High resolution electronic spectroscopy of ZnCH3 and CdCH3

ZnCH3 and CdCH3 radicals have been prepared in a cold supersonic free jet expansion and their laser-induced-fluorescence spectrum recorded for the à 2E←X̃ 2A1 electronic transition. These spectra show well resolved rotational and spin structure, which has been completely analyzed. This analysis yields the rotational constants and the components of the spin–rotation tensors in the à and X̃ states of both radicals. The observed constants are discussed in terms of the electronic structure of the radicals. It is demonstrated that the upper F2 spin–orbit component of the à 2E state of CdCH3 is strongly perturbed by another, dissociative electronic state. This leads to some predissociation of the à 2E3/2 component and a broadening of its lines. The rotational and fine structure in this state is also quite perturbed leading to an unusual, but still interpretable spectrum.