Tsuda Yasutaka, Gueriba Jessiel Siaron, Ueta Hirokazu, Diño Wilson Agerico, Kurahashi Mitsunori, Okada Michio
Department of Chemistry, Osaka University, Toyonaka, Osaka 560-0043, Japan.
Materials Sciences Research Center, Japan Atomic Energy Agency, Sayo-gun, Hyogo 679-5148, Japan.
JACS Au. 2022 Jul 21;2(8):1839-1847. doi: 10.1021/jacsau.2c00156. eCollection 2022 Aug 22.
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 O chemisorption on Cu(110) and CuAu(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 O.
反应物的取向和运动在反应中起着重要作用。所涉及的微小转动激发使反应物易于受到动力学操控，这使得实验与理论之间的直接比较颇具挑战性。利用空间量子化分子束，我们直接探测了O在Cu(110)和CuAu(110)上化学吸附的（极向和方位角）取向依赖性。我们在两个表面上都观察到了极向和方位角各向异性。当O - O键轴平行（相对于垂直）于表面时，化学吸附进行得较为顺利；当O - O键轴沿[001]（相对于沿[1̅10]）时，化学吸附也进行得较为顺利。Au的存在阻碍了表面的进一步氧化，引入了更高的化学吸附活化能垒，并使得方位角各向异性几乎可以忽略不计。Au的存在还阻止了O的类似车轮状的转动。
