Beam maser investigation of inelastic scattering of NH3. III. Cross sections for rotational transitions induced by CO2, N2, and H2

摘要

Cross sections for rotational transitions between various lowhyphen;lying inversion doublets of NH3in collisions with CO2, N2, and H2are measured in a doublehyphen;resonance beam maser setup. A modification of Andersonrsquo;s theory lsqb;D. B. M. Klaassen, J. J. ter Meulen, and A. Dymanus, J. Chem. Phys.77, 4972 (1982)rsqb; yields values for the cross sections that are in good agreement with the experimental results for CO2and N2. For the system NH3ndash;H2, transition probabilities are evaluated in Andersonrsquo;s theory using lsquo;lsquo;bentrsquo;rsquo; trajectories. Induction and dispersion terms up toRminus;7are considered in the longhyphen;range intermolecular potential. For the shorthyphen;range repulsive part, two empirical potentials are proposed with parameters that are fitted to the experimental results. Integral cross sections for rotational transitions calculated with these potentials are also presented.