Rovibronic Spectroscopy of MgCH3 Ã2E <-- &Xtilde;2A1 Transition.

We report the laser excitation and dispersed fluorescence spectra of the Ã2E <-- &Xtilde;2A1 transition of the jet-cooled MgCH3 radical. Improvements to the experiment have allowed the observation of 6(1)0 and 2(1)0 vibronic features not previously observed. Analyses of these bands, along with the previously reported 0(0)0 spectra, yield the rotational constants and values of the Coriolis and the spin-orbit coupling constants for the radical's Ã2E state. We also are able to rather completely characterize a small, dynamic Jahn-Teller effect. The dispersed fluorescence spectrum was analyzed and all observed &Xtilde;2A1 state vibrational features were assigned. Copyright 1999 Academic Press.