Knowledge Bank

Band spectra of bismuth monofluoride in the 2750-5500 {\AA} region have been photographed and analyzed. Spectra were recorded in the 11th and 12th orders of a 7.3 m vacuum Ebert spectrograph and in the 3rd order of a 10 m vacuum Eagle spectrograph, with typical reciprocal dispersions of 2.5 and 1.4 {\AA}/mm in the first order. The analysis attributed the observed bands to two $O+-O+$ transitions, having a common lower state. A total of 40 bands from both systems have been rotationally analyzed. Molecular constants have been determined using the direct two state approach to the well known energy expression of a $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma -1\Sigma$ transition. The resulting over determined parameters were `merged’ to yield the minimum-variance linear unbiased estimate and associated error of each constant. A step-wise technique was utilized to handle the large number of constants involved. The separate merge fits to each transition were also merged to further consolidate the molecular constants. The lower state constants were found to be in excellent agreement with an earlier microwave study of the ground state of the $molecule.1$ The upper states have been found to mutually perturb one another. A brief discussion of these homogenous perturbations is given. R. K. R. curves and Franck-Condon factors will be presented.