Dynamics of dissociative methane adsorption on metals: CH4 on Pt{110}(1×2)

Publisher Website
Google Scholar
Abstract
Supersonic molecular beams have been used to study methane dissociative adsorption on Pt{110} (1×2) at incident translational energies of 20 to 700 meV, incident vibrational temperatures of 300 to 800 K and surface temperatures from 400 to 1000 K. At E t ⩽100 meV, the initial dissociative sticking probability, s 0 , rises sharply. The process is facilitated by vibrational excitation of the deformation modes and surface temperature. At E t >100 meV, an activated adsorption process becomes dominant, with an activation barrier of ∼146 meV. At E t ⩾230 meV, s 0 attains a limiting value which is strongly enhanced by excitation of the C–H stretch modes in the incident molecule. An increase in the surface temperature also enhances s 0 , at all incident translational energies. The mechanistic implications are discussed and it is concluded that the low translational energy process is a distinctive steering-assisted direct adsorption pathway.