CO2-broadening coefficients in the ν3 fundamental band of methane.

• Determination of CO 2 -broadening coefficients of lines in the ν 3 band of methane. • The half-widths were measured using a high resolution diode-laser spectrometer. • The parameters were deduced from the Voigt, Rautian-Sobel'man and Galatry profiles. In this paper, CO 2 -broadening coefficients of 11 lines in the ν 3 band of CH 4 , located between 2906 and 2959 cm−1, were measured at room temperature using an improved tunable diode-laser spectrometer. Each line was recorded for 4 different pressures, ranging from 20.15 to 60.20 mbar. The experimental determination of the CO 2 -broadening coefficients was performed by fitting a theoretical profile on the experimental line shape for each line recorded at each pressure. The Voigt, Rautian-Sobel'man and Galatry models were therefore used. The ratio between the present CO 2 -broadened results and the data available in the literature for air-broadening is investigated and compared to the ratio between N 2 - and air-broadening. The γ CO 2 / γ air presents significant differences with the ratio γ N 2 / γ air as well as a large scattering. This shows the need to make dedicated studies, both experimentally and theoretically, for CO 2 -broadening coefficients. [ABSTRACT FROM AUTHOR]