Collisional broadening studies of infrared spectral lines of acetylene, ethylene and ammonia using a tunable diode laser spectrometer

The collisional broadening linewidths of acetylene, ethylene and ammonia, broadened by hydrogen and nitrogen, were measured in the 10-14µm region using a tunable diode laser spectrometer. Helium broadening measurements of ethylene were also made. The spectral lines of the ν₅ band of C₂H₂ were observed at room temperature, while the C₂H₂and NH₃ measurements were taken over a range of temperatures from 152 K to 295 K. The Lorentz half-widths were found from the observed Voigt profiles, and the collisional broadening coefficients were determined. Line intensities were also retrieved from the C₂H₂ Voigt profiles. Wing corrections were made, following the method of Fridovich, in both the C₂H₂broadening and intensity retrievals. Finally, the temperature dependence of the ethylene and ammonia broadening coefficients was determined.