R. Mollaaghababa et al., MILLIMETER-WAVE SPECTRUM OF VIBRATIONALLY EXCITED CYCLOPROPENYLIDENE,C-C3H2, The Journal of chemical physics, 99(2), 1993, pp. 890-896
The millimeter-wave rotational spectrum of c-C3H2 in four vibrationall
y excited states was measured and the rotational and quartic centrifug
al distortion constants determined. Of the vibrational states observed
here, only nu3 has been previously detected in the infrared. Assignme
nt of the three new states to nu6, nu5, and nu2 was based on relative
intensities, comparison of calculated and measured inertial defects, a
nd symmetry considerations. The spectroscopic constants determined wil
l guide future infrared investigation of c-C3H2, needed for a complete
elucidation of the vibrational structure of this molecule. The experi
mental values of the vibration-rotation coupling constants will allow
comparison with theoretical calculations that have recently become fea
sible for molecules of similar size as c-C3H2. Detection in space of r
otational lines from the lowest vibrationally excited states may be po
ssible.