Cavity ring-down laser absorption spectroscopy of the E3Δ-X3Δ transition of VN

The (0,0) band of the electronic transition of VN near 450.5 nm has been investigated using the technique of laser vaporization/reaction with free jet expansion and cavity ring-down laser absorption spectroscopy. A new transition system was observed, which has been assigned as the E(3)Delta-X(3)Delta system. All three DeltaOmega = 0 subband transitions were recorded and rotationally analyzed. A least-squares fit of the measured line positions yielded molecular constants for the new E(3)Delta state. The bond length, r(0), of the E(3)Delta state was determined to be 1.6937 Angstrom, which is the longest among the known states of VN. The E(3)Delta state is expected to arise from the electronic configuration 1delta(1)10sigma(1), where the 10sigma orbital is an antibonding orbital. A comparison of the observed electronic states of VN to those of the isoelectronic TiO molecule supports the assignment.