Journal ArticleA resonant two-photon ionization study of the jet-cooled RuC molecule has identified the ground state as a 1?+ state arising from the 10?211?25rr42?4 configuration. The 3?i state arising from the 10?211?25rr42?312?1 configuration lies very low in energy, with the 3?3 and 3?2 components lying only 76 and 850 cm-1 above the ground state, respectively. Transitions from the X 1?+, 3?3 , and 3?2 states to the 3II2, 3II1, 3?3, 3?4, 1?3, and 1II1 states arising from the 10?211?25rr42?36rr1 configuration have been observed in the 12 700?18 100 cm-1 range, allowing all of these states to be placed on a common energy scale. The bond length increases as the molecule is electronically excited, from r051.608 ? in the 2?4, X 1?+ state, to 1.635 ? in the 2?312?1, 3? state, to 1.66 ? in the 2?36rr1, 3II and 3? states, to 1.667 ? in the 2?36rr1, 1? and 1.678 ? in the 2?36rr1, 1II state. A related decrease in vibrational frequency with electronic excitation is also observed. Hyperfine splitting is observed in the 2?312?1, 3?3 state for the 99Ru(I55/2)12C and 101Ru(I55/2)12C isotopic combinations. This is analyzed using known atomic hyperfine parameters to show that the 12? orbital is roughly 83% 5sRu in character, a result in good agreement with previous work on the related RhC and CoC molecules
