论文部分内容阅读
利用长链烷烃取代基与石墨表面的较强相互作用,可以获得烷基取代的有机小分子(酞菁、卟啉、碱基)的高分辨STM图像。理论分析表明,这些分子的吸附稳定性来源于长链烷基与石墨间较强的范德华相互作用,以及长链烷烃链间的二维结晶能。分子在表面的吸附组装结构受到分子与基底间、吸附分子间,以及溶剂与分子间作用的共同影响。对于长链烷基取代的碱基分子在石墨表面的组装结构中,分子的排列方式不仅受到烷基链与石墨间较强的取向匹配的作用,碱基分子间形成的多个氢键以及芳环离域π键的作用也会影响分子的排列方式,并且是造成烷基取代碱基分子组装结构多样性的原因。扫描隧道谱研究表明,硫醇在Au表面的自组装分子膜对电流的整流作用,来自于分子中巯基与Au表面形成的双电层,而不对称取代的NtBuPc分子在石墨表面的LB膜的电流整流行为,来源于分子内部的不对称电子结构
High-resolution STM images of alkyl-substituted organic small molecules (phthalocyanines, porphyrins, bases) can be obtained by utilizing the strong interaction between the long-chain alkane substituents and the graphite surface. Theoretical analysis shows that the adsorption stability of these molecules comes from the strong van der Waals interactions between long-chain alkyl groups and graphite, and the two-dimensional crystallization energy between long-chain alkane chains. The adsorption and assembly structure of molecules on the surface is affected by the interaction between molecules and substrates, between adsorbed molecules, and between solvents and molecules. In the assembled structure of long-chain alkyl-substituted base molecules on the graphite surface, the arrangement of molecules is not only affected by the strong orientation matching between the alkyl chain and the graphite, but also by the multiple hydrogen bonds formed between the base molecules and the aromatic The role of the ring π-bond delocalization also affects the molecular arrangement and is responsible for the diversity of the structure of the alkyl-substituted base molecules. Scanning tunneling spectroscopy results show that the rectifying effect of the self-assembled molecular film of thiol on the Au surface is due to the formation of an electric double layer between the mercapto and Au surfaces in the molecule, while asymmetric substitution of the NtBuPc molecule on the LB film on the graphite surface Current rectification behavior, derived from the asymmetric electronic structure within the molecule