Spectral intensity and lineshape measurements in the first overtone band of HF using tunable diode lasers

High-resolution absorption Lineshapes for the P(3) and P(6) transitions of the first overtone (upsilon = 2-0) band of HF at 296 K have been measured u sing a pair of distributed feedback diode lasers operating near 1.31 and 1. 34 mu m, respectively. Spectral line intensities and self-broadening parame ters were determined by fitting the measured spectra with Voigt, Galatry, a nd Rautian lineshape models. Voigt profiles fit the low-pressure (<10 Torr) spectra of the P(3) transition reasonably well due to the relatively stron g collisional broadening effect. Lineshape measurements of the P(6) transit ion (for pressures ranging from 5 to 60 Torr) show significant variation fr om the Voigt lineshape model due to velocity-changing collisions that effec tively reduce the Doppler component of the spectral Line. Lineshape models that include motional (Dicke) narrowing effects, Galatry (soft collision) a nd Rautian (hard collision) profiles yield significant improvements in the spectral lineshape fits compared with Voigt profiles. The collisional broad ening coefficient (gamma) of the P(6) transition obtained from a Voigt fit is similar to 4% lower than those found with either Galatry or Rautian prof ile fits. The measured intensities and self-broadening coefficients are com pared with values in the HITRAN database and previous measurements. (C) 199 9 Academic Press.