Study of CO<sub>2</sub>-broadened coefficients of water vapor in 1.1μm band

The absorption spectral parameters of water vapor molecules are the key basic scientific data for the remote sensing detection and the planetary observation applications. Based on a narrow line-width external cavity diode laser and a long-path absorption cell, 18 absorption spectral lines of CO₂-broadened water vapor molecules in the 9332-9722cm^-1 region at room temperature were measured. To obtain the CO₂-broadened water vapor molecules coefficients, the Voigt profile and the quadratic speed-dependent Voigt profile were used to fit the absorption spectrum data. The quadratic speed-dependent Voigt profile showed better fitting ability. Compared with the air-broadened coefficients of the corresponding region from the HITRAN2020 database, the mean ratios of the CO₂-broadened coefficients of water vapor molecules and the air-broadened coefficients obtained by the two models of the line shape are 1.327 and 1.454, respectively, which verifies that the method of estimating the CO₂-broadened coefficient by the air-broadened coefficient of water vapor molecules has certain reliability. This study can provide referenced data of measured spectral parameters for the detection technology and related research of atmospheric structures of Mars and Venus in the near-infrared region.