Cavity-enhanced Raman spectroscopy with optical feedback cw diode lasers for gas phase analysis and spectroscopy
Cavity-enhanced Raman spectroscopy with optical feedback cw diode lasers for gas phase analysis and spectroscopy
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DOI：
10.1039/c2an35722d
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发表时间：
2012-01-01
期刊：
影响因子：
4.2
通讯作者：
Hippler, Michael
中科院分区：
文献类型：
--
作者：
Salter, Robert;Chu, Johnny;Hippler, Michael
介绍了一种腔增强拉曼光谱（CERS）的变体，其中二极管激光辐射在635 nm处耦合到由两个高反射镜组成的外部线性光学腔中。利用光学反馈稳定，循环激光功率增加了3个数量级。强拉曼信号在正向散射几何中被采集。记录了H-2，空气，CH4和苯的气相CERS光谱，以展示分析应用和基础分子研究的潜力。在10 mW激励激光器的良好线性下，可实现ppm体积范围内（1 bar样品）的噪声等效检测限，灵敏度随激光功率和集成时间的增加而增加。该设备可以用电池供电的组件操作，因此可以非常紧凑和便携。可能的应用包括氢气水平的安全监测，同位素示踪剂研究（例如，N-14/N-15比率），观察氢的同位素（例如，放射性氚），以及同时进行多组分气体分析。CERS有潜力成为灵敏气相拉曼光谱的标准方法。
A variant of cavity-enhanced Raman spectroscopy (CERS) is introduced, in which diode laser radiation at 635 nm is coupled into an external linear optical cavity composed of two highly reflective mirrors. Using optical feedback stabilisation, build-up of circulating laser power by 3 orders of magnitude occurs. Strong Raman signals are collected in forward scattering geometry. Gas phase CERS spectra of H-2, air, CH4 and benzene are recorded to demonstrate the potential for analytical applications and fundamental molecular studies. Noise equivalent limits of detection in the ppm by volume range (1 bar sample) can be achieved with excellent linearity with a 10 mW excitation laser, with sensitivity increasing with laser power and integration time. The apparatus can be operated with battery powered components and can thus be very compact and portable. Possible applications include safety monitoring of hydrogen gas levels, isotope tracer studies (e.g., N-14/N-15 ratios), observing isotopomers of hydrogen (e.g., radioactive tritium), and simultaneous multi-component gas analysis. CERS has the potential to become a standard method for sensitive gas phase Raman spectroscopy.