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利用量子级联激光器(QCL)结合新型小型化光学多通吸收池高灵敏度同时测量CO和N2O痕量气体。所用激光为工作在4.3 mm附近的宽调谐、无跳模外腔量子级联激光器,激光在较短的时间内(1 s)连续波长扫描,并覆盖N2O(2203.73333 cm-1)和CO(2203.161 cm-1)两种分子的吸收谱线,从而实现对N2O和CO的同时测量。利用物理基长为12 cm的新型小型化光学多通吸收池,探测光在吸收池内来回反射243次,有效光程达到29 m。利用波长调制吸收光谱和二次谐波探测技术实现了对N2O和CO的高灵敏度探测,测量系统的最低可探测浓度极限约为2.0×10-9(N2O)和1.7×10-9(CO)。
Quantum cascade lasers (QCLs) combine the high sensitivity of the new miniaturized optical multi-pass cell for the simultaneous measurement of CO and N2O trace gases. The laser used is a wide-tuned, mode-free, external-cavity quantum cascade laser working at 4.3 mm. The laser sweeps continuously in a short period of time (1 s) and covers N2O (2203.73333 cm -1) and CO (2203.161 cm-1) two kinds of molecules absorption line, in order to achieve the simultaneous measurement of N2O and CO. Using a new miniaturized optical multi-pass cell with a base length of 12 cm, the probe light reflects back and forth 243 times in the cell with an effective optical path length of 29 m. Highly sensitive detection of N2O and CO was achieved using wavelength-modulated absorption spectroscopy and second harmonic detection, with the lowest detectable concentration limits of the measurement system being about 2.0 × 10-9 (N2O) and 1.7 × 10-9 (CO) .