Adsorption and reaction of sulfur oxide with Cu(110) and Cu(I110)-p(2X1)-O

摘要

On Cu(110)-p(2X1)-O at 300 K SO_2(g) reacts stoichiometrically with O(a) to form a surface covered with both c(4X2)-SO_3 structures. With heating SO_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_2(g) adsorbs molecularly below 300 K; upon annealing to 300 K, the sulfur dioxide disproportionates according to 3SO_2(a) -> 2SO_3 (a) with concomitant desorption of excess SO_2 (a). The surface formed in this manner exhibits large c(2X2)-S domains which encompass scattered c(4X2)-SO_3 and p(2X2）-SO_3 structures in a 1:2 coverage ratio. After being annealed to 400 K, the surface exhibits large p(2X2)-SO_3 domains surrounding smaller c(4X2)-SO_3 and c(2X2)-S islands. Contained heating past 400 K results in decomposition of sulfite according to SO_3(a)->SO_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(2X1)-O structures. STM measurements suggest that the sulfide occupy four-fold hollow sites.