Journal ArticleDiatomic AlCu has been interrogated using resonant two-photon ionization spectroscopy in a supersonic expansion of helium. The ground state is shown to be X l?+, deriving from the 3&3dgd configuration, in agreement with theoretical predictions. The closed-shell nature of this molecule results in a low density of electronic states, allowing the chemical bonding and electronic structure to be investigated in detail. Five excited electronic states have been observed and characterized, leading to a potential energy diagram based solely on experimental results. Constants experimentally determined for AlCu include a ground state bond length (r0) of 2.3389?0.0004 A, a dissociation energy, Do, of 2.315?0.012 eV, and an ionization potential of 7.065?.014 eV
