Noh Jaegeun, Kato Hiroyuki S, Kawai Maki, Hara Masahiko
Advanced Nanomaterials Laboratory, Department of Chemistry, Hanyang University, 17 Haengdang-dong, Seoungdong-gu, Seoul 133-791, Korea.
J Phys Chem B. 2006 Feb 16;110(6):2793-7. doi: 10.1021/jp055538b.
Scanning tunneling microscopy (STM) and high-resolution electron energy loss spectroscopy (HREELS) were used to examine the structural transitions and interface dynamics of octanethiol (OT) self-assembled monolayers (SAMs) caused by long-term storage or annealing at an elevated temperature. We found that the structural transitions of OT SAMs from the c(4 x 2) superlattice to the (6 x square root 3) superlattice resulting from long-term storage were caused by both the dynamic movement of the adsorbed sulfur atoms on several adsorption sites of the Au(111) surface and the change of molecular orientation in the ordered layer. Moreover, it was found that the chemical structure of the sulfur headgroups does not change from monomer to dimer by the temporal change of SAMs at room temperature. Contrary to the results of the long-term-stored SAMs, it was found that the annealing process did not modify either the interfacial or chemical structures of the sulfur headgroups or the two-dimensional c(4 x 2) domain structure. Our results will be very useful for a better understanding of the interface dynamics and stability of sulfur atoms in alkanethiol SAMs on Au(111) surfaces.
扫描隧道显微镜（STM）和高分辨率电子能量损失谱（HREELS）被用于研究长期储存或高温退火引起的辛烷硫醇（OT）自组装单分子层（SAMs）的结构转变和界面动力学。我们发现，长期储存导致OT SAMs从c(4×2)超晶格转变为(6×√3)超晶格，这是由吸附在Au(111)表面几个吸附位点上的硫原子的动态移动以及有序层中分子取向的变化共同引起的。此外，发现硫端基的化学结构在室温下不会因SAMs的时间变化而从单体变为二聚体。与长期储存的SAMs结果相反，发现退火过程并未改变硫端基的界面或化学结构以及二维c(4×2)畴结构。我们的结果对于更好地理解Au(111)表面烷硫醇SAMs中硫原子的界面动力学和稳定性将非常有用。
