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?3 symmetry, deriving from the 2?314?1 electronic configuration. Correcting for the effects of the spin-uncoupling operator, the ground state bond length (r0) is determined to be 2.0921?0.0004 ? (1? error limit). Diatomic RuSi is shown to have strong drr-prr bonds, unlike the isovalent AlCo molecule.