Optical spectroscopy of jet - cooled FeC between 12 000 and 18 100 cm 2 1

Iron monocarbide has been investigated between 12 000 and 18 100 cm in a supersonic expansion by resonant two-photon ionization spectroscopy. Six new electronic states have been identified for which origins relative to the ground state have been determined. Three of these possess V853, one possesses V854, and two possess V852. The V853 state with an origin near 13 168 cm is likely a D3 state and has been assigned as the analog of the @14.0# S←XS charge transfer transition in CoC. The V854 state is most likely a F4 state. Additionally, seven bands with V852 have been observed that have proven impossible to systematically group by electronic state. Because every transition rotationally resolved in this study possesses a lower state with V53, the ground state has been confirmed as arising from an V53 state that is most likely the V53 spin orbit component of a D i term derived from a 1d 9s configuration. The ionization energy ~IE! of FeC has been determined as 7.7460.09 eV by varying the wavelength of the ionization photon. When combined with the known IE of Fe and the bond energy of FeC, the bond energy of FeC is calculated to be 3.960.3 eV. Presentation of the results is accompanied by an analysis of the bonding in FeC from a molecular orbital standpoint. © 1997 American Institute of Physics. @S0021-9606~97!02746-3#