论文标题
CO在氧化铝上的常规PDAU簇上的CO吸附的分子束研究
Molecular Beam Study of the CO Adsorption on a Regular Array of PdAu Clusters on Alumina
论文作者
论文摘要
CO在PDAU双金属簇上的吸附动力学，其中包含140 $ \ pm $ 12原子和PD原子的0％至55％之间的组合物变化，脉冲分子束法（MBR）研究了。这些簇在Ni3al（111）上的氧化铝胶片上生长，扮演模板的作用，该模板的作用提供了具有尖锐尺寸分布和均匀成分的双金属簇的六角形阵列。假设金向表面隔离，表面浓度计算出来，在表面上的0％至90％的AU原子之间变化。从CO的吸附 - 吸附动力学中，CO的寿命在各种温度下进行测量。在低覆盖范围下，绘制Arrhenius图中的CO寿命，可以获得CO的吸附能。当Au的表面浓度增加时，CO在PDAU簇上的吸附能减少。从先前的研究中，就配体和整体效应的术语讨论了吸附能的这种演变。我们发现，整体效应在观察到的CO吸附能的降低中起主要作用。
The adsorption kinetics of CO on PdAu bimetallic clusters, containing 140 $\pm$ 12 atoms and a composition varying between 0% and 55% of Pd atoms, is investigated by a pulsed molecular beam method (MBRS). The clusters are grown on a nanostructured ultrathin film of alumina on Ni3Al (111) playing the role of a template which gives a hexagonal array of bimetallic clusters having a sharp size distribution and a uniform composition. The surface concentration calculated, assuming segregation of gold to the surface, varies between 0 and 90% of Au atoms on the surface. From the adsorption-desorption kinetics of CO, the lifetime of CO is measured at various temperatures. At low coverage, plotting the CO lifetime in an Arrhenius diagram one obtains the adsorption energy of CO. When the surface concentration of Au increases, the adsorption energy of CO on the PdAu clusters decreases. This evolution of the adsorption energy is discussed, from previous studies, in term of ligand and ensemble effects. We find that the ensemble effect plays a dominant role in the observed decrease of the adsorption energy of CO.
