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 radical-inert gas clusters X-CdCH3 (X = He, Ne, Ar, Kr, and Xe) are presented. The van der Waals vibrational structure is resolved in many of these spectra, which is interpreted in terms of two modes, a stretching 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, while for Ar-CdCH3 structure attributable to both nu(s)' and nu(b)' is seen. For Kr-CdCH3 only a nu(s)' progression is observed. Unusually, the nu(b)' progression in Ar-CdCH3 appears only after a certain number of quanta are present in nu(s)'. The dispersed fluorescence spectra reveal a resolved progression in nu(s)'' for the Ar and Kr complexes. A model is advanced that is consistent with the observed vibrational structure. We also present dissociation energy data and tentatively assigned symmetries to the electronic states involved and we speculate upon the geometry of the complexes.