Measurements and Calculation of Broadening and Shift Coefficients of Water Vapor Lines by Air and Nitrous Oxide in 2ν1 + ν2 + ν3 Band

The study of absorption by water vapor, the most powerful greenhouse gas, is important for the development of Earth’s climate models. The broadening of spectral lines become of special importance upon variations in temperature and pressure in the atmosphere. The work presents the broadening and shift coefficients of H2O lines by N2O and air pressure measured at room temperature for 11 vibrational-rotational transitions in the 2ν1 + ν2 + ν3 band, with the rotational quantum number J varied from 0 to 6. The measurements were carried out at a highly sensitive (6.5 × 10−11 cm−1) CRDS spectrometer with the apparatus function orders of magnitude narrower than the lines under study. Line broadening and shift coefficients were also calculated using the semi-classical approach modification, where a correction factor was included in the calculation scheme. The obtained parameters were compared with published data. The results can be used for refining spectroscopic information in HITRAN database.