基于2.32μm TDL的CO吸收光谱参数测量

Measurement of spectroscopic parameters of CO based on 2.32μm TDL

采用2.32μm的可调谐二极管激光器(TDL)测量了一氧化碳(CO)气体v(0→2)振动带R转动带从R(4)至R(12)9条谱线在N_(2)为背景气下的碰撞展宽系数,且与HITRAN数据库对比并给出了谱线展宽系数随转动量子数的变化关系。本文通过采用WM-DAS方法提高实验信噪比,在不同压力(1~100 kPa)下采用Voigt(VP),Rautian(RP),Galatry(GP)和Speed-dependent Voigt(SDVP)模型对实验测量吸收率进行拟合并探究各类线型不同参数随压力的变化关系。本文还以R(10)谱线为例测量了该谱线在He,N_(2)和Ar为背景气下的碰撞展宽系数和压力频移系数,并探究了Dicke收敛系数和速度依赖性系数随压力变化的非线性关系,且通过定义残差-吸收峰值比,分析了不同背景气下R(10)谱线的收敛效应。最后,本文结合该波长范围内CO谱线的吸收强度、展宽特性和抗H_(2)O分子光谱干扰能力,推荐R(6)和R(10)两条谱线用于工业现场测量CO浓度。

The N_(2)-broadening coefficients for 9 CO spectral lines from R(4)to R(12)in the v(0→2)band were measured using tunable diode laser absorption spectroscopy(TDLAS)near 2.32μm.The rotational quantum number J″-dependence of the N_(2)-broadening coefficients for the studied transitions were given by comparison with the HITRAN database.The WM-DAS method was used to improve the signal-to-noise ratio(SNR)and the Voigt(VP),Rautian(RP),Galatry(GP)and speed-dependent Voigt profile(SDVP)were used to fit the measured CO absorbance to retrieve the lineshape parameters and their pressure dependence at a pressure range from 1 to 100 kPa.The He-,N_(2)-and Ar-broadening coefficients and pressure-shift coefficients for the transition R(10)were measured and compared.The nonlinear pressure dependence of the Dicke narrowing coefficient and the speed-dependent coefficient were observed and analyzed.The residual-to-absorbance peak ratio was defined to show the narrowing effects for the R(10)transition at different perturbers.At last,the transitions R(6)and R(10)were recommended for in-situ measurements of CO concentrations.