温室气体及碳同位素比值傅里叶变换红外光谱分析的温度依赖关系研究

为了研究温度变化对温室气体及碳同位素比值光谱定量分析的影响,首先从理论上分析得出温室气体浓度及13CO2值的定量反演主要取决于吸收系数,并研究了吸收系数的计算方法.其次结合HITRAN数据库,研究了温度对线强、展宽以及吸收系数的影响规律,结果表明:压强为1 atm(1 atm=1.013105 Pa)恒定条件下,温度变化时,吸收系数受线强变化的影响强于受展宽变化的影响.最后通过实验验证了温室气体和碳同位素比值傅里叶变换红外光谱(FTIR)反演的温度依赖关系,其中碳同位素比值受温度变化影响幅度最大,单位温度变化对13CO2值的影响为14.37.文中结果为高精度温室气体及碳同位素比值红外光谱监测装置中的温度监控系统设计提供了理论依据.

Study on temperature dependence of the greenhouse gases and carbon isotope ratio spectral analysis

To study the influence of temperature change on the spectrum quantitative analysis of greenhouse gases and carbon isotope ratio,at first, the view that the quantitative analysis of greenhouse gases and 13CO2 value was mainly determined by the absorption coefficient was analyzed theoretically, and the calculation method of the absorption coefficient was also studied. Then referring to the HITRAN database, the temperature dependence of line intensity, FWHM and absorption coefficient were studied, the results show that the effect of line intensity is stronger than the FWHM on the absorption coefficient when the pressure is constant at 1 atm while the temperature changes. At last, the temperature dependence of greenhouse gases and carbon isotope ratio quantitative analysis based on Fourier transform infrared spectroscopy(FTIR) method was confirmed through a series of experiment, and these experiments also present that the variation of carbon isotope is more serious than the greenhouse gases variation when the temperature changes, the 13CO2 value will change 14.37 while the temperature changes 1 ℃. This study is the theoretical basis for the design of the temperature monitoring and controlling system of greenhouse gases and carbon isotope ration monitoring instrument based on FTIR with high-precision.