Atomic jumps in surface self-diffusion: W on W(110)

Although surface diffusion has been studied on the atomic level for decades, little is known about jump processes in self-diffusion. The diffusion of W atoms on the densely packed W(110) plane has therefore been examined, using the field ion microscope to probe contributions of jumps other than between nearest-neighbor sites. Measurements of the mean-square displacements of atoms along the x and y axes (〈001〉 and 〈110〉, respectively) and of the detailed spatial distribution of atomic displacements serve to define the nature of the jumps important in diffusion. It is shown that, in addition to nearest-neighbor and second-nearest-neighbor transitions along the close-packed 〈111〉, atoms also carry out jumps along 〈001〉 and 〈110〉, and that the contribution from these processes increases rapidly with temperature.