Probing Copper and Copper–Gold Alloy Surfaces with Space-Quantized Oxygen Molecular Beam

• Published in: JACS Au Vol. 2; no. 8; pp. 1839 - 1847
• Main Authors: Tsuda, Yasutaka, Gueriba, Jessiel Siaron, Ueta, Hirokazu, Diño, Wilson Agerico, Kurahashi, Mitsunori, Okada, Michio
• Format: Journal Article
• Language: English
• Published: American Chemical Society 22.08.2022
• Subjects: oxidation; copper; steric effect; copper−gold alloy; metal surface
• ISSN: 2691-3704; 2691-3704
• DOI: 10.1021/jacsau.2c00156

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 [1̅10]). 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.