THE MICROWAVE FOURIER-TRANSFORM, MILLIMETER-WAVE, AND SUBMILLIMETER-WAVE ROTATIONAL SPECTRA OF ISOCYANOGEN, CNCN

The rotational spectra of isocyanogen, CNCN, and its four monosubstituted isotopomers 13CNCN, CN13CN, C15NCN, and CNC15N in natural abundance in the ground vibrational state have been investigated in the spectral region from 10 to 550 GHz. The nuclear electric quadrupole hyperfine structures of the low-J transitions of the various isotopomers and of CNCN in three excited vibrational states have been analyzed and precise nuclear quadrupole coupling constants for the two 14N nuclei have been obtained. For 12C14N12C14N the magnetic spin-rotation coupling constants could also be determined. The high-J millimeter- and submillimeter-wave transitions allowed the determination of accurate rotational and centrifugal distortion constants of all five isotopomers. From the respective moments of inertia a complete rs-structure for CNCN has been obtained: {A figure is presented}. The permanent electric dipole moment of CNCN in its ground vibrational state was determined by Stark-effect measurements to be 0.7074(52) D. © 1990.