Measurement of spectrograms of electrodeless discharges in purified polonium has yielded over 450 red-shaded band heads in Po<sup>210</sup> and more than 500 heads in mixtures of Po<sup>208</sup>-Po<sup>209</sup>. Approximately 350 of these have been classified in a system concluded to be the principal system of Po-Po with the following constants (Po<sup>210</sup>-Po<sup>210</sup>): <i>T</i><sub>e</sub>′=25149.3K ω<sub>e</sub>′=108.532 K ω<sub>e</sub>′<i>x</i><sub>e</sub>′=-0.4417K ω<sub>e</sub>′=155.715K ω<sub>e</sub>″<i>x</i><sub>e</sub>″=-0.3353 K ω<sub>e</sub>″<i>y</i><sub>e</sub>″=-0.0003226 K. Observed and calculated isotope shifts are in close agreement. The dissociation energy of the lower state is calculated to be 1.895 v under the assumption that the dissociation products are normal polonium atoms.
G. W. CHARLES, D. L. TIMMA, D. J. HUNT, and G. PISH, "Vibrational Analysis of the Molecular Spectra of Polonium," J. Opt. Soc. Am. 47, 291-296 (1957)