Room temperature self- and H₂-broadened line parameters of carbon monoxide in the first overtone band: Theoretical and revised experimental results

Lorentz self- and H₂-broadened half-width and pressure-induced shift coefficients, line mixing coefficients as well as line center positions and intensities were obtained using a nonlinear least square fitting technique for 48 (P(24) to R(23)) ro-vibrational transitions belonging to the first overtone (2←0) band of ¹²C¹⁶O at room temperature. All spectra in the 4146 to 4332 cm⁻¹ spectral interval were fitted simultaneously employing four line shape functions: the Voigt, Speed Dependent Voigt, Rautian and Speed Dependent Rautian profiles. The collisional line mixing effect has been observed and investigated as an asymmetry in the analyzed line profiles. A semi-empirical Exponential Power Gap Law method was used to estimate the self- and H₂-broadening coefficients and the collisional line mixing parameters. Additionally, a classical approach was applied to calculate the half-width coefficients of transitions in the 2←0 band for carbon monoxide broadened by H₂ and for pure CO. The classical approach based on a simple computational method, ensures the molecular motion is correctly characterized in 3 dimensions. The calculations used vibrationally independent intermolecular interaction potentials. The variation of CO half-width coefficients with rotational quantum number J≤24 was computed and compared with measurements. The agreement between the theoretical broadening coefficients is better for pure CO rather than for the CO-H₂ system. - Highlights: • Self- and H₂-broadened line parameters for transitions in the 2←0 band of CO at 298 K are reported. • Line intensities, pressure shifts, line mixing and speed dependence parameters are presented. • Calculations of self- and H₂-broadening coefficients of CO using classical impact theory are included.