Abstract Spontaneous Raman spectroscopy was used to measure changes in the ratio of water vapor to molecular nitrogen gas in laboratory air sample with relative uncertainty of 5 × 10−4 during 100 s observations. Experimental data were collected during 100 s-runs in order to obtain sufficient signal-to-noise ratios. Estimated detection limit of water vapor at signal-to-noise ratio equal to 1 was determined to be equal to 1.4 × 1013 molecules per cm3, which is equivalent to molar concentration of 7.4 × 10−7 at Standard Temperature and Pressure (STP). The achieved sensitivities make our Raman spectrometer suitable for noninvasive, rapid monitoring of gaseous species with very broad applications, for example in natural gas pipe-lines. An inexpensive, 70 mW power, multi-mode, diode-pumped solid-state laser operating near 532 nm served as an excitation source. The high sensitivity was achieved using a multi-pass cell built out of high reflectivity concave mirrors.

中文翻译：

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用于现场测定天然气管道中 H 2 O 的拉曼光谱仪

摘要 自发拉曼光谱用于测量实验室空气样品中水蒸气与分子氮气之比的变化，相对不确定度为 5 × 10−4 在 100 s 观测期间。在 100 秒运行期间收集实验数据以获得足够的信噪比。在信噪比等于 1 时，水蒸气的估计检测限被确定为等于 1.4 × 1013 个分子/cm3，这相当于在标准温度和压力 (STP) 下的摩尔浓度为 7.4 × 10−7。所达到的灵敏度使我们的拉曼光谱仪适用于气体种类的无创、快速监测，应用非常广泛，例如在天然气管道中。一种廉价的 70 mW 功率、多模、工作在 532 nm 附近的二极管泵浦固态激光器用作激发源。使用由高反射率凹面镜构建的多通道池实现了高灵敏度。