通过反射吸收红外光谱和密度泛函理论研究Rh(111)上的CO吸附以及CO和O的共吸附

CO adsorption and CO and O coadsorption on Rh(111) studied by reflection absorption infrared spectroscopy and density functional theory.

作者信息

Krenn G, Bako I, Schennach R

机构信息

Institute of Solid State Physics, Graz University of Technology, Petersgasse 16/2, 8010 Graz, Austria.

出版信息

J Chem Phys. 2006 Apr 14;124(14):144703. doi: 10.1063/1.2184308.

DOI:10.1063/1.2184308

PMID:16626227

Abstract

The adsorption of carbon monoxide on Rh(111) and on oxygen modified Rh(111) was investigated using thermal desorption spectroscopy, reflection absorption infrared spectroscopy (RAIRS), and density functional theory. The results show that CO adsorbs on Rh(111) in on top sites at low coverages. With increasing coverage hollow sites and bridge sites get occupied according to the RAIRS results. A new vibrational feature at high wave numbers was found in the on top region of the CO stretching frequency. This feature can be explained by a local high density CO structure where two CO molecules are adsorbed in the ( radical3x radical3)R30 degrees structure. The coadsorption of oxygen and carbon monoxide leads to a shift of the CO stretching frequency to higher wave numbers with increasing O to CO ratio. CO adsorption on a (2x1) oxygen layer is possible and RAIRS shows that the CO adsorbs in on top and most likely in bridge sites in this case.

摘要

利用热脱附光谱、反射吸收红外光谱（RAIRS）和密度泛函理论研究了一氧化碳在Rh(111)以及氧修饰的Rh(111)上的吸附情况。结果表明，在低覆盖度下，CO以顶位吸附在Rh(111)上。根据RAIRS结果，随着覆盖度的增加，中空位和桥位被占据。在CO伸缩频率的顶位区域发现了一个高波数的新振动特征。该特征可以用局部高密度CO结构来解释，其中两个CO分子以（√3×√3）R30°结构吸附。氧和一氧化碳的共吸附导致随着O与CO比例的增加，CO伸缩频率向更高波数移动。CO有可能吸附在（2×1）氧层上，RAIRS表明在这种情况下，CO以顶位吸附，很可能也以桥位吸附。