Kunat M, Traeger F, Silber D, Qiu H, Wang Y, van Veen A C, Wöll Ch, Kowalski P M, Meyer B, Hättig C, Marx D
Lehrstuhl für Physikalische Chemie I, Ruhr-Universität Bochum, 44780 Bochum, Germany.
J Chem Phys. 2009 Apr 14;130(14):144703. doi: 10.1063/1.3098318.
The adsorption of CO on the rutile TiO(2)(110) surface was investigated using He atom scattering (HAS), high resolution electron energy loss spectroscopy (HREELS), thermal desorption spectroscopy (TDS), and different types of ab initio electronic structure calculations. The experimental and theoretical results allow to put forward a consistent picture for this rather complicated adsorbate system. At 70 K a (2x1) adlayer with a glide symmetry plane is formed, containing two molecules per unit cell which are tilted in alternate directions by about 20 degrees relative to the surface normal. For this high density phase, the theoretical calculations reveal a substantial repulsion between CO molecules on neighboring lattice sites, in accord with the results of a detailed analysis of the experimental TDS data. The CO binding energy depends strongly on coverage and varies between 0.20 eV for the saturated monolayer and 0.36 eV for isolated molecules. The CO-CO repulsion leads to the desorption of about half of the CO molecules above 70 K and the formation of low density phases. HAS gave no indication of ordered adlayers at these lower coverages. For the internal stretching vibration of the CO molecules a value of 273 meV was determined by HREELS, in very good agreement with the theoretical calculations.
利用氦原子散射（HAS）、高分辨电子能量损失谱（HREELS）、热脱附谱（TDS）以及不同类型的从头算电子结构计算方法，研究了CO在金红石型TiO₂(110)表面的吸附情况。实验和理论结果为这个相当复杂的吸附体系提供了一个一致的描述。在70K时，形成了一个具有滑移对称面的(2x1)吸附层，每个晶胞包含两个分子，它们相对于表面法线交替倾斜约20度。对于这个高密度相，理论计算表明相邻晶格位点上的CO分子之间存在显著的排斥作用，这与对实验TDS数据的详细分析结果一致。CO的结合能强烈依赖于覆盖度，在饱和单层时为0.20eV，孤立分子时为0.36eV。CO-CO排斥作用导致在70K以上约一半的CO分子脱附，并形成低密度相。在这些较低覆盖度下，HAS没有显示出有序吸附层的迹象。通过HREELS测定，CO分子内部拉伸振动的值为273meV，与理论计算结果非常吻合。
