Recombination of Hydrogen Atoms on the Copper Single Crystal Surfaces

Abstract

The recombination of hydrogen atoms was carried out on the plane surfaces of a single crystal of copper, and the sequence of recombination activities for the three principal crystal faces was found to be γ(110)>γ(100)>γ(111). The activation energies of this reaction were estimated by Eyring's semi-empirical method for both the Rideal and the Langmuir-Hinshel-wood mechanism. In the latter case, the correspondence of the order of calculated activation energies to the experimental order of recombination activities is good in a qualitative sense. In order to explain the anisotropy of activity by means of the Rideal mechanism which appears to be more important than the other, it is necessary to take into account the repulsion potential from metal surface acting on the reacting system. This means that the anisotropy of activity does not come from the bond energy of chemisorption but rather from the repulsive potential field near the solid surface.