Temperature dependence of N₂- and O₂-broadening coefficients in the ν₄ band of ¹³CH₄

Using a tunable diode laser spectrometer and an home made cooling cell, the N- and O-broadening coefficients of CH were measured at room and low temperatures in the ν band near 1300cm . Fifteen transitions were studied for the CH diluted in the nitrogen at room temperature and 11 of them were also studied at 273.0 K, 248.0 K, 223.0 K, 198.0 K and 173.0 K. Twenty-four lines were considered at room temperature for the gas-mixture CH + O and 10 of them were analyzed at low temperatures (273.0 K, 223.0 K and 173.0 K). The measurements at low temperatures allowed the determination of the temperature dependence parameter of the collisional broadening coefficients. The line parameters were obtained by fitting, to the experimental profile, the Voigt lineshape and the Rautian and Sobel'man model taking into account the collisional narrowing. In addition, air-broadening coefficients were calculated in the ν band of CH for 10 transitions studied jointly for the mixtures CH + N and CH + O. We compare, in this paper, the collisional broadening coefficients determined at room temperature with previous studies on the ν and ν bands of CH. The results are also confronted with N- and O-broadening coefficients determined in the ν band of CH. The air-broadening coefficients, based on a simple atmospheric composition, are compared with HITRAN values.