A new class of photo-induced phenomena in siloxane films

The light induced atomic desorption effect, known as LIAD, is observed when ever Pyrex cells, coated with siloxane films and containing alkali atoms, a re illuminated. LIAD is a non-thermal phenomenon and it call be observed ev en with very weak light intensities. We show that the simultaneous contribu tion to the photo-emission of atoms adsorbed both at the film surface and w ithin the film must be taken into account in order to fit the experimental data. We demonstrate that both the desorption efficiency and the diffusion coefficient of the alkali atoms embedded in the dielectric film depend on t he desorbing light intensity. These features characterize a new class of ph oto-induced phenomena whose analysis gives new insights in the comprehensio n of the atom-surface interaction and of the atom-bulk diffusion and opens interesting perspectives for applications.