Table of Contents
International Journal of Spectroscopy
Volume 2011, Article ID 816548, 7 pages
Research Article

On the Pressure and Temperature Dependence of the Absorption Coefficient of NH3

Laboratoire de Physique Moléculaire, Ecole Supérieure des Sciences et Techniques de Tunis, 5 Avenue Taha Hussein, Tunis 1008, Tunisia

Received 27 June 2011; Accepted 24 August 2011

Academic Editor: Jean-Valère Naubron

Copyright © 2011 F. Aousgi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The effects of pressure and temperature on the absorption coefficient of ammonia (NH3) gas self-perturbed and perturbed by nitrogen (N2) gas have been measured. We varied the gas pressure from 10 to 160 Torr and the temperature from 235 to 296 K in order to study the absorption coefficient at the center and the wings of lines in the band of NH3. These measurements were made using a high resolution (0.0038 cm−1) Bruker Fourier-transform spectrometer. These spectra have been analyzed using the method of multipressure technique permitting to succeed to an evolution of the absorption coefficient with the pressure and the quantum numbers and of the NH3 molecule. The results show that the absorption coefficient varies as a quadratic function of the pressure at the center of a given line. However, it has a linear evolution in the wings of the line. Moreover, the absorption coefficients are inversely proportional to temperature in the wings when NH3 lines are broadened by N2. The retrieved values of these coefficients were used to derive the temperature dependence of N2 broadening NH3 lines. The absorption coefficients were shown to fit closely the well-known exponential law.