Collisional broadening and shifting of ammonia absorption lines at 790 nm

By using a diode laser spectrometer based on a commercial heterostructure diode laser operating in "free-running" mode, line shape parameters of some ammonia ro-vibrational overtones at 790 nm have been measured at room temperature. These weak absorption lines have been detected by using the wavelength modulation spectroscopy technique with second-harmonic detection. The broadening and shifting coefficients have been obtained for ten absorption lines by fitting the collected second-harmonic absorption features and varying the pressure of different buffer gases.