Recognition of individual tail groups in self-assembled monolayers
Recognition of individual tail groups in self-assembled monolayers
复制标题
自组装单层中单个尾群的识别
DOI：
--
复制
发表时间：
1995
期刊：
影响因子：
--
通讯作者：
H. Ringsdorf
中科院分区：
文献类型：
--
作者：
T. Takami;E. Delamarche;B. Michel;C. Gerber;H. Wolf;H. Ringsdorf
用高能隙阻抗扫描隧道显微镜研究了不同尾基(甲基、羟基和偶氮苯)的烷硫醇和二烷基二硫化物在Au(111)表面的自组装单分子膜。与尾基相关的地形差异允许识别这些双组分单分子层中的单独分子，并确定了地形轮廓是在单层表层产生的。在吸附或热处理过程中，单分子膜的组成不会分离，它们的堆积保持有序和致密。由不同尾基的分布产生的特征模式允许关于扩散过程和特定分子间相互作用的陈述。混合二硫化物的吸附没有显示出尾基的分离，这要么是因为二硫化物在化学吸附时保持完好，要么是因为形成的硫醇酸盐横向扩散的能垒太高。在甲基链的单层中稀释的单个偶氮苯分子适合六方晶格。小的偶氮苯团簇局部破坏了六方晶格，尽管从整体上讲，单层保持了良好的填充晶格。使用扫描隧道显微镜，我们能够准确地研究这些复杂的自组装单分子膜的结构，从而有助于更好地理解有机界面。
Self-assembled monolayers of alkanethiols and dialkyl disulfides having different tail groups (methyl, hydroxyl, and azobenzene) coadsorbed onto Au(111) were studied with high-gap-impedance scanning tunneling microscopy. Topographic differences correlated to the tail groups allowed recognition ofindividual molecules in these two-component monolayers and established that topographic contours were generated at the monolayer episurface. The constituents of the monolayer do not segregate during the adsorption or thermal treatment, and their packing remained ordered and compact. Characteristic patterns generated by the distribution of the different tail groups allow statements concerning diffusion processes and specific intermolecular interactions. Adsorption of mixed disulfides showed no separation of the tail groups, either because the disulfide remained intact upon chemisorption or because the energy barrier for lateral diffusion of the thiolates formed was too high. Individual azobenzene molecules diluted in a monolayer of methyl-terminated chains fit into the hexagonal lattice. Small clusters of azobenzenes disrupt the hexagonal lattice locally, although globally the monolayer maintains a well-packed lattice. Using scanning tunneling microscopy, we are able to investigate accurately the structure ofthese complex self-assembled monolayers and thereby contribute to a better understanding of organic interfaces.