# OPTICAL PUMPING OF THE $b^{4}\Sigma^{-}XII$ TRANSITION IN $NO^{\ast}$

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 Title: OPTICAL PUMPING OF THE $b^{4}\Sigma^{-}XII$ TRANSITION IN $NO^{\ast}$ Creators: Dyer, M. J.; Faris, G. W.; Cosby, P. C.; Huestis, D. L.; Slanger, T. G. Issue Date: 1993 Publisher: Ohio State University Abstract: The $NO(b^{4}\Sigma^{-})$ state, in $v = 2-5$, has been excited from the $X^{2}II$ ground state by optical pumping from 187 to 205 nm, and detected by $b^{4}-a^{4}II$ Ogawa band emission. This represents the first optical connection between the doublet and quartet systems and provides a foundation for investigations of the kinetics of the quartet states based on selective optical preparation. Simulation, using published spectroscopic $constants^{1,2}$, shows good agreement for the positions of low J transitions. Comparison of the simulated and observed intensities of the 24 rotational branches suggests that the b-X transition moment involves contributions from perturbers of all potential symmetries: $^{2}\Sigma, {^{2}}II,{^{2}}\Delta,{^{4}}\Sigma$, and $^{4}II$. The b-X Einstein coefficient is estimated to be about $103 s^{-1}$ based on comparison with $B^{2}-X^{2}II$ bands in the same spectral region. We have also investigated predissociation of $b^{4}\Sigma^{-} (v=6)$ and high-J levels of $b (v=5)$, and collisional production of $b^{4}\Sigma^{-}$ following optical excitation of the $A^{2}\Sigma^{+}\, B^{2}\Pi$, and $D^{2}\Sigma^{+}$ states. As most of the NO(b) radiates to the $NO(a^{4}II)$ state, this study also provides a means of preparing the low-v levels, principally $v = 1,2$, of the NO(a) state, whose kinetic importance has frequently been inferred, but for which no direct production scheme has been available. Description: $^{1}$. C. Amiot and J. Verges, J. Mol. Spectrosc. 81, 424 (1980). 2. K. P. Huber and M. Vervloet, J. Mol. Spectrosc. 129, 1 (1988). Author Institution: Molecular Physics Laboratory., SRI International URI: http://hdl.handle.net/1811/18461 Other Identifiers: 1993-MF-14