Rotational spectrum, dipole moment, and ring-puckering potential of cyclobutane-1,1- d2
Abstract
The microwave spectrum of cyclobutane-1,1- d2 has been measured over 12-40 GHz with a pulsed Fourier transform spectrometer. Rotational transitions up to J = 40 have been assigned. Some assignments have been checked by microwave-microwave double resonance with continuous pump radiation. Transitions with J > 2 showed a doubling due to the ring-puckering motion. Rotational constants and centrifugal distortion constants have been fitted with the help of a coupled state Hamiltonian for the two puckering states simultaneously. The permanent electric dipole moment has been estimated from quantitative Stark effect measurements and from microwave-microwave double-resonance experiments. A combined analysis of the rotational constants of the d2 and d1 species and of the ring-puckering transition frequencies of the d0 and d8 species provided an improved double-minimum potential for the puckering motion. The flexible model treatment included the coupling with the CH 2 rocking motion. An energy difference of 95.2(37) MHz was found between the two lowest puckering states of cyclobutane-1,1- d2 from this analysis.
- Publication:
-
Journal of Molecular Spectroscopy
- Pub Date:
- September 1988
- DOI:
- 10.1016/0022-2852(88)90116-6
- Bibcode:
- 1988JMoSp.131..172C