Fig. 1. Line intensity of CO₂, H₂O, and O₂ in the range from 6326.2 cm^-1 to 6330.5 cm^-1 at 296 K

Fig. 2. Simulated absorption spectra of CO₂ in the range from 6326.2 cm^-1 to 6330.5 cm^-1 at 298 K and 101325 Pa

Fig. 3. A linear fitting between simulated absorption peak value and concentration

Fig. 4. Variation of simulated absorption peak value with temperature

Fig. 5. Experimental setup

Fig. 6. Reference light intensity obtained by the cubic polynomial of non-absorption area

Fig. 7. Measured absorption spectra of each concentration of CO₂ at 298 K

Fig. 8. Calibration model of absorption peak value and concentration

Fig. 9. Fitting curves between absorption peak value and temperature

Fig. 10. Comparison of absolute relative error of CO₂ concentration by two methods