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Hyperfine structure of the (5d+6s)/sup 3/ configuration of /sup 139/La I: New measurements and ab initio multiconfigurational Dirac-Fock calculations

Journal Article · · Phys. Rev. A; (United States)

The atomic-beam laser-rf double-resonance method has been used to measure precisely the dipole and quadrupole hyperfine structure (hfs) of 11 levels of the 5d/sup 2/6s configuration and four levels of the 5d/sup 3/ configuration of /sup 139/La I. The results, together with earlier results for lower-lying levels, are compared in detail with new multiconfiguration Dirac-Fock (MCDF) ab initio calculations. The agreement is good to fair overall, but is poor in some areas. The comparison yields new insights and suggests areas in which the theoretical approach must be improved. In particular, the theory underestimates the importance of contact hfs in the 5d/sup 2/6s configuration by 25--40 %. In addition, there is at present no self-consistent way in the MCDF approach to take account of the large core polarization observed in the 5d/sup 3/ /sup 4/F term.

Research Organization:
Argonne National Laboratory, Argonne, Illinois 60439-4843
DOE Contract Number:
W-31109-ENG-38
OSTI ID:
5596210
Journal Information:
Phys. Rev. A; (United States), Journal Name: Phys. Rev. A; (United States) Journal Issue: 1 Vol. 37:1; ISSN PLRAA
Country of Publication:
United States
Language:
English