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 configurations, dynamics, and dissociation energies of these weakly bonded complexes are obtained from their nonrigidity. The vibrational doubling (0.78 MHz) of the rotational transitions of 1,1-difluoroethylene-Ne has been useful in scaling the ab initio potential energy function calculated for the tunneling of Ne above and below the plane of 1,1-difluoroethylene. This motion is hindered 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].