Fig. 1. Distribution of CO₂ absorbance near 1.96 μm at room temperature （8% CO₂ mole fraction， 120 cm absorption length）

Fig. 2. Schematic of CO₂ hyperspectral absorption measurement experiment

Fig. 3. Typical raw signals of CO₂ hyperspectral absorption at different pressures

Fig. 4. Baseline extraction of CO₂ hyperspectral absorption signal utilizing the weak absorption region

Fig. 5. Wavelength calibration of CO₂ hyperspectral absorption signal at 152 kPa

Fig. 6. Simultaneous fitting result of CO₂ hyperspectral absorption data at 152 kPa

Fig. 7. Direct baseline fitting processing result of CO₂ hyperspectral absorption data at 426 kPa

Fig. 8. Simultaneous fitting result of CO₂ hyperspectral absorption data at 426 kPa

Fig. 9. Simultaneous fitting result of CO₂ hyperspectral absorption data at 932 kPa

Fig. 10. Comparison of the theoretical and measured spectra of CO₂ absorption at different pressures

Fig. 11. P， T and X variation curves with gauge pressure retrieved from hyperspectral absorption spectra.

Fig. 12. Relative error of P， T and X retrieved from hyperspectral absorption spectra at different pressures.

Fig. 13. Comparison of wideband and narrowband inversion of CO₂ absorption spectra

Fig. 14. Curves of 1 965.98 nm spectral absorption area variation with pressure for wideband and narrowband fit