Knowledge Bank

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 $\nu 2$ 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 $\nu 2$ transition J=2-1,s-a,K=1 in terms of effective nuclear quadrupole and spin-rotation parameters. In addition to those, the corresponding purely rotation-inversion frequencies deperturbed from the hyperfine effects have been derived.