THE HIGH-RESOLUTION FOURIER-TRANSFORM FAR-INFRARED SPECTRUM OF CYANAMIDE, H2NCN

The far infrared (FIR) spectrum of cyanamide, H2NCN, was measured from 30 to 330 cm-1 with a Fourier transform spectrometer at a resolution of 0.0025 cm-1. A total of 621 a-type rotational transitions in the inversion states 0+ and 0- and 1816 c-type inversion-rotation transit ions between 0+ and 0- were assigned. The data were combined with transitions reported by Read et al. (J. Mol. Spectrosc.115, 316-332 (1986)) as well as with several far infrared transitions recently measured with a single sideband laser spectrometer. These were fitted with a Watson S-reduction Hamiltonian which included Coriolis coupling terms. The obtained molecular constants are consistent with those previously determined by Read et al. but less correlated and more precise. An additional 154 transitions with Ka ≥ 10 have also been assigned but arc not included in the fit. These transitions seem to be affected by interactions with low lying vibrational states and their frequency and/or wavenumber positions are no longer well described by the usual power series Hamiltonian. © 1993 Academic Press, Inc.