A simultaneous analysis of the microwave, submillimeterwave, and infrared transitions between the ground and ν2 inversion-rotation levels of 15NH 3

The submillimeterwave spectra of the pure inversion and inversion-rotation transitions in the ν₂ excited state (79 transitons) and the diode laser spectra of the ν₂ band (83 transitions) of ¹⁵NH ₃ have been measured. A simultaneous least squares analysis has been carried out of these data together with previously published wavenumbers of the pure inversion transitions and inversion-rotation transitions in the ground state measured by the microwave and Fourier spectroscopy, and the ν₂ band transition frequencies obtained by the infrared-microwave two-photon technique. A theory of the ∆k = ±3 n interactions in the ground and ν₂ excited states of ammonia (Š. Urban, V. Špirko, D. Papoušek, J. Kauppinen, S. P. Belov, L. I. Gershtein, and A. F. Krupnov, J. Mol. Spectrosc.88, 274-282 (1981)) has been used in the analysis. The "smoothed" values of the ν₂ band wavenumbers can be used for calibration purposes with better than 1 × 10 ^-3 cm ^-1 precision.