Recombination of atoms at surfaces. Part 9.—Hydrogen atoms on Pd-Ag and Cu-Ni alloys

Abstract

The recombination of hydrogen atoms on palladium-silver and copper-nickel alloys has been studied over the whole composition range. The alloys were thoroughly annealed and it was found that the lattice spacings varied smoothly with composition. Electron-probe micro-analysis showed that, in all samples, the surface composition was not appreciably different from the bulk. For both systems the recombination coefficient showed a maximum value for an intermediate alloy. The activity decreased slowly towards the group 8₃ metal and more sharply towards the group 1_B metal. This behaviour could be accounted for on the basis of the band theory of the electronic structure of these alloys. It was also possible to account for differences between the two systems.