Probing the population of the spin-orbit split levels in the actinide 5f states

Journal Article · Wed Jul 14 04:00:00 EDT 2004 · Ultramicroscopy

OSTI ID:881891

Moore, K; der Laan, G v; Tobin, J; Chung, B; Wall, M; Schwartz, A

Spin-orbit interaction in the 5f states is believed to strongly influence exotic behaviors observed in actinides metals and compounds. Understanding these interactions and how they relate to the actinide series is of considerable importance. To address this issue, the branching ratio of the white-line peaks of the N4,5 edges for the light actinide metals, {alpha}-Th, {alpha}-U, and {alpha}-Pu were recorded using electron energy-loss spectroscopy (EELS) in a transmission electron microscope (TEM) and synchrotron-radiation-based x-ray absorption spectroscopy (XAS). Using the spin-orbit sum rule and the branching ratios from both experimental spectra and many-electron atomic spectral calculations, accurate values of the spin-orbit interaction, and thus the relative occupation of the j = 5/2 and 7/2 levels, are determined for the actinide 5f states. Results show that the spin-orbit sum rule works very well with both EELS and XAS spectra, needing little or no correction. This is important, since the high spatial resolution of a TEM can be used to overcome the problems of single crystal growth often encountered with actinide metals, allowing acquisition of EELS spectra, and subsequent spin-orbit analysis, from nm-sized regions. The relative occupation numbers obtained by our method have been compared with recent theoretical results and show a good agreement in their trend.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 881891
• Report Number(s): UCRL-JRNL-206133
• Journal Information: Ultramicroscopy, Journal Name: Ultramicroscopy Journal Issue: 4-5 Vol. 106; ISSN 0304-3991; ISSN ULTRD6
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION SPECTROSCOPY
ACTINIDES
BRANCHING RATIO
ELECTRON MICROSCOPES
ELECTRONS
ENERGY-LOSS SPECTROSCOPY
L-S COUPLING
MONOCRYSTALS
OCCUPATION NUMBER
OCCUPATIONS
SPATIAL RESOLUTION
SPECTRA
SUM RULES