Thermally stimulated desorption of Na+ and Cs+ ions from a NaAu alloy film grown on Au

The formation of Na⁺ and Cs⁺ ions on and their thermal desorption from the surface of a NaAu alloy film grown on metallic gold are studied. It is shown that thermionic emission from insulator-coated metallic substrates is governed by a sequence of processes, such as diffusion of Na and Cs adatoms into the film, ionization of these atoms at the insulator-metal interface, diffusion of the resulting ions toward the surface, and desorption of the ions. The effect of weak electric fields on ion diffusion and desorption is investigated.