Purified polonium has been excited by high-frequency electrodeless discharges of 10, 30, and 400 Mc/sec at temperatures ranging from 200° to 800°C, and in an enclosed spark source. One hundred thirty-nine lines have been found in the spectrum from the electrodeless discharge. Thirty-five of these and thirteen additional lines have been observed in the spectrum of the spark discharge. Forty-eight lines have been classified as transitions involving twenty-four energy levels of Po I. Four levels of the fundamental configuration 6p4 have been identified. The observations have been compared with theoretical predictions for this configuration. Separations are well represented by theory with the parameter F2 = 1096K and ζ = 12 379K. The absolute value of the lowest level 6p43P2′ has been estimated from the first two members of the series 6p3(4S0)ns. An estimate of 67 980K is obtained. This corresponds to an ionization potential of 8.43 v for the neutral polonium atom.
G. W. CHARLES, D. J. HUNT, G. PISH, and D. L. TIMMA, "Preliminary Description and Analysis of the Spectrum of Polonium," J. Opt. Soc. Am. 45, 869-872 (1955)