High-resolution spectroscopy of the v₂ = 2 a ← v₂ = 1 s band of ¹⁴NH₃

Twenty-one transitions of the v₂ = 2 a ← v₂ = 1 s hot band of ¹⁴NH₃ have been observed by an infrared microwave sideband laser spectrometer with an absolute accuracy of 0.00002 cm^-1. One hundred and seventeen transitions of the band have been obtained by a Fourier transform infrared spectrometer at a resolution of 0.005 cm^-1. A weighted least-squares analysis of these data has been carried out to yield 17 molecular parameters for the v₂ = 2 a state. These parameters reproduce the experimental frequencies with a root mean square deviation of 0.000123 cm^-1. To calculate the frequencies to this accuracy it was necessary to take into account the Δ(K - l) = ±3 interaction between the v₂ = 2 a and v₄ = 1 a states.