Data are presented on the wavelengths of 97 lines of <sup>208</sup>Po and on the hyperfine structure of 31 lines of <sup>209</sup>Po. From these data, relative values of 26 energy levels of <sup>208</sup>Po I have been deduced. The hyperfinestructure splittings of 14 of these levels in <sup>209</sup>Po have been determined. Some tentative identifications of the levels have been made, based on a determination of the absolute value of the fundamental level 6<i>p</i><sup>4 3</sup><i>P</i><sub>2</sub>′ by application of a Ritz formula to three levels taken as 6<i>p</i><sup>3</sup>(<sup>4</sup><i>S</i>)<i>np</i><sup>5</sup><i>P</i><sub>3</sub>′, <i>n</i>=7,8,9. The ionization potential of <sup>208</sup>Po has been tentatively estimated as 8.41<sub>4</sub> V. From the measured splittings of the energy levels of the configuration 6<i>p</i><sup>4</sup> of <sup>209</sup>Po I, the nuclear magnetic moment of <sup>209</sup>Po is estimated to be 0.7<sub>6</sub> nm. Mrozowski’s identifications of some lines of Po I are examined. It is found that his identifications of the 4611 Å and 5940 Å lines are confirmed by coincidence of frequencies and by hyperfine-structure patterns, but that his identifications of the other lines and his determination of 6<i>p</i><sup>4</sup><sup>1</sup><i>S</i><sub>0</sub>′ could not be confirmed by the data of this investigation.
G. W. CHARLES, "Spectra of 208Po and the Hyperfine Structure of 209Po," J. Opt. Soc. Am. 56, 1292-1297 (1966)