Study of the mesoscopic nano-structures by using the scanning near-field Raman spectroscopy

凝聚态物质大多具有层次化结构，特别是在结构相变过程中。微观原子排列形成了中间范围的介观结构。此外，较高的结构出现在介观结构中。因此，有必要研究纳米尺度区域出现的介观结构，以了解凝聚物质的物理性质。为了观察介观结构中的纳米拉曼散射光谱，将扫描原子力显微镜和微拉曼散射光谱相结合，研制了一种新型的扫描近场拉曼光谱系统；对于小于光波长的纳米尺度区域的观察，采用了微孔硅悬臂梁作为照明纳米尺度和散射光的纳米探测器。我们申请了这项技术的专利。为了获得更好的性能，利用选定的光学元件如透镜、密勒、滤光片等对光谱系统进行了改造，由于介观结构在其特征温度下出现，因此样品的温度应控制在较大的范围内。为此，我们研制了可安装在扫描近场拉曼光谱仪中的温控样品台。样品台的性能要求高：温度稳定性高，窗口光学损耗低，包括悬臂梁的压电式扫描系统，消除真空泵产生的振动等。利用本研究开发的系统成功地观测了近场拉曼光谱。在下一阶段，我们将攻击介观结构中的现象。

Most of the condensed matters have the hierarchical structures especially in the structural phase transition. The microscopic atomic arrangements form the mesoscopic structures in the intermediate range. In addition, the higher structures appear from the mesoscopic structures. Therefore, it is necessary to study the mesoscopic structures appeared in the nano-scale region in order to understand the physical property of the condensed mater. To observe the nano-Raman scattering spectra in the mesoscopic structure, a new type of scanning near-field Raman spectroscopic system has been developed by combing scanning atomic force microscopy with micro-Raman scattering spectroscopy.For the observation from the nano-scale region which is smaller than the wavelength of the light, a silicon cantilever with the minute aperture was used both as the illumination nano-scale and the nano-detector of scattered light. We applied for a patent about this technique. To get better performance, the spectroscopic system bas been reconstituted by using the selected optical components such as the lens, miller, filter and so on.Because the mesoscopic structure emerges at its characteristic temperature, the temperature of the sample should be controlled in the wide range. Thus, we have developed the temperature controlled sample-stage which can set in the scanning near-field Raman spectrometer. The sample-stage was required high performance: high temperature stability, low optical loss at the window, including the piezo-scanning system of the cantilever, removing the vibration produced by the vacuum pump and so on.The near-field Raman scattering spectra were successfully observed by using the system developed in the present study. In the next phase, we will attack the phenomena in the mesoscopic structure.