High-Resolution, Rotationally Resolved Electronic Spectroscopy of the MgNC Radical.

High-resolution, rotationally resolved, laser-induced fluorescence (LIF) spectra for the origin band, as well as several transitions involving vibrationally excited levels of the Ã2Pi <-- &Xtilde2Sigma+ electronic transition of the MgNC radical, have been recorded using the output of a pulse-amplified Ti:Sapphire ring laser. The MgNC radical was generated in a supersonic free jet expansion by simultaneous laser ablation of a magnesium rod and photolysis of acetonitrile (CH3CN). Rotational analysis yielded molecular constants for both the ground and excited states of the studied vibronic transitions. The molecular constants for the vibrationless state of the &Xtilde state are in excellent agreement with previous microwave studies of MgNC. Since the à electronic state of MgNC is a linear 2Pi state, the bending vibronic level structure is subject to both Renner-Teller and spin-orbit coupling. Suggested vibronic assignments of the observed transitions, made considering both these interactions and with the aid of the rotational analysis, are discussed. Copyright 1999 Academic Press.