Superlattice structure at the surface of a monolayer of octadecanethiol self‐assembled on Au(111)
Superlattice structure at the surface of a monolayer of octadecanethiol self‐assembled on Au(111)
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Au(111)上单层十八烷硫醇自组装表面的超晶格结构
DOI：
10.1063/1.464071
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发表时间：
1993
影响因子：
4.4
通讯作者：
G. Scoles
中科院分区：
文献类型：
--
作者：
N. Camillone;C. Chidsey;Gang;G. Scoles
我们报告了在长链正烷硫醇的自组装单层表面上含有一个以上烃链的单元网格的直接证据。我们对正十八烷基乙烷在Au（111）上的单层的氦衍射测量与尺寸为8.68×10.02 A的矩形原始单元网格一致，该网格包含四个晶体学上不同的烃链。这种堆积排列也可以被描述为c（4×2）超晶格，相对于之前在金上的其他正烷基硫醇单层中观察到的晶格参数为5.01 A的基本简单六边形[（R33 × R30°）]阵列。在可测量表面衍射的温度范围（30-100 K）内未观察到温度依赖性相行为，并且循环至高达50 °C的温度不会导致衍射发生可观察到的变化。有人提出，这个较大的单元网格是一个图案化的安排的烃链围绕其分子轴的旋转的结果。这种模式化的排列必须不同于通过简单类比大块正构烷烃所预期的人字形结构。
We report direct evidence of a unit mesh containing more than one hydrocarbon chain at the surface of a self‐assembled monolayer of long‐chain n‐alkanethiols. Our helium diffraction measurements for a monolayer of n‐octadecanethiol on Au(111) are consistent with a rectangular primitive unit mesh of dimensions 8.68×10.02 A containing four crystallographically distinct hydrocarbon chains. This packing arrangement can also be described as a c(4×2) superlattice with respect to the fundamental simple hexagonal [(√3×√3)R30°] array of lattice parameter 5.01 A previously observed for monolayers of other n‐alkanethiols on gold. No temperature‐dependent phase behavior is observed in the temperature range where surface diffraction is measurable (30–100 K) and cycling up to temperatures as high as 50 °C caused no observable change in the diffraction. It is proposed that this larger unit mesh is the result of a patterned arrangement of rotations of the hydrocarbon chains about their molecular axes. This patterned arrangement must be different than the herringbone structure expected by simple analogy to bulk n‐alkanes.