W2C(0001) 表面上 CO 和 O2 的吸附。

Adsorption of CO and O2 on W2C(0001).

机构信息

National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.

出版信息

J Chem Phys. 2011 Oct 14;135(14):144704. doi: 10.1063/1.3650246.

PMID:22010728

Abstract

CO, O(2), and H(2) adsorption on a clean W(2)C(0001)√13×√13 R ± 13.9° reconstructed surface at room temperature (RT) were investigated using high-resolution electron energy loss spectroscopy (HREELS). The W(2)C(0001) adsorbs CO molecularly and adsorbs O(2) dissociatively, but does not adsorb H(2) at RT. In the CO adsorption system, two C-O stretching (antisymmetric CCO stretching) modes were found at 242.3 meV (1954 cm(-1)) and at 253.0 meV (2041 cm(-1)). The low-frequency site is occupied at first with subsequent conversion to the high-frequency site with increasing coverage. Additionally, a small peak was apparent at 104.5 meV (843 cm(-1)), and a middle peak at 50-51 meV (400-410 cm(-1)), which are assignable to a symmetric stretching mode and a hindered translational mode, respectively, of a CCO (ketenylidene) species. These observations are consistent with the CO adsorption model on top of the surface carbon. For oxygen adsorption, two adsorption states were found at 65.2-68.1 meV (526-549 cm(-1)) and 73.6 meV (594 cm(-1)): typical frequencies to oxygen adsorption on metal surfaces. Results suggest that atomic oxygen adsorption occurred on a threefold hollow site of the second W layer.

摘要

在室温下（RT），使用高分辨率电子能量损失光谱（HREELS）研究了清洁 W(2)C(0001)√13×√13 R ± 13.9°重构表面上的 CO、O(2)和 H(2)吸附。W(2)C(0001)分子吸附 CO，解离吸附 O(2)，但在 RT 下不吸附 H(2)。在 CO 吸附体系中，发现两个 C-O 伸缩（反对称 CCO 伸缩）模式，分别位于 242.3 meV（1954 cm(-1)) 和 253.0 meV（2041 cm(-1))。低频位首先被占据，随着覆盖率的增加，随后转化为高频位。此外，在 104.5 meV（843 cm(-1)) 处出现一个小峰，在 50-51 meV（400-410 cm(-1)) 处出现一个中峰，分别可归因于 CCO（烯酮亚基）物种的对称伸缩模式和受阻平移模式。这些观察结果与表面碳上的 CO 吸附模型一致。对于氧吸附，发现两种吸附态，分别位于 65.2-68.1 meV（526-549 cm(-1)) 和 73.6 meV（594 cm(-1))：这是金属表面氧吸附的典型频率。结果表明，原子氧吸附发生在第二层 W 的三重空穴位上。