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Preparing an Isotopically Pure 229Th Ion Beam for Studies of 229mTh
Published on: May 3, 2019
Energy Levels and Classified Lines in the Second Spectrum of Thorium (Th II)
Romuald Zalubas1, Charles H Corliss1
1Institute for Basic Standards, National Bureau of Standards, Washington, D.C. 20234.
Abstract:
The analysis of Th II has been extended with improved observations of the spectrum between 2000 and 25 000 Å. About 6500 lines are classified as transitions between 199 odd levels and 271 even levels. Of the 192 levels expected from the six odd configurations 5f(6d + 7s)2 and (6d + 7s)27p, 188 are now known. In the even level system, all but one of the 37 levels of the three (6d + 7s)3 configurations are known. Of the 268 levels predicted for the configurations 5f 27s + 5f7s7p + 5f6d7p + 5f 26d, 235 are now known. The identifications are based on the theoretical calculations by N. Minsky. New Zeeman effect observations have increased the number of levels with known g-values to 406 out of 470 known levels. The classifications will be useful in establishing secondary standards of wavelength.
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