Transformation of iridium(110) (1×1) into (1×2) and spatial distribution of reactive carbon dioxide desorption

The spatial distribution of the desorption flux of CO2 produced on Ir(110) (1×1) and (1×2) surfaces was studied by means of angle-resolved thermal desorption and low-energy electron diffraction. The distribution is collimated along the bulk surface normal on (1×1). It is sharp in the [001] direction and sharper in the [11̄0] direction. This distribution is consistent with the model that the reactive desorption occurs on a short bridge site. On (1×2) surfaces, two-directional desorption was observed, which was collimated along the axis at the polar angle of 26 deg in both [001] and [001̄] directions. The distribution in the [11̄0] direction is collimated along the bulk surface normal. The reactive desorption was suggested to take place on a threefold hollow site on the declining terrace. The spatial distribution changed from the (1×1) type to the (1×2) type during the transformation of the surface structure. This structure change was confirmed by low-energy electron diffraction.