Temperature dependence of air- and N2-broadening coefficients in the v3 band of 13CH4

By using a mid-infrared tunable diode laser and a home-made cooling cell, the N2- and air-broadening coefficients of 13CH4 have been measured at room and low temperatures around 3.38 μm. Four transitions are studied for the 13CH4 diluted with nitrogen and air at temperatures 296, 252, 213, and 173 K. Measurements at low temperatures allow the determination of the temperature dependent parameter of the collisional broadening coefficients. The line parameters are obtained by fitting the experimental profile to the Voigt line shape. The N2- and air-broadening coefficients increase with the drop of the temperature. The collisional broadening coefficients of N2 are always larger than those of air at the same temperature. These data support the remote sensing of the Earth and outer planet atmospheres. According to our knowledge, the line parameters are reported experimentally for the first time.