Pulsed-laser spectroscopy of the highly excited [formula omitted] and [formula omitted] states of MgH.

• MgH was made in a laser-ablation molecular jet. • Highly excited states were studied with single UV photons and two-photon techniques. • First observation of C 2 Π state with laser techniques. • 1 2 Δ state was observed and fit; had been misassigned as D 2 Σ - in 1937. • Lifetimes of some A 2 Π levels were measured. We present the results of laser-ablation molecular jet experiments on the high-lying C 2 Π and 1 2 Δ electronic states of MgH, obtained via laser-induced fluorescence with frequency-doubled pulsed laser beams and with a visible-visible double resonance technique. The C 2 Π state is examined for the first time in nearly 50 years. The 1 2 Δ state was last reported in 1937, when it was misassigned as the D 2 Σ - state. These two states are fit with a modern standard Hamiltonian. Finally, measurements of the lifetime of the F 2 J = 1.5 f level in the v = 0 A 2 Π state are reported; lifetimes of levels of the C 2 Π state were very short (less than the 10 ns lower limit available in our experiment). [ABSTRACT FROM AUTHOR]