Structural study of molocular adsorption system by use of low temperature STM/AFM and Synchrotron radiation

用扫描隧道显微镜(STM)研究了CH3CN和C5H5N分子在Si(111)7*7表面的吸附结构。分子吸附位置跨越了7*7单元的区域边界。吸附结构是由吸附分子与Si(111)7*7表面之间的偶极-偶极相互作用引起的。在负偏压下的扫描隧道显微镜图像中，观察到苯胺分子呈明亮的环状特征。结果表明，苯胺分子吸附在中心吸附原子中心，其氨基向剩余原子中心吸附。观察到Si(111)7*7表面不同位置对苯胺的反应性不同。这个。中心吸附原子位比角落吸附原子位更具活性。随着苯胺分子扫描隧道显微镜覆盖率的增加，观察到由2-8个苯胺分子组成的苯胺链。从不同样品偏压下得到的图像来看，这种苯胺链的电子结构与吸附在Si(111)7*7表面上的单个苯胺分子不同。在利用同步辐射光源的研究中，设计了光束线的制备和表面结构分析系统。可以使用的同步辐射光是1800-4000 eV的能量区，并且可以用X射线吸收精细结构(XAFS)测量从硅到钾元素的K吸收边。

The adsorption structure of CH_3CN and C_5H_5N molecules on Si (111) 7*7 surface have been studied by scanning tunneling microscopy (STM). The molecular adsorption sites are crossing the domain boundary of the 7*7 unit. The adsorption structure is caused by dipole-dipole interaction between adsorbed molecule and the Si (111) 7*7 surface. In the STM images at negative sample bias, aniline molecules were observed as bright ring-like feature. It was found that aniline molecules adsorbs on the center adatom site with its amino group oriented to the rest atom site. The difference in the reactivity of the various sites on Si (111) 7*7 surface to aniline was observed. The. center adatom site is more reactive than the corner adatom one. With increasing aniline molecular the STM coverage, the aniline chain which consists of 2-8 aniline molecules was observed. From images obtained at various sample bias, this aniline chain has different electronic structure from single aniline molecule adsorbed on the Si (111) 7*7 surface. This suggests that aniline molecules polymerize on the Si (111) 7*7 surface.In the research which used the synchrotron radiation light, the preparation for the beamline and the surface structure analysis system were designed. The synchroton radiation light which can be used is an energy area from 1800 to 4000eV, and the X-ray absorption fine structure (XAFS) measurement of K absorption edge from silicon to the potassium clement is possible.