results from recent ab initio molecular dynamics and reactive force field studies.
- OSTI ID:
- 22657999
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 18 Vol. 144; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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