Resonant two-photon ionization spectroscopy of jet-cooled RuC

A resonant two-photon ionization study of the jet-cooled RuC molecule has identified the ground state as a (1)Sigma(+) state arising from the 10 sigma(2)11 sigma(2)5 pi(4)2 delta(4). configuration. The (3)Delta(i) state arising from the 10 sigma(2)11 sigma(2)5 pi(4)2 delta(3)12 sigma(1) configuration lies very low in energy, with the (3)Delta(3) and (3)Delta(2) components lying only 76 and 850 cm(-1) above the ground state, respectively. Transitions from the X (1)Sigma(+), (3)Delta(3), and (3)Delta(2) states to the (II2)-I-3, (II1)-I-3, (3)Phi(3), (3)Phi(4), (1)Phi(3), and (II1)-I-1 states arising from the 10 sigma(2)11 sigma(2)5 pi(4)2 delta(3)6 pi(1) 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 r(0) = 1.608 Angstrom in the 2 delta(4), X (1)Sigma(+) state, to 1.635 Angstrom in the 2 delta(3)12 sigma(1), (3)Delta state, to 1.66 Angstrom in the 2 delta(3)6 pi(1), (II)-I-3 and (3)Phi states, to 1.667 Angstrom in the 2 delta(3)6 pi(1). (1)Phi and 1.678 Angstrom in the 2 delta(3)6 pi(1), (II)-I-1 state. A related decrease in vibrational frequency with electronic excitation is also observed. Hyperfine splitting is observed in the 2 delta(3)12 sigma(1), (3)Delta(3) state for the Ru-99(I= 5/2) C-12 and Ru-101(I= 5/2) C-12 isotopic combinations, This is analyzed using known atomic hyperfine parameters to show that the 12 sigma orbital is roughly 83% 5s(Ru) in character, a result in good agreement with previous work on the related RhC and CoC molecules. (C) 1998 American Institute of Physics. [S0021-9606(98)01442-1].