Photostimulated diffusion of atoms adsorbed on a solid surface

A new light-induced effect—surface photodiffusion—is found in the processes of transfer on a solid surface. The essence of the effect is that the energy of electronic excitation of an adsorbed atom is transformed into that of its motion over the surface. It is shown that, under nonuniform illumination of the surface, the adsorbed atoms are moved away from the illuminated region, with the atomic concentration at the boundary between the illuminated and dark regions exceeding the equilibrium value. The dark and photoinduced diffusion coefficients are measured, and the value of the diffusion barrier height is estimated.