Spectroscopic Spectroscopic line parameters in the 4ν2 band of NH3 and line intensities in the ν1, ν3 and 2ν4 bands

In this work, self-broadening coefficients as well as self-shift coefficients have been measured for the first time in 4 nu(2) overtone of NH3 at T=295 K using a high-resolution Fourier transform spectrometer. The spectra were analyzed with nonlinear least-squares multi-pressure fitting procedure to eight spectra of pure NH3. The results are discussed as a function of the J and K rotational quantum numbers and the branches. The line intensities of this band as well as those of the nu(1) and nu(3) bands lying in the same region as the 4 nu(2) overtone were retrieved using the same spectra. These data together with those of 2 nu(4) band, subject of our previous work [1], allow us to derive the transition dipole moments squared for a total of about 760 lines which were found to exhibit strong J and K dependences. These moments were also derived for 63 lines of the Delta K = +/- 2, +/- 3 forbidden transitions of the 2 nu(+/- 2)(4) sub-band. These dependences are mainly caused by Fermi and Coriolis interactions transferring intensities between the modes forming the 3 mu m region system. The analysis of these moments allows us to derive a consistent set of line intensity parameters such as vibrational transition moments, band intensities as well as Herman-Wallis coefficients. The derived parameters are found to be in agreement with previous data. (C) 2019 Elsevier Ltd. All rights reserved.