Chain-length-dependent change in the structure of self-assembled monolayers of n-alkanethiols on Au(111) probed by broad-bandwidth sum frequency generation spectroscopy
Chain-length-dependent change in the structure of self-assembled monolayers of n-alkanethiols on Au(111) probed by broad-bandwidth sum frequency generation spectroscopy
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DOI：
10.1063/1.1531098
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发表时间：
2003-01-22
影响因子：
4.4
通讯作者：
Kakiuchi, T
中科院分区：
文献类型：
--
作者：
Nishi, N;Hobara, D;Kakiuchi, T
用宽带和频产生光谱研究了正硫醇[CH_3（CH_2）（n）SH，n=3-11，13-15，17]在Au（111）表面自组装单分子膜的结构.和频振动光谱显示三个明显的CH 3振动模式的所有烷乙氧基调查，表明普遍接受的图片，即长链烷乙氧基自组装膜的烷基链具有全反式构象，甚至适用于短链自组装膜。CH 3对称振动模式与CH 3不对称振动模式的强度之比的链长依赖性清楚地显示了由于奇数和偶数n的自组装膜的甲基方向不同而产生的奇偶效应，也支持了自组装膜的烷基链具有全反式构象。振动强度与甲基主轴和表面法线之间的角度的分析表明，烷醇自组装膜的结构随着n逐渐变化。(C)2003年，美国物理学会。
The structure of the self-assembled monolayers (SAMs) of n-alkanethiols [CH3(CH2)(n)SH, n=3-11, 13-15, 17] on Au(111) has been studied using broad-bandwidth sum frequency generation spectroscopy. Sum-frequency vibrational spectra show three pronounced CH3 vibrational modes for all alkanethiol investigated, indicating that the commonly accepted picture that the alkyl chain for the long-chain alkanethiol SAMs has the all-trans conformation applies even to the short chain SAMs. The chain-length dependence of the ratio of the intensity for the CH3 symmetric vibrational mode to that for the CH3 asymmetric mode clearly shows the odd-even effect due to the difference in the direction of methyl group for SAMs with odd and even n, also supporting that the alkyl chain of SAMs has the all-trans conformation. An analysis of the vibrational intensities with respect to the angle between the main axis of the methyl group and the surface normal reveals that the structure of the alkanethiol SAMs gradually changes with n. (C) 2003 American Institute of Physics.