
Americium #
Orbitals and Energies #
Note – these are listed in BINDING ENERGY
Am 4d ≈ 832 eV
Am 4f ≈ 448 eV
Am 5d ≈ 108 eV
Am 6p ≈ 18 eV
Common Overlaps for Am 4f #
In 3d – Re 4p – Er 4s – Ti 2p – Ru 3p
Theory and Background #
The Am (4f) core level photoelectron spectrum from the clean metal is dominated by nearly symmetrical Am (4f7/2) and (4fs/2) peaks. Each peak is accompanied by a satellite located at approximately 4 eV lower binding energy from the main symmetrical peaks. The peaks are identical to previously reported data for Am metal [4] and are similarly attributed to “poorly” and “well” screened peaks. The main symmetrical peak is attributed to “poor screening” by (6d7s) conduction electrons. The satellite, at 4 eV lower binding energy, is due to “good screening” by 5f electrons; its intensity is weak since the 5f hybridization is poor, i.e., the 5f states are almost completely localized.(Taken directly from reference 1) Upon oxidation, the 5f electrons within Am are completely localised and there is no more partial hybridization. This results in the “well screened” contribution in the 4f emission no longer being present – though the “poorly screened” peak does not shift in binding energy. (1)
The oxide features shake-up features at a higher binding energy, characteristic of actinide dioxide spectra.(4) This satellite is a final-state effect common to actinide dioxides – the peak properties of which are dictated by total angular momentum (J), the hybridization of the system and the charge transfer energy (Δ). For more information – see the paper ‘Systematic Analysis of Core Photoemission Spectra for Actinide Di~Oxides and Rare-Earth Sesqui-Oxides’ by Akio Kotani and Takao Yamazaki.
Experimental Advice #
Not available
Data Analysis Guidance #
Appreciable knowledge of the electronics of these compounds aught be sought before any attempt to peak fit such spectra be undertaken. It is highly advised to treat such spectra as ‘fingerprints’ as a first case analysis without such knowledge.
References #
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- Nevitt, P. Photoemission studies of the light actinides. Ph.D. thesis, Cardiff University (2005).
- T.Gouder and F.Huber, Personal communication, 2005
- Wuilleumier, F., M. O. Krause, and D. A. Shirley. “Electron Spectroscopy.” (1972): 259.
- Kotani, Akio, and Takao Yamazaki. “Systematic analysis of core photoemission spectra for actinide di-oxides and rare-earth sesqui-oxides.” Progress of Theoretical Physics Supplement 108 (1992): 117-131.