Vibrational Quantum Analysis and Isotope Effect for the Lead Oxide Band Spectra

Abstract

Each strong line (${\mathrm{Pb}}^{206}$O) in the band spectrum emitted by a uranium lead arc in air is represented by three lines (${\mathrm{Pb}}^{208,\phantom{\rule{0ex}{0ex}}207,\phantom{\rule{0ex}{0ex}}206}$O with relative intensities in agreement with Aston) in the band spectrum from an ordinary lead arc. The first and second orders of a 21 ft. Rowland grating were used to make this comparison. The observed separations between corresponding band lines of isotopic molecules are in good agreement with the theory of the isotope effect in band spectra with PbO as the emitter.New measurements of the wave-lengths of the band heads were made from moderate dispersion spectrograms of the ordinary lead arc in air. The bands in the near ultra-violet form a new system** $\ensuremath{\nu}=30,197.0+[530.6({v}^{\ensuremath{'}}+\frac{1}{2})\ensuremath{-}1.05{({v}^{\ensuremath{'}}+\frac{1}{2})}^{2}]\ensuremath{-}[722.3({v}^{\ensuremath{'}\ensuremath{'}}+\frac{1}{2})\ensuremath{-}3.73{({v}^{\ensuremath{'}\ensuremath{'}}+\frac{1}{2})}^{2}]$ Three other systems in the visible have been discussed already by Mecke. Evidence in favor of combining two of these systems ($C$ and $B$) into one is presented. All of the band systems have a common lower state.