Rotationally resolved spectra of jet-cooled RuSi

We report the first gas-phase spectroscopic investigation of diatomic ruthenium silicide (RuSi). The molecules were produced by laser ablation of a Ru disk into a flow of helium carrier gas containing 0.5% SiH4, and were cooled in a supersonic expansion. The RuSi molecules were then studied using resonant two-photon ionization spectroscopy. Investigations conducted in the spectral range from 18 800 to 23 800 cm(-1) show a large number of excited vibronic levels that cannot readily be grouped into electronic band systems. The ground state is been demonstrated to be of (3)Delta(3) symmetry, deriving from the 2 delta(3)14 sigma(1) electronic configuration. Correcting for the effects of the spin-uncoupling operator, the ground state bond length (r(0)) is determined to be 2.0921 +/- 0.0004 A (1 sigma error limit). Diatomic RuSi is shown to have strong d pi-p pi bonds, unlike the isovalent AlCo molecule. (c) 2007 American Institute of Physics.