Field and temperature dependence of the directional walk of single adsorbed W atoms on the W(110) plane

When an adsorbed atom is subjected to a driving force at a diffusion temperature, it will perform asymmetric random walks. The driving force can be produced by an applied nonuniform high electric field. We report here a measurement of the field and temperature dependences of the drifting velocity of single W atoms on the W(110) plane. The dependences are found to agree well with an earlier theoretical model. From these data, the surface-induced dipole moment and the effective polarizability of the W adatoms can also be derived; they are found to be 0.97 debye and 14.4 ${\mathrm{\AA }}^3$, respectively. These values agree within statistical errors with other existing experimental and theoretical data.