The microwave spectrum of 1-pyrazoline

Halonen, L., Friz, E., Robiette, A. G. and Mills, I. (1980) The microwave spectrum of 1-pyrazoline. Journal of Molecular Spectroscopy, 79 (2). pp. 432-445. ISSN 0022-2852 doi: 10.1016/0022-2852(80)90224-6

Abstract/Summary

The microwave spectrum of 1-pyrazoline has been observed from 18 to 40 GHz in the six lowest states of the ring-puckering vibration. It is an a-type spectrum of a near oblate asymmetric top. Each vibrational state has been fitted to a separate effective Hamiltonian, and the vibrational dependence of both the rotational constants and the quartic centrifugal distortion constants has been observed and analyzed. The v = 0 and 1 states have also been analyzed using a coupled Hamiltonian; this gives consistent results, with an improved fit to the high J data. The preferred choice of Durig et al. [J. Chem. Phys. 52, 6096 (1970)] for the ring-puckering potential is confirmed as essentially correct, but the A and B inertial axes are shown to be interchanged from those assumed by Durig et al. in their analysis of the mid-infrared spectrum.