Development of Remote Sensing Apparatus of Raman Spectroscopy for the Corrosion Layer on Metals by use of Optical Fiber

激光拉曼光谱法是原位条件下评价固体表面的一种有趣的方法。对于材料表面的光学测量，试样在光路上的位置受到很大的限制。光纤的使用拓展了光学测量的应用领域。本文研制了一种利用光纤对远离拉曼光谱仪的样品表面进行测量的拉曼光谱遥感装置。仪器：该仪器由一个小型滤光片式双单色计组成，通过两根玻璃纤维与主光谱仪和氩离子激光器光学连接。激光器发出的光通过直径为0.1mm的玻璃纤维引导到样品位置，样品发出的拉曼散射光通过小滤光片式单色仪剔除Payleigh光后，通过另一根直径为0.4mm的光纤引导到主光谱仪。光纤系统造成的光损耗使灵敏度降低约1/4 ~ 1/8。结果：该仪器可用于不同形状钢试件锈蚀的拉曼光谱测量。(1)在NaCl溶液中浸渍干燥，在大尺寸碳钢表面形成锈层。这种锈病被鉴定为- feooh。(2)氮气瓶置于含少量ClD2气体的实验室室内，瓶盖锈蚀。从铁锈的拉曼光谱中，在弹的上部检测到无定形氧化铁，在弹的下部检测到- feooh和Fe_3O_4。煤气灶盖上有锈。这顶帽子长期暴露在煤气炉的火焰中。在空气中检测到α - fe2od2和FeD2OD2，它们在500D1C左右的高温下是稳定的氧化物。(4)在名古屋郊区的阳台上放了一年半的腌鱼锈迹斑斑。探测到的宽拉曼峰属于γ -FeOOH的拉曼峰。

Introduction : The laser Raman spectroscopy is one of the interesting methods for evaluating the solid surface under the in-situ condition. For an optical measurement of material surface the position of specimen is very restricted on the light path. The use of optical fiber extends the application field of the optical measurement. In the research a remote sensing apparatus of Raman spectroscopy is developed by use of optical fibers for measuring the specimen surface far from the Raman spectrometer.Apparatus : The apparatus consists of a small filter-type double monochrometer connected with the main spectrometer and Ar ion laser optically through two glass fibers. The light from the laser is guided to the sample position by a glass fiber with 0.1mm diameter and the Raman scattering light from the sample is guided to the main spectrometer through the other fiber with 0.4mm diameter after excluding the Payleigh light with the small filter-type monochrometer. The optical loss due to the fiber system decreases the sensitivity by about 1/4 to 1/8.Result : The apparatus was used for the Raman spectroscopic measurement of rust on steel specimens with various shapes. (1) Rust layer formed on the carbon steel with large dimention by dip and drying in NaCl solution. The rust is identified beta-FeOOH. (2) Rust on the cap of the nitrogen gas bamb, which was placed in a laboratory room under atmosphere including small amount of ClD2. From the Raman spectrum of the rust an amorphous iron oxide is detected in the upper part of the bomb and beta-FeOOH and Fe_3O_4 are detected in the lower part. (3) Rust on the cap of a gas stove. The cap was exposed to flame of the gas stove for a long term. Alpha-Fe2OD2 and FeD2OD2 are detected which are stable oxides at a high temperature about 500D1C in air. (4) Rust on a pickel which was left on the balcony in the suburbs of Nagoya city for one and a alf years. Broad Raman peaks are detected which are assigned to those ofgamma -FeOOH.