Photoelectron velocity-map imaging spectroscopy of nickel carbide: examination of the low-lying electronic states

The photoelectron detachment of nickel carbide anions has been characterized using photoelectron velocity-map imaging spectroscopy, allowing for a precise assignment of the electron affinity, vibrational frequencies, energy spacing and ordering of the low-lying electronic states. Additional insight into the chemical bonding and electronic structure of ground-state NiC has been achieved by a range of quantum chemical calculations. It is found that the triple-bonded (1)sigma(+) ground state probably mainly correlates with the Ni 3d(9)4s(1) state, so the triple bonds are better described as involving one electron-sharing sigma bond, one electron-sharing pi bond, and one Ni -> C dative pi bond.