ISOTOPIC SHIFTS AND NEW VTBRATIONAL ASSIGNMENTS FOR THE $A^{2}\Pi\mu - X^{2}\Pi_{g}$ SYSTEM OF $BO_{2}$

$^{1}$P. J, Hay, T. H. Dunning, Jr., and W, A. Goddard III, J. Chem. Phys. 62, 3912 (1975).$^{1}$ D. C. Frost, S. T. Lee, and C. A. McDowell, Chem. Phys. Lett. 24, 149 (1974); and C. R. Brundle, Chem. Phys. Lett. 26, 25 (1974).Author Institution: Department of Chemistry, The Ohio State University; Department of Chemistry, State University of New YorkThe analysis of the $BO_{2}$ absorption and fluorescence spectrum by $Johns^{1}$ provided one of the earliest examples of the Renner-Teller effect. Complementary studies of the emission spectrum by $Snowden^{2}$ and the resonance fluorescence spectrum by Russell et $al.^{3}$ provided additional data involving ground state rotational and vibrational constants. The present paper presents the results obtained from the analyses of the $A^{2}\Pi_{\mu} - X^{2}\Pi_{g}$ spectra produced with samples containing 92% boron-10 or 95% boron-11 and oxygen in natural abundance or oxygen containing 65% oxygen-18, Isotopic shifts are especially important for confirmation of vibrational assignments involving $\nu_{1}$ and $\nu_{2}$ since they are perturbed by Fermi resonance and the Renner-Teller effect. Rotational analyses (by $Johns^{1}$ and $Dymek^{4}$) of bands involving the (100-020) Fermi diads of both states established reliable vibrational assignments for these bands for $^{11}BO_{2}$ and $^{10}BO_{2}$. These results, along with the expected isotopic dependences, permit us to extend the vibrational assignments for $^{11}BO_{2}$ and $^{10}BO_{2}$, to make new assignments for the spectra obtained with oxygen-18, and to determine the ""best set"" of molecular constants for all isotopic combinations containing boron-10, boron-11, oxygcn-16, and oxygen-18