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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]

Abstract: XPS, TPD, LEED and STM have been used to probe the interaction between sulfur dioxide and the Ni(100) and Ni(100)-p(2×2)-O surfaces. On Ni(100) at 300K SO2 disproportionates according to 2SO2 →S(a)+SO3(a)+O(a). Sulfur and sulfite occupy sites in a p(2×2) arrangement, while oxygen adsorbs into c(2×2) domains amid Ni chains of (n√2×2√2)R45°/(2√2× n√2)R45° (n =7–12) periodicity that are presumed to be due to segregation of oxygen to the subsurface. On Ni(100)-p(2×2)-O at 300K SO2(a) reacts with O(a) to form SO3(a). Sulfite adsorbs into p(2×2) islands encompassed by c(2×2)-O. TPD measurements with 18O are suggestive of a monodentate sulfite binding configuration. [Copyright &y& Elsevier]