Kraack H, Tamam L, Sloutskin E, Deutsch M, Ocko B M
Department of Physics, Bar-Ilan University, Ramat-Gan 52900, Israel.
Langmuir. 2007 Jul 3;23(14):7571-82. doi: 10.1021/la0701430. Epub 2007 Jun 1.
The coverage dependent phase behavior of monolayers of alkyl thiols (CH3(CH2)(n-1)SH, denoted as CnSH) on mercury was studied for chain lengths 9 <or= n <or= 22, using surface tensiometry and surface-specific X-ray scattering methods. At low coverage, a disordered single layer of surface-parallel molecules is found for all n. At high coverage, a monolayer of standing-up molecules is formed, exhibiting well-ordered phases, the structure of which is n- and coverage-dependent. The molecular chains pack in a centered rectangular unit cell, with an approximately 27 degrees tilt from the surface normal toward nearest neighbors. The strong sulfur-mercury bond induces a noncentered unit cell for the headgroups, incorporating one mercury atom per two thiol molecules. The small but significant differences in structure of these films on gold and on mercury are discussed and assigned to the different structure of the subphase: long-range-ordered crystal for gold and short-range-ordered liquid for mercury.
使用表面张力测定法和表面特异性X射线散射方法，研究了链长为9≤n≤22的烷基硫醇（CH3(CH2)(n - 1)SH，记为CnSH）在汞表面单层的覆盖度依赖性相行为。在低覆盖度下，对于所有n值，都发现了表面平行分子的无序单层。在高覆盖度下，形成了直立分子的单层，呈现出有序相，其结构与n和覆盖度有关。分子链堆积在一个中心矩形晶胞中，从表面法线向最近邻倾斜约27度。强的硫 - 汞键导致头基的非中心晶胞，每两个硫醇分子包含一个汞原子。讨论了这些在金和汞上的薄膜结构的微小但显著的差异，并将其归因于亚相的不同结构：金的长程有序晶体和汞的短程有序液体。
