Adsorption of elemental S on Ni(100) surfaces

• Published in: Surface science 1995-09, Vol.338 (1), p.77-82
• Main Authors: Papageorgopoulos, C.A., Kamaratos, M.
• Format: Article
• Language: English
• Subjects: Adsorption and desorption kinetics; evaporation and condensation; Applied sciences; Auger electron spectroscopy; Chemistry; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; General and physical chemistry; Low energy electron diffraction (LEED); Metals. Metallurgy; Nickel; Physics; Silicon; Solid-fluid interfaces; Solid-gas interface; Surface physical chemistry; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thermal desorption spectroscopy; Work function measurements
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/0039-6028(95)00489-0

We have studied the adsorption of elemental S on Ni(100) surfaces by LEED, AES, TDS and WF measurements in UHV. We compared the measurements to those of reported investigations, most of which used H 2S as sulfur source. The elemental S, at room temperature, is grown on Ni(100) in a layer by layer mode. Sulfur forms the p(2 × 2), initially, and subsequently the c(2 × 2) structure at the completion of the first S layer. The second layer is disordered. These findings are in contrast with most of the published papers which report that the S on Ni(100) saturates in the first layer, its sticking coefficient decreases drastically and it does not desorb before 1200 K. Deposition of S, at RT, increases the work function of Ni by 0.25 eV. Heating before the desorption temperature (1100 K) of S causes: (a) a rearrangement of Ni atoms with a possible diffusion of Ni from the bulk to the surface, having the tendency to interact with the S overlayer and (b) an increase of the WF change close to 0.4 eV, the value reported after the exposure of Ni(100) to H 2S and subsequent heating. The AES and WF variation are related to a recently reported difference in electronic structure between the p(2 × 2)S and c(2 × 2)S structures.