SCATTERING AND RECOILING ANALYSIS OF OXYGEN-ADSORPTION SITE ON THE IR(110)-C(2X2)-O SURFACE

The oxygen adsorption site on the Ir{110}-c(2 x 2)-O surface has been studied by time-of-flight scattering and recoiling spectrometry (TOF-SARS) using 4 keV Ne+ for backscattering and Ar+ for recoiling. The oxygen site was analyzed from scans of (i) backscattering intensity vs incident angle, (ii) oxygen recoil intensity vs incident and azimuthal angle, and (iii) oxygen recoil energy vs azimuthal angle. Calibrated shadow cones and trajectory simulations were used to obtain the site coordinates. This TOF-SARS data is contrasted with that of Ni{110}-p(2 x 1)-O, in which it is well established that the adsorption site is in the long-bridge position along the <001> rows. Adsorption of oxygen in the short-bridge sites above the <11BAR0> Ir rows is the only model consistent with all of the experimental data and simulations. The O-Ir bond length is estimated to be almost-equal-to 1.8 angstrom.