THE MILLIMETER-WAVE SPECTRUM OF CYCLOPENTENE

The rotational spectra of cyclopentene in the ground and first four excited states of the ring-puckering vibration have been measured in the frequency range 8-100 GHz. A two-state analysis of the vibration-rotation interaction for the v = 0 and v = 1 states gives an energy separation between these states of 0.911731(6) cm-1. The ring-puckering vibrational dependence of the rotational constants has been analyzed in terms of a reduced vibrational Hamiltonian with kinetic energy terms including the ring-puckering dependence of the reduced mass. The vibrational dependence of the quartic centrifugal distortion constants, including a small dependence of ΔJ and δJ, has been accounted for. © 1992.