Reactivity of Vibrationally Excited Methane on Nickel Surfaces

Published

September 1, 2001

Author(s)

L Halonen, S Bernasek, David Nesbitt

Abstract

Four-Dimensional variational calculations have been performed for modeling energy flow between CH₂ stretching vibrational energy statesas the molecule adiabatically approaches a nickel surface. The model is based on a local mode Hamiltonian for isolated CH₄ and LEPS potentialdescribing surface-molecule interactions. The results suggest the possibility of mode specific effects on chemical reactivity. Specifically, thesymmetric A₁ stretch fundamental adiabatically correlates with the localized excitation in the unique CH bond pointinc, toward the Ni surface.Conversely, the antisymmetric F₂ stretch fundamental excitation correlates with A and E vibrations in the CH₃ radical, and therefore this decreeof freedom is localized away from the reactive CH bond. Landau-Zener semiclassical analysis of non-adiabatic curve crossings predicts asignificant velocity dependence to the state specific energy flow dynamics. As excitation localized in active vs spectator bonds is expected to be more efficient in accelerating CH bond cleavage and adsorption reactivity, these results offer insight in interpreting velocity and vibrationally mediated reaction dynamics of CH₄ at nickel surfaces.

Citation

Journal of Chemical Physics

Volume

115

Issue

No. 12

Pub Type

Journals

Keywords

adsorption reactivity, CH stretch fundamentals, four-dimensional quantum behavior

Citation

Halonen, L. , Bernasek, S. and Nesbitt, D. (2001), Reactivity of Vibrationally Excited Methane on Nickel Surfaces, Journal of Chemical Physics (Accessed July 18, 2024)