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

Iron monocarbide has been investigated between 12 000 and 18 100 cm21 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 ?"=3, one possesses ?'=4, and two possess ?'=2. The ?'=3 state with an origin near 13 168 cm-1 is likely a 3?3 state and has been assigned as the analog of the [14.0]??+ ?X??+ charge transfer transition in CoC. The ?'=4 state is most likely a 3?4 state. Additionally, seven bands with ?'=2 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 ?=3, the ground state has been confirmed as arising from an ?=3 state that is most likely the ?=3 spin orbit component of a 3?i term derived from a 1?39?1 configuration. The ionization energy (IE) of FeC+ has been determined as 7.74?0.09 eV by varying the wavelength of the ionization photon. When combined with the known IE of Fe and the bond energy of FeC1, the bond energy of FeC is calculated to be 3.9?0.3 eV. Presentation of the results is accompanied by an analysis of the bonding in FeC from a molecular orbital standpoint.