Intermodulated photoacoustic method was applied to the measurement of the pressure broadening coefficients of selected rotational lines in the ν5 band of 12CH3OH by using a conventional cw CO2 laser. From Doppler-free spectra obtained in the pressure range from 0.1 to 1 Torr, self-broadening coefficients are determined for ten rotational lines that produce far infrared laser emission by optical pumping.
