An FTIR study of the rotation of ammonia in solid nitrogen

The infrared spectra of NH₃, NH₂D, NHD₂ and ND₃ in solid nitrogen have been studied with 0.05 cm^?1 resolution. All isotopic species of ammonia rotate around their c axis. The matrix actively participates in this motion. The resulting potential barrier is six-fold, showing that the trapping site has high symmetry. The ammonia inversion, which is strongly perturbed by the nitrogen matrix, is completely inhibited by large concentrations of polar molecules.