ESR AND OPTICAL SPECTROSCOPY OF NbO IN INERT MATRICES AT $4^{\circ} K$; ESTABLISHMENT OF ITS ELECTRONIC CROUND STATE

Author Institution: Department of Chemistry, University of FloridaThe NbO molecule has been trapped in neon and argon matrices at $4^{\circ} K$ and investigated by ESR and optical spectroscopy. Analysis of the observed ESR spectra show that NbO has a $^{4}\Sigma^{-}$ electronic ground state derived from a $\sigma^{1}\delta^{2}$ configuration. Hyperfine constants due to interaction with $^{93}Nb$ (I = 9/2) and g tensor elements have been determined. In neon these magnetic parameters are $g_{\parallel} = 2.002, g_{\perp} = 1.958, A_{\parallel} = 1586.5$ MHz, and $A_{\perp} = 1646.6$ MHz. Both Nb $^{16}O$ and Nb $^{18}O$ have been studied optically. The $^{4}\Sigma^{-}$ - $^{4}\Sigma^{-}$ blue system of NbO appears at 461.4 nm (in Ne) while additional systems, possibly $^{4}\Pi$ - $^{4}\Sigma^{-}$, appear in the red. The vibrational frequency of ground state Nb $^{16}O$ (in Ne) is observed at $977.2 cm^{-1}$ in the infrared