Multi-pressure analysis of the ν4 and 2ν2 bands of ammonia: self-broadening, self-mixing, and pressure-induced self-shifts

The present analysis improves previous measurements of self-broadening, self-shifting and self mixing of infrared ammonia in the wavenumber range 1000-1800 cm-1 at room temperature, based on spectra recorded using a high-resolution Fourier transform spectrometer Bruker IFS 120 HR. Previous studies in this spectral region catalogued numerous line-broadening, -shifting and -mixing. In the present paper, the corresponding spectroscopic parameters are obtained for 115 new lines in both 4 and 22 bands. The accuracies of self-broadening coefficients are about 3%. The mean accuracies of line-shifting and line-mixing data are estimated to be about 20% and 14%, respectively. As shown in a previous paper, the first-order Rosenkranz absorption coefficient taking into account line-mixing effects is adequate to extract with sufficient accuracy pressure-broadening as well as line-mixing and -shift parameters of self-perturbed NH3. Comparison of the results obtained with previous measurements and present theoretical calculations are given.