Self-broadening coefficients in the ν₄ band of CH₄ by diode-laser spectroscopy

With a diode-laser spectrometer, we have measured self-broadening coefficients of 42 lines of the P-, Q- and R-branches in the ν fundamental band of CH at room temperature, with J values ranging between 1 and 12. For the determination of self-broadening parameters, we have fitted to the experimental lineshape two theoretical line profiles: the Voigt profile taking into account Doppler and collisional broadenings, and the hard collision model developed by Rautian and Sobel'man incorporating Dicke narrowing.