ELECTRONIC SPECTROSCOPY OF THE OPEN-SHELL VANDERWAALS COMPLEXES X-CDCH3 (X = HE, NE, AR, KR, AND XE)

Laser excitation and dispersed fluorescence spectra of the molecular r adical-inert gas clusters X-CdCH3 (X = He, Ne, Ar, Kr, and Xe) are pre sented. The van der Waals vibrational structure is resolved in many of these spectra, which is interpreted in terms of two modes, a stretchi ng mode (nu(s)) and a bending mode (nu(b)). In the excitation spectra of He-CdCH3 and Ne-CdCH3, a progression in only nu(b)' is observed, wh ile for Ar-CdCH3 structure attributable to both nu(s)' and nu(b)' is s een. For Kr-CdCH3 only a nu(s)' progression is observed. Unusually, th e nu(b)' progression in Ar-CdCH3 appears only after a certain number o f quanta are present in nu(s)'. The dispersed fluorescence spectra rev eal a resolved progression in nu(s)'' for the Ar and Kr complexes. A m odel is advanced that is consistent with the observed vibrational stru cture. We also present dissociation energy data and tentatively assign ed symmetries to the electronic states involved and we speculate upon the geometry of the complexes.