AVS 62nd International Symposium & Exhibition
    Actinides and Rare Earths Focus Topic Thursday Sessions
       Session AC+AS+MI-ThM

Paper AC+AS+MI-ThM12
Resolving the Issues of 5f Covalency and Ionicity in UO2 and UF4

Thursday, October 22, 2015, 11:40 am, Room 230A

Session: Nuclear Power and Waste Remediation
Presenter: James Tobin, Lawrence Livermore National Laboratory
Correspondent: Click to Email
Building upon our recent work , a concerted effort to isolate and understand covalency and ionicity in uranium compounds has been pursued. Specifically,the isoelectronic formal charge systems, uranium dioxide and uranium tetrafluoride, have been investigated with a novel mixture of both soft and hardx-ray spectroscopies. The results to be discussed will include the following: (1)the use of soft X-ray O1s/F1s X-ray absorption spectroscopy (XAS) and U4d X-ray emission spectroscopy (XES) to follow the 2p/5f bonding via the unoccupied density of states; (2) the utilization of hard X-ray U L3 extended X-ray absorptionfine structure (EXAFS) to trivially distinguish the ordering in each: and (3) the use of hard X-ray L3 resonant X-ray emission spectroscopy (RXES) to distinguish 5f occupation/covalency effects in UO2 and UF4. Collaborators include CH Booth, DK Shuh, T. Tyliszczak, G. van der Laan, D. Sokaras, T.-C. Weng, D. Nordlund, S.-W. Yu, W. Siekhaus and P.S. Bagus.