Ge Aimin, Peng Qiling, Qiao Lin, Yepuri Nageshwar R, Darwish Tamim A, Matsusaki Michiya, Akashi Mitsuru, Ye Shen
Catalysis Research Center, Hokkaido University, Sapporo 001-0021, Japan.
Phys Chem Chem Phys. 2015 Jul 21;17(27):18072-8. doi: 10.1039/c5cp02702k.
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 d35-OTS reveals that the two C-H stretching modes for α-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.
宽带相敏振动和频产生（SFG）光谱被用于研究吸附在介电固体基底上的分子的取向。使用金薄膜作为本地振荡器（LO）来产生SFG信号。为简化相位测量，使用十八烷基三氯硅烷（OTS）的自组装单分子层（SAM）作为标准样品，用于在固体/空气界面上进行相敏SFG测量的相位校正。结果表明，通过相敏SFG测量可以清楚地区分熔融石英表面上LB膜中分子的绝对取向。此外，对d35-OTS的SAM的观察表明，α-CH2基团的两种C-H伸缩模式相位相反。此外，通过使用当前的相敏SFG装置，可以区分水分子在带正电和带负电的固体/液体界面上的取向翻转。
