Hyperfine Structure of Rotation-Inversion Levels in the Excited nu2 State of Ammonia.

Hyperfine structures of the rotation-inversion transitions with J = 3 <-- 2, s <-- a, and K = 0, 1, 2, and with J = 0 <-- 1, a <-- s, and K = 0 in the excited nu2 vibrational state have been resolved and measured by sub-Doppler saturation spectroscopy using the Cologne terahertz spectrometer with an accuracy of about 1 kHz. The line frequencies of the hyperfine structures of the rotation inversion transitions (at 466, 769, 742, and 763 GHz) have been simultaneously analyzed with the previously published J = 2 <-- 1, s <-- a, K = 1, nu2 transition in terms of effective nuclear quadrupole and spin-rotation parameters. The corresponding pure rotation-inversion frequencies, deperturbed from the hyperfine effects, have also been derived. Copyright 1998 Academic Press.