[1Dp01-09] Surface Science(SS1) Physical Property

[1Dp06] Probing copper and copper-gold surfaces with space- quantized oxygen molecular beams

Yasutaka TSUDA¹, Jessiel Siaron GUERIBA², Hirokazu UETA³, *Wilson Agerico Diño², Mitsunori KURAHASHI⁴, Michio OKADA^5,6 (1. Materials Sciences Research Center, Japan Atomic Energy Agency, 2. Department of Applied Physics, Osaka University, 3. Advanced Science Research Center, Japan Atomic Energy Agency, 4. Center for Basic Research on Materials, National Institute for Materials Science, 5. Department of Chemistry, Osaka University, 6. Institute for Radiation Sciences, Osaka University)

The orientation and motion of reactants play important roles in reactions. The small rotational excitations involved render the reactants susceptible to dynamical steering, making direct comparison between experiments and theory rather challenging. Using space-quantized molecular beams, we directly probed the (polar and azimuthal) orientation dependence of O₂ chemisorption on Cu(110) and Cu₃Au(110). We observed polar and azimuthal anisotropies on both surfaces. Chemisorption proceeded rather favorably with the O−O bond axis oriented parallel (vs perpendicular) to the surface and rather favorably with the O−O bond axis oriented along [001] (vs along [-110]). The presence of Au hindered the surface from further oxidation, introducing a higher activation barrier to chemisorption and rendering an almost negligible azimuthal anisotropy. The presence of Au also prevented the cartwheel-like rotations of O₂.