SUB-DOPPLER INTRACAVITY LASER SPECTROSCOPY OF CoO AND VO

A fluorescence cell inside the cavity of a standing wave dye laser has been used to record the hyperfine structure of some weak optical transitions of CoO and VO at sub-Doppler resolution. Second derivative line profiles with widths of 60 -- 100 MHz could be obtained by detecting the Lamb dips with frequency modulation of the laser. Portions of the three strongest sub-bands of CoO near 6400 $\\AA$ have been recorded. These sub-bands are parallel-polarized, and have the $X^{4}\\Delta$, $\\Omega = 7/2$ and 5/2 components as lower states; the upper states also have $\\Omega$ = 7/2 and 5/2, but appear to belong to two different close-lying electronic states. Interpretation of the upper state hyperfine parameters is complicated by extensive mixing of the electronic states, but the negative value for the Fermi contact parameter in the ground state confirms that its electron configuration is $\\sigma^{2}\\pi^{2} \\delta^{3}$. A similar study of the hyperfine structure in the (1,0) band of the $B^{4}\\Pi - X^{4}\\sum^{-}$ system of VO near 7370 $\\AA$ has been completed. The structure in the two least crowded and unperturbed sub-bands, $B^{4}\\Pi_{5/2, 3/2} - X^{4}\\sum^{-}$ has been analysed to show that the electron configuration of the $B^{4}\\Pi$ excited state is $\\pi\\delta^{2}$.