O₂- and air-broadening coefficients in the ν₄ band of ¹²CH₄ at room temperature

Using a diode laser spectrometer, 50 collisional broadening coefficients in the ν band of methane perturbed by oxygen have been measured at room temperature. We have analyzed ro-vibrational lines in the P- and R-branches with J values between 1 and 12 located in the spectral range between 1241.861 and 1373.201 cm. The Voigt and Rautian profiles have been used to determine the collisional half-widths. The collisional broadening coefficients are compared with those of various absorption bands. Furthermore, from these O-broadening coefficients and from the N-broadening coefficients previously measured for the same vibrational band, we have calculated air-broadening coefficients in the ν band of CH. These results based on a simple atmospheric composition are compared with a few coefficients that we have measured with dry air, and with HITRAN values.