Development of micro spectroscopic techniques and its geochemical applications.

扫描近场光学显微镜（SNOM）被开发并连接到商用原子力显微镜（AFM）上。我们的SNOM系统可以同时获得样品表面的地形图像和光致发光/拉曼信号。采用孔径为300 nm的光纤进行光谱和地形分析，使空间分辨率小于300 nm。研究的样品为中非共和国（CAR）的多晶金刚石、碳酸盐和ZrO_2-Al_2O_3复合材料。利用SNOM对碳酸盐岩的光致发光强度进行了测绘，结果表明，碳酸盐岩在晶界处的发光强度较低；黑岩孔隙边缘的强度最弱。利用光学显微镜和SNOM观察到的carbonado的光致发光光谱在504、575和638 nm处有三个尖锐的边带，光致发光的颜色随其位置的变化而变化。利用光学显微镜测量的拉曼光谱显示，残余应力在样品表面下局部存在，本研究观察到的最大应力值为0.72 GPa。此外，575 nm波段的压力依赖性使用高达3.5 GPa的金刚石砧细胞进行测量。随着压力的增加，575 nm波段以-0.57 GPa/nm的梯度线性向更低的波长移动。将这种关系应用于用SNOM估计黑金刚石的应力分布。黑金刚石表面的光致发光光谱峰位无明显变化。这表明炭黑石烧结良好，炭黑石残余应力局部存在于晶体内部。对于ZrO_2-Al_2O_3复合材料，我们观察到材料上有很好的应力映射。详情将于稍后公布。

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.