Quantum Dynamics of Dissociative Chemisorption of CH4 on Metal Surfaces

Gernot Füchsel
Quantum Dynamics of Dissociative Chemisorption of CH4 on Metal Surfaces

A quantum dynamical (QD) description of scattering processes of polyatomic molecules such as CH4 from metal surfaces is very challenging and tackles all current limitations of Theoretical Chemistry. These limitations concern the quantum dynamics itself as well as the preparation of an accurate high-dimensional potential energy surface (PES) that accounts for up to all 15 molecular degrees of freedom.

We are especially interested in the description of an apparently contradictory phenomenon observed for the dissociative adsorption of methane on Ni(100) and Pt(111), see figure. It is well known that this reaction is more efficient for vibrationally pre-excited methane molecules. However, not all vibrational modes of methane contribute similarly to the promotion of reaction. This indicates the presence of a "late" transition state (with an extended C-H bond) that is of a very specific structure.

The aim of our work is to select the most important molecular degrees of freedom for the reaction and to construct a high-dimensional PES. With the help of quantum dynamics we are then hoping to obtain a real-time resolved description of the process and a detailed understanding of the appearance of mode-selectivity and other phenomena that allow control of the process.

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