Yu Yajun, Sanchez Nancy P, Griffin Robert J, Tittel Frank K
Opt Express. 2016 May 16;24(10):10391-401. doi: 10.1364/OE.24.010391.
A sensor system based on a continuous wave, external-cavity quantum-cascade laser (CW EC-QCL) was demonstrated for simultaneous detection of atmospheric HO, HDO, NO and CH using a compact, dense pattern multi-pass gas cell with an effective path-length of 57.6 m. The EC-QCL with a mode-hop-free spectral range of 1225-1285 cm operating at ~7.8 µm was scanned covering four neighboring absorption lines, for HO at 1281.161 cm, HDO at 1281.455 cm, NO at 1281.53 cm and CH at 1281.61 cm. A first-harmonic-normalized wavelength modulation spectroscopy with second-harmonic detection (WMS-2f/1f) strategy was employed for data processing. An Allan-Werle deviation analysis indicated that minimum detection limits of 1.77 ppmv for HO, 3.92 ppbv for HDO, 1.43 ppbv for NO, and 2.2 ppbv for CH were achieved with integration times of 50-s, 50-s, 100-s and 129-s, respectively. Experimental measurements of ambient air are also reported.
展示了一种基于连续波光外腔量子级联激光器（CW EC-QCL）的传感器系统，该系统使用有效光程为57.6 m的紧凑型密集图案多程气室同时检测大气中的HO、HDO、NO和CH。扫描了工作在~7.8 µm、无模式跳变光谱范围为1225 - 1285 cm⁻¹的EC-QCL，覆盖四个相邻吸收线，分别是1281.161 cm处的HO、1281.455 cm处的HDO、1281.53 cm处的NO和1281.61 cm处的CH。采用具有二次谐波检测的一次谐波归一化波长调制光谱（WMS-2f/1f）策略进行数据处理。Allan-Werle偏差分析表明，HO、HDO、NO和CH的最低检测限分别为1.77 ppmv、3.92 ppbv、1.43 ppbv和2.2 ppbv，积分时间分别为50 s、50 s、100 s和129 s。还报告了对环境空气的实验测量结果。
