High-Resolution Infrared Spectroscopy of the v₁ + v₄ Band of ¹⁴NF₃:Reductions of the Rovibrational Hamiltonian

Abstract

The high-resolution Fourier transform infrared spectrum of nitrogen trifluoride NF₃ has been studied in the v₁ + v₄ perpendicular band region around 1523 cm⁻¹. All experimental data have been refined applying various reduction forms of the effective rovibrational Hamiltonian developed for an isolated degenerate state of a symmetric top molecule. The v₁ = v₄ = 1 excited state of the ¹⁴NF₃ oblate molecule was treated with models taking into account ℓ- and k-type intravibrational resonances. Parameters up to sixth order have been accurately determined and the unitary equivalence of the derived parameter sets in different reductions was demonstrated.