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Interferometric measurement of Pb ii lines produced by hollow-cathode sources were made to improve the values of derived Pb ii energy levels. A total of 50 lines were measured with a Fabry-Perot interferometer, from which values for 29 even levels and 12 odd levels were derived. Where isotope or hyperfine structure was resolved, the data were adjusted to give the center of gravity of natural Pb.
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Wood et al. (1974) studied this question.
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