CO 2 -broadening coefficients in the ν 4 fundamental band of methane at room temperature and application to CO 2 -rich planetary atmospheres

•First determination of the CO2-broadening of lines in the ν4 band of methane were realized.•CO2-broadening of lines in the ν4 band of methane were measured accurately.•The line parameters were measured by high resolution diode-laser spectroscopy.•The line parameters were deduced from Voigt, Rautian–Sobel’man and Galatry fits.•Impact of the line parameters to CO2-rich planetary atmospheres were addressed.