Ro-Vibrational Spectrum of Vanadium Monoxide (VO) at 10 μm.

The high resolution ro-vibrational spectrum of the diatomic molecule vanadium oxide (VO) in the gas phase was measured around 1000 cm^-1. In total, 1529 ro-vibrational transitions were assigned, in a spectral range of 984-1036 cm^-1. For many transitions, the hyperfine structure resulting from the nuclear spin of ⁵¹V were resolved and the molecular parameters for the first (v = 1) and second (v = 2) excited vibrational state of VO were derived. The molecules were generated using a laser ablation source in which a vanadium rod was laser ablated and gaseous nitrous oxide (N₂O) was introduced, as an oxygen donor. Subsequent supersonic adiabatic expansion cooled the molecules. The spectrum of VO was measured with quantum cascade lasers where the laser beams were perpendicularly oriented to the supersonic jet.