Knowledge Bank

The microwave spectrum of cylcopentene has been reinvestigated. In order to obtain a frequency fit of rotational transitions in the lowest pair of inversion levels a vibration-rotation coupling term has been added to the rigid-rotor Hamiltonian. This perturbation is similar to that employed by Lide in the study of $cyanamide1$. In cyclopentene this perturbation has given a value for the inversion doubling of $0.91cm-1$. Careful examination of Stark perturbation between the inversion doublets has allowed an independent measure of the doubling, indicating an upper limit of $0.95cm-1$. The determination of the potential function for the out-of-plane bend will also be discussed.