Development of micro spectroscopic techniques and its geochemical applications.

研制了扫描近场光学显微镜(SNOM)，并将其安装在商用原子力显微镜(AFM)上。我们的SNOM系统可以同时获得样品表面的形貌图像和光致发光/拉曼信号。利用直径300 nm开口处的光纤进行光谱分析和形貌分析，使空间分辨率低于300 nm。所研究的样品是中非共和国(CAR)的多晶金刚石Carado和ZrO_2-Al_2O_3复合材料，利用SNOM对Carado的光致发光强度进行了映射，结果表明，Carado的晶界发射强度较低，Carado气孔边缘的发射强度最弱。用光学显微镜和SNOM观察到的碳纳米管的光致发光光谱包括504、575和638 nm三个尖锐的带，它们的边带不同，光致发光的颜色随着其位置的不同而变化。用光学显微镜测量的拉曼光谱表明，残余应力局部存在于样品表面之下，在本研究中观察到的最大应力值为0.72 Gpa。此外，使用高达3.5 GPA的钻石顶压室测量了575 nm波段的压力依赖关系。随着压力的增加，575 nm波段线性地向更低的波长移动，梯度为-0.57 Gpa/nm。该关系式被应用于利用SNOM估计碳酸盐的应力分布。碳纳米管表面的光致发光谱峰位置没有明显变化。这一结果表明，碳酸盐具有良好的烧结性，碳酸盐的残余应力在晶体内部局部存在。对于ZrO_2-Al_2O_3复合材料，我们观察到材料上很好的应力映射。细节很快就会公布。

Scanning Near-field Optical Microscopy(SNOM) was developed and attached to a commercial-based atomic force microscope (AFM). Our SNOM system can simultaneously obtain topographic images and photoluminescence/Raman signals from sample surface. Optical fiber with opening of 300 nm in diameter was applied for spectral and topographic analysis which enables us the spatial resolution of less than 300 nm. The studied samples were polycrystalline diamonds, carbonado, from Central African Republic (CAR) and ZrO_2-Al_2O_3 composite materials.Mapping of the photoluminescence intensity of carbonado using SNOM indicated that the emission intensity was lower at the grain boundaries ; the fringe of pores of carbonados revealed weakest intensity. Photoluminescence spectra of carbonado observed using optical microscopy and SNOM comprised three sharp bands at 504, 575 and 638 nm with their side bands and the color of photoluminescence changed according to its location. Raman spectra measured using optical microscopy revealed that the residual stress exists locally underneath the sample surface and the maximum stress value observed in this study was 0.72 GPa. Additionally, pressure dependence of the 575 nm band was measured using a diamond anvil cell up to 3.5 GPa. The 575 nm band shifted linearly to a lower wavelength with increasing pressure with a gradient of -0.57 GPa/nm. This relationship was applied to estimation of the stress distribution of carbonados using SNOM. No significant changes in peak positions of photoluminescence spectra were detected on the surface of carbonados. This result suggests that carbonado is well sintered and that the residual stress of carbonado exists locally inside the crystal.For ZrO_2-Al_2O_3 composite materials, we observed well-resolved stress mapping on the materials. The details will be published shortly.