基于CRDS和WM-DAS的宽量程免标定H_(2)S体积分数的测量

Wide-range and calibration-free H_(2)S volume fraction measurement based on combination of wavelength modulation and direct absorption spectroscopy with cavity ringdown spectroscopy

结合腔衰荡光谱(CRDS)与波长调制-直接吸收光谱(WM-DAS),建立了一种宽量程、免标定的气体体积分数的检测方法,具有CRDS高信噪比及WM-DAS快速和可测量绝对体积分数的优点.基线衰荡时间(τ)可通过测量谱线中心频率处吸收率(WM-DAS)和衰荡时间(CRDS)计算得到,无需实时校准,极大提升了CRDS测量速度.室温常压下,在6336.617 cm处不同体积分数的H_(2)S测量结果表明,该方法动态测量范围可扩展到4个数量级以上,测量精度相比WM-DAS得到了提高,且检测限可在40 s内达到1×10^(9).

Combining cavity ring down spectroscopy(CRDS)and wavelength modulated direct absorption spectroscopy(WM-DAS),a wide range and calibration-free gas concentration detection method is established,which has the advantages of high signal-to-noise ratio of CRDS and fast speed and measurable absolute concentration of WM-DAS.The baseline ring down time(τ)can be calculated by measuring the absorptivity(WM-DAS)and ring down time(CRDS)at the central frequency of the spectral line,without real-time calibration,which greatly improves the speed of CRDS measurement.The measurement results of different H_(2)S concentrations at 6336.617 cmat room temperature and atmospheric pressure show that the dynamic measurement range of this method can be extended to more than 4 orders of magnitude,the measurement accuracy is improved in comparison with WM-DAS,and the detection limit can reach 1×10^(9)in 40 s.