Rotational spectra and dynamics of the van der Waals adducts of neon and argon with 1,1-difluoroethylene

The free jet millimeter wave spectra of the complexes of Ne and Ar with 1,1 -difluoroethylene are reported. Information on the equilibrium configuratio ns, dynamics, and dissociation energies of these weakly bonded complexes ar e obtained from their nonrigidity. The vibrational doubling (0.78 MHz) of t he rotational transitions of 1,1-difluoroethylene-Ne has been useful in sca ling the ab initio potential energy function calculated for the tunneling o f Ne above and below the plane of 1,1-difluoroethylene. This motion is hind ered by a barrier of about 36 cm(-1) at the planar C-2v configuration. (C) 2000 American Institute of Physics. [S0021-9606(00)00405-0].