自组装膜在物理、化学以及生物等领域有着广泛的应用，其宏观性能主要取决于微观结构，为了设计和开发有特定功能的自组装膜，需要从微观层次上对自组装膜界面进行表征与分析。和频振动光谱（Sum Frequency Vibrational Spectra，SFVS）因其具有界面选择性和单分子层灵敏性，能够原位、实时的检测界面，是界面特异性结构研究的有效方法之一。

  本文应用SFVS研究了Si（111）表面修饰的3-氨基丙基三乙氧基硅烷（APTES）和11-氨基十一烷基三乙氧基硅烷（AUTES）的界面结构。通过测量分析不同偏振组合下，APTES和AUTES在C-H和N-H振动波段的光谱，我们发现末端氨基排列有序性随着链长的增长而增加，AUTES比APTES膜的氨基排列更有序。对Si（111）基底SFVS信号的研究发现，Si（111）基底信号具有三重旋转对称性，且SSP和PPP信号极大值对应的方位角相差60°，经数学推导表明χeff-PPP2∝-cos3ϕ,χeff-SSP2∝cos3ϕ ，合理解释了SSP和PPP的对称性差异。APTES共振峰的三重对称性与Si（111）基底一致，而AUTES中烷基链长增加降低了与Si（111）表面的耦合，其三重对称性归因于NH₂基团有向特定晶向倾斜的趋势，与Si（111）-OTS（十八烷基三氯硅烷）的对称性一致。

  由于硅表面存在自然氧化层（SiO₂），关于分子在硅和石英晶体基底上的结构是否相同还存在争议，我们实验光谱和模拟结果均表明硅和石英的界面折射率不同导致其上分子结构不同。此外，修饰在石英晶体上的APTES在3336cm^-1和3436cm^-1处存在NH₂的对称和反对称伸缩，NH₂的取向角约27°± 5°；与APTES相比，AUTES的NH₂振动峰红移10cm^-1左右，表明链长增加，烷基链间的范德华力增强，分子的排列更有序。100℃加热1小时后，APTES在3489cm^-1处出现-Si-OH振动峰，而AUTES未出现新的振动峰，表明AUTES中未成键的-Si-OH基团较少，其组装密度更大。

  相较于强度测量，相位测量SFVS可以获得物质表面分子更丰富的信息，但在实验重复性、实验设计和界面分析等方面仍有一些关键问题没有解决。相位误差会引起光谱变化并误导界面结构分析，因此分析并准确控制误差是相位测量SFVS的关键技术。论文第五章介绍了相位测量系统及原理，模拟了水分子的相位测量过程，发现存在三种类型的水分子，与文献中的实验结果一致。最后进行了SiO₂-OTS在C-H振动波段的相位测量实验，对OTS的相位光谱进行了解析，并讨论了待测样品和参考样品位置的非一致性对相位测量精度的影响。结果发现待测样品与参考样品测量位置间2.5um的位移对应于1°的相位误差，20°相位的偏移会导致零点位置移动约6cm^-1。本实验研究结果为提高和频振动光谱相位测量的精度与准确性提供了指导，为界面分子表面态的检测与分析、及微小信号的探测提供了有效手段。

      Self-assembled membranes are widely used, including physics, chemistry, and biology, which macroscopic properties mainly depend on the microstructure. In order to design and develop self-assembled membranes with specific functions, it is necessary to characterize and analyze the interface of the self-assembled membrane at a micro level. SFVS (Sum Frequency Vibrational Spectra, SFVS) is one of the effective methods for interface-specific structure research because of its interface selectivity and monolayer sensitivity, which can detect interfaces in situ and in real time.

    In this paper, the interface structure of 3-aminopropyl triethoxysilane (APTES) and 11-aminoundecyl-triethoxysilane(AUTES) modified in Si (111) surface was studied by SFVS. By measuring and analyzing the spectra of APTES and AUTES in the C-H and N-H vibration bands in different polarization combinations, we found that the order of the amino group arrangement increases with the growth of the chain length, and the amino arrangement of AUTES is more ordered than APTES. Research on the SFVS signal of Si (111) substrate found that the Si (111) substrate has a triple rotation symmetry, and the azimuth corresponding to the maximum value of the SSP and PPP signals differs by 60°. The mathematical derivation explains the difference in symmetry between SSP and PPP. The triple symmetry of the APTES resonance peak is consistent with the Si (111) substrate, while the triple symmetry of AUTES is attributed to the tendency of the NH₂ group to tilt towards specific crystal orientation, which has the same symmetry with Si (111) -OTS (octadecyltrichlorosilane).

      Due to the silicon surface has a natural oxide layer, it is controversial whether the molecules structures on the silicon and quartz crystal are the same, our experimental spectra and simulation results show that the difference in the interface refractive index between silicon and quartz leads to different molecular structures on it. In addition, APTES has NH₂ symmetrical and antisymmetric vibrations at 3336cm^-1 and 3436cm^-1 respectively, and the NH₂ orientation angle is about 27° ± 5°. Compared with APTES, the NH₂ vibration peak of AUTES redshifts by about 10cm^-1, which shows that the chain length increases, the van der Waals force between the alkyl chains increases, and the molecules are more orderly. After heating for 1 hour at 100°C, APTES appeared -Si-OH vibration mode at 3489cm^-1, but no new vibration peak appeared in AUTES, indicating that there are fewer unbonded -Si-OH groups in AUTES, and its assembly density is more greater.

    Compared with intensity measurement, the molecular orientation of the material surface can be obtained by phase measurement SFVS, but there are still some key issues in experimental repeatability, experimental design, and interface analysis. Phase error can cause spectral changes and mislead interface structure analysis. Therefore, analyzing and accurately controlling errors is the key technique for phase measurement SFVS. We introduces the system and principle of phase measurement, simulates the water molecules phase, and finds that there are three types water molecules, which are consistent with the experimental results in chapter 5 of this article. Finally, a phase measurement experiment of SiO₂-OTS in the C-H vibration band was performed. The phase spectrum of OTS was analyzed, and the influence of the position non-uniformity between the test sample and the reference sample on the phase measurement accuracy was discussed. It was found that a 2.5um displacement between the test sample and the reference sample corresponds to 1° phase error, and a 20^o phase shift will cause the zero position to move about 6cm^-1.The results of this experimental improve the accuracy of phase measurements, and contribute to the detection and analysis of molecular surface states and the small signals.