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The effect of sulfur on alkoxide formation and decomposition on the Ni(100) surface is investigated with scanning tunneling microscopy (STM) and low energy electron diffraction (LEED). The STM images reveal details of the p(2 X 2) and c(2 x 2) sulfur-covered.

An investigation on the adsorption of formate and acetate on the Ni(110) surface is presented with STM, LEED, TPRS, and XPS. The study concluded that the added Ni in the formate structure facilities the decomposition of formate into CO2, H2, and scattered Ni(sub x) nuclei, which act as sites for further formate decomposition.

On the Ag(111)-p(4×4)-O surface SO2(g) reacts with oxygen according to SO2(g)+O(a)→SO3(a). Sulfite forms in a (2[Square_Root]3×2[Square_Root]3)R30° structure. The restructuring of the surface atoms during sulfite formation is indicative of the deconstruction of the p(4×4)-O structure. Heating the sulfite-covered surface to 700 K affects the disproportionation of SO3 to SO4 in a (4[Square_Root]3×[Square_Root]3)R30° structure accompanied by the desorption of SO2(g) and smoothing of the surface. Continued heating beyond 700 K affects the complete decomposition of sulfate to SO2(g) and O2(g). [ABSTRACT FROM AUTHOR]

On Cu(110)-p(2×1)-O at 300 K SO[sub 2](g) reacts stoichiometrically with O(a) to form a surface covered with both c(4×2)-SO[sub 3] and p(2×2)-SO[sub 3] structures. With heating SO[sub 2](g) evolves from the surface in distinct reaction-limited states at 384 K, 425 K, and 470 K, and the surface reverts to its initially oxidized state. On Cu(110), SO[sub 2](g) adsorbs molecularly below 300 K; upon annealing to 300 K, the sulfur dioxide disproportionates according to 3SO[sub 2](a)→S(a)+2SO[sub 3](a) with concomitant desorption of excess SO[sub 2](a). The surface formed in this manner exhibits large c(2×2)-S domains which encompass scattered c(4×2)-SO[sub 3] and p(2×2)-SO[sub 3] structures in a 1:2 coverage ratio. After being annealed to 400 K, the surface exhibits large p(2×2)-SO[sub 3] domains surrounding smaller c(4×2)-SO[sub 3] and c(2×2)-S islands. Continued heating past 400 K results in decomposition of sulfite according to SO[sub 3](a)→SO[sub 2](g)+O(a), evolving sulfur dioxide at 470 K and leaving the surface covered with atomic sulfur and oxygen. Real-time STM images show the mobility of oxygen at island boundaries and the mobility of sulfite amid the p(2×1)-O structures. STM measurements suggest that the sulfite occupy four-fold hollow sites. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The scanning tunneling microscopy (STM) and temperature-programmed desorption (TPD) are combined to show changes to the Ni(110) surface structure upon formation of the (beta3) state of hydrogen which is mediated by CO. The results indicate that CO induces the segregation of a fraction of the hydrogen from the Ni-H overlayer into the subsurface and the remainder evolves into the gas phase.

Abstract: The adsorption and reaction of nitrogen dioxide on the Ag(111)-p(4×4)-O surface has been investigated with RAIRS, TPRS and STM. At 300K NO2 initially reacts with the oxygen overlayer to form nitrate in p(3×3) and p(4×4) structures, which convert to a new p(3×3) at saturation coverage. Surface pitting during nitrate adsorption is suggestive of the incorporation of silver atoms into the NO3 structure. With heating NO3 decomposes into NO2 and O at 396K and 497K, and oxygen desorbs at 578K. [Copyright &y& Elsevier]

The effects of hydrogen adsorption and desorption on the structure and morphology of Ni(1 1 0) have been investigated with STM over a wide range of temperatures and pressures. The adsorption of hydrogen at moderate coverage results in the formation of –Ni–H– strings and missing rows of Ni atoms oriented along the [1 1¯ 0], in agreement with previous work. At low hydrogen coverage only missing rows of Ni atoms are observed; no added rows are seen, suggestive of unresolved, mobile Nix–Hy, precursors to the –Ni–H– chains. The appearance and accumulation of the added –Ni–H strings is concomitant with the sharp, nearly vertical rise in work function reported by others, suggesting that the formation of the added row, Ni–H overlayer is due to the two-dimensional condensation of isolated –Ni–H– moieties at a critical pressure dictated by the surface temperature. During H2(g) desorption, the Ni liberated from the Ni–H overlayer fills the Ni missing rows, migrates along the [1 1¯ 0] to [0 0 1] steps or agglomerates into anisotropic islands of monoatomic step height (i.e. anisotropic 2D crystallization). The islands coalesce in time to yield isotropic structures which serve as sources of Ni for further Ni–H adsorption. [Copyright &y& Elsevier]