Dy@C82分子在Au(111)表面依赖于覆盖度的取向研究

利用超高真空扫描隧道显微镜, 在低温(80 K)下研究了同分异构体分子Dy@C₈₂在Au(111)表面的吸附与分子取向．在低覆盖度下，Dy@C₈₂分子优先吸附于台阶边缘形成分子团簇与分子链结构．这种吸附取决于分子-衬底的相互作用，并存在多种不同的分子取向．增大分子覆盖度后，Dy@C₈₂在金表面形成二维有序密排的单层膜结构．Dy@C₈₂分子在金表面的取向倾向于其C₂长轴与金表面近乎平行．具有三种取向的分子最具优势，而同种取向的分子组成许多局限于一个个小区域内的取向有序结构畴．随着覆盖度的增加，Dy@C₈₂分子在Au(111)表面趋向于短程有序取向排列，这是由分子-衬底作用与分子间的偶极-偶极作用共同决定的．

Coverage-dependent Orientations of Dy@C82 Molecules on Au(111) Surface

The adsorption and molecular orientation of Dy@C82 isomer I on Au(111) has been investi-gated using ultrahigh-vacuum scanning tunneling microscopy at 80 K. At low coverages, the Dy@C82 molecules tend to grow along the step edges of Au(111), forming small clusters and molecular chains. Adsorption of Dy@C82 on the edges is dominated by the fullerene-substrate interaction and presents various molecular orientations. At higher coverages, the Dy@C82 is found to form ordered islands consisting of small domains of equally oriented molecules. The Dy@C82 molecules in the islands prefer the adsorption configurations with the major C2 axis being approximately parallel to the surface of the substrate. Three preferable orientations of the Dy@C82 molecules are found in a two-dimensional hexagonal close packed overlayer. These observations are attributed to the interplay of the fullerene-substrate interaction and dipole-dipole interaction between the metallofullerenes.