Molecular orientation of organic thin films on dielectric solid substrates: a phase-sensitive vibrational SFG study
Molecular orientation of organic thin films on dielectric solid substrates: a phase-sensitive vibrational SFG study
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DOI：
10.1039/c5cp02702k
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发表时间：
2015-01-01
影响因子：
3.3
通讯作者：
Ye, Shen
中科院分区：
文献类型：
--
作者：
Ge, Aimin;Peng, Qiling;Ye, Shen
利用宽带相敏振动和频发生（SFG）光谱来研究介电固体基底上吸附的分子的分子取向。采用金薄膜来生成 SFG 信号作为本地振荡器 (LO)。为了简化相位测量，使用十八烷基三氯硅烷 (OTS) 的自组装单层 (SAM) 作为标准样品，对固/空气界面上的相敏 SFG 测量进行相位校正。结果表明，通过相敏 SFG 测量可以清楚地区分熔融石英表面 LB 膜中分子的绝对方向。此外，对d(35)-OTS SAM的观察表明，α-CH2基团的两个C-H伸缩模式处于相反的相位。此外，通过使用当前的相敏 SFG 设置，可以区分带正电和带负电的固/液界面上水分子的方向翻转。
Broadband phase-sensitive vibrational sum frequency generation (SFG) spectroscopy was utilized to study the molecular orientation of molecules adsorbed on dielectric solid substrates. A gold thin film was employed to generate a SFG signal as a local oscillator (LO). To simplify the phase measurement, a self-assembled monolayer (SAM) of octadecyltrichlorosilane (OTS) was used as a standard sample for phase correction of the phase-sensitive SFG measurements on the solid/air interface. It was demonstrated that the absolute orientation of molecules in the LB films on a fused quartz surface can be clearly distinguished by phase-sensitive SFG measurement. In addition, the observation on the SAM of d(35)-OTS reveals that the two C-H stretching modes for alpha-CH2 group are in opposite phase. Furthermore, by using the present phase-sensitive SFG setup, the orientation flipping of water molecules on positively and negatively charged solid/liquid interface can be distinguished.