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利用低温扫描隧道显微镜(LT-STM)研究了酞菁铜(CuPc)分子在Bi(111)表面上的吸附和手性自组装结构。由于较弱的分子-衬底相互作用,我们发现在液氮温度(78 K)下吸附在Bi(111)表面上的单个CuPc分子围绕着分子中心发生旋转,直到遇到其他分子形成团簇为止。随着分子覆盖度的增加,CuPc分子形成了自组装分子单层。高分辨S TM图表明,非手性的CuPc分子出现了手性特征:两个相对的酞菁基团发生了弯曲。当覆盖度超过一个分子层,酞菁铜分子的吸附取向由“平躺”转变到“站立”姿态。我们认为,酞菁铜分子的手性起源是由两种因素共同导致的结果:一种是分子-衬底之间的非对称电荷转移,另一种是相邻分子间的非对称性的范德华力作用。
The adsorption and chiral self-assembly of copper phthalocyanine (CuPc) on the Bi (111) surface were investigated by cryogenic scanning tunneling microscopy (LT-STM) Due to the weak molecular-substrate interactions, we found that a single CuPc molecule adsorbed on the Bi (111) surface at liquid nitrogen temperature (78 K) rotates around the center of the molecule until it meets other molecules to form clusters . With the increase of molecular coverage, CuPc molecules formed a self-assembled molecular monolayer. High-resolution S TM images show chiral characteristics of achiral CuPc molecules: two opposite phthalocyanine groups have been bent. When the coverage is more than one molecular layer, the orientation of copper phthalocyanine molecules shifts from “lying ” to “standing ” attitude. In our opinion, the chiral origin of copper phthalocyanine molecules is the result of two factors: one is the asymmetric charge transfer between molecules and substrates and the other is the asymmetry between adjacent molecules. Force effect.