Protactinium Pa I

Odd levels	Even levels
5f6d27s2 4H7 /2 1 978 5f6d37s 6I7/2 7 585 5f27s27p 4I9/2 11 445 5f37s2 4I9/2 13 019 5f26d7s7p 6L11/2 14 393 5f36d7s 6L11/2 22 500 ± 1 000 6d37s7p 6G3/2 24 000 ± 5 000 5f26d27p 6M13/2 25 106? 5f36d2 6M13/2 39 000 ± 2 000 5f37p2 6K9/2 44 500 ± 1 000	5f26d7s2 4K11/2 0 5f26d27s 6L11/2 7 000 5f6d7s27p 4I9/2 14 227 5f6d27s7p 6I7/2 15 061 5f26d3 6L11/2 22 000 ± 3 000 6d47s 6D1/2 22 000 ± 4 000 5f6d37p 6K9/2 22 000 ± 1 000 5f37s7p 6K9/2 25 600 ± 1 000 5f36d7p 6M13/2 37 500 ± 1 000

Ionization limit: 47 500 ± 1 000 cm^-1 (1) S.E.

(1) : J. Sugar, J. chem. Phys, U.S.A., 1974, 60, 4103