Measurement of spectrograms of electrodeless discharges in purified polonium has yielded over 450 red-shaded band heads in Po210 and more than 500 heads in mixtures of Po208-Po209. Approximately 350 of these have been classified in a system concluded to be the principal system of Po-Po with the following constants (Po210-Po210): Te′=25149.3K ωe′=108.532 K ωe′xe′=-0.4417K ωe′=155.715K ωe″xe″=-0.3353 K ωe″ye″=-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)