High-Resolution Photoelectron Spectroscopy of the Ground and First Excited Electronic States of MgXe .

We report on the characterization of the X + 2 Σ + ground and the A + 2 Π Ω (Ω = 1/2, 3/2) and B + 2 Σ + electronically excited states of MgXe + . Rotationally cold MgXe in the a 3 Π 0 ( v ″ = 0) metastable electronic state was generated in a laser-ablation supersonic-beam source. Following single-photon excitation from the metastable state, the vibrational structure of the X + state of MgXe + was measured by pulsed-field-ionization zero-kinetic-energy photoelectron spectroscopy, and the adiabatic ionization energy of the X + ← a ionizing transition was determined to be E I /( hc ) = 37,468.3(6) cm -1 . Spectra of the A + ← X + and B + ← X + transitions were recorded by using the method of isolated-core Rydberg-dissociation spectroscopy. The observation of the Mg + (3p) 2 P 1/2 + Xe 1 S 0 dissociation limit enabled the determination of the dissociation energies of the X + [ D 0 (X + ) = 2970(7) cm -1 ] and A + states [ D 0 (A 1/2 + ) = 9781(7) cm -1 and D 0 (A 3/2 + ) = 9603(7) cm -1 ]. We compare these results with those of earlier experimental studies and ab initio quantum-chemical calculations.