Thermally assisted tunneling: CH4 dissociation on Pt(111)

The mechanism for the dissociation of CH4 at metal surfaces has been and is still controversial. In large part, this is because many of the experimental data suggest a direct tunneling mechanism, which is not obviously compatible with an observed strong dependence on the surface temperature. We propose here that a new phenomenon, thermally assisted tunneling, caused by a coupling of the tunnel barrier to the lattice, resolves this controversy. Explicit calculations using a simplified model for this process agree qualitatively with a wide range of experimental data for CH4 dissociation on Pt(111). © 1991 The American Physical Society.