DOMAIN-STRUCTURE OF SELF-ASSEMBLED ALKANETHIOL MONOLAYERS ON GOLD
DOMAIN-STRUCTURE OF SELF-ASSEMBLED ALKANETHIOL MONOLAYERS ON GOLD
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DOI：
10.1021/j100010a042
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发表时间：
1995-03-09
影响因子：
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通讯作者：
FOKKINK, LGJ
中科院分区：
文献类型：
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作者：
SCHONENBERGER, C;JORRITSMA, J;FOKKINK, LGJ
使用大于或等于 300 G Omega 的超高隧道电阻 R(t)，通过扫描隧道显微镜研究了 Au(111) 上自组装的十二烷硫醇单层的位置顺序。我们研究了两种单层膜，（a）通过将金基底浸入甲醇硫醇溶液中（吸附膜），和（b）通过额外的异位热处理（退火膜）。发现分子的头基化学吸附在 Au(111) 表面的相应 root 3 x root 3 覆盖层中。吸附单层的特征可以是最近邻 (nn) 行分子的组装，其中有许多缺失的 nn 行。另一方面，退火薄膜的特点是具有 2 x 4 的超结构和锯齿形的缺失化学吸附分子行。这两种不同的结构被认为源自碳骨架取向自由度的两种不同晶格。此外，退火薄膜的缺陷结构显着减少。退火至高于或接近 100 摄氏度会导致部分分子解吸；其余分子保持位置有序并以“条纹域”模式排列。
The positional order of dodecanethiol monolayers self-assembled on Au(111) is investigated with scanning-tunneling microscopy using ultrahigh tunneling resistances R(t) greater than or equal to 300 G Omega. We have studied two kinds of monolayers prepared (a) by immersion of the Au substrate into a methanoic thiol solution (as-adsorbed films), and (b) by an additional ex situ heat treatment (annealed films). The head-group of the molecules are found to chemisorb in the commensurate root 3 x root 3 overlayer of the Au(111) surface. As-adsorbed monolayers can be characterized by an assembly of nearest-neighbor (nn) rows of molecules with many missing nn rows. Annealed films, on the other hand, are characterized by a 2 x 4 superstructure and zig-zag shaped rows of missing chemisorbed molecules. The two distinct structures are proposed to originate from two different lattices of the carbon-backbone orientational degree of freedom. Annealed films show, in addition, a considerable reduction of defect structures. Annealing to greater than or similar to 100 degrees C results in the desorption of a fraction of the molecules; the remaining molecules stay positionally ordered and are arranged in a ''striped domain'' pattern.