ELECTRON-IRRADIATION-INDUCED REDUCTION OF MAGNESIUM-CHLORIDE THIN-FILMS DEPOSITED ON GOLD - XPS AND ISS STUDY

The ion and electron beam stimulated desorption from MgCl2 ultra-thin films is reported. The films are prepared by gas phase deposition of MgCl2 on a polycrystalline Au foil in ultra-high vacuum conditions. The MgCl2 film, held at 330 K, is uniformly bombarded with Ar-ions or electrons of 1 keV of energy. The chemical composition of the film is monitored by XPS and ISS. The ionic film surface is terminated by Cl atoms, as shown by ISS. The ion bombardment sputters the MgCl2 film, without changing the chemical composition of the film surface. In contrast, the electron beam damages markedly the film, with the reduction of Mg2+ to the metallic state. Only 10% of the original Cl is left in the film after 30 min of electron bombardment. The ISS analysis shows that Mg atoms appear on the film surface after electron irradiation.