Knowledge Base

Doublet Separations

• Am 4f: 14.3 eV
• Am 4d 50.5 – 51.1 eV
• Am 5d: 9.5 eV
• Am 6p: 13 eV

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)

Figure 1: Am (4f) core level spectra for increasing surface oxidation of Am metal (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. 

Figure 2: Am oxide prepared by reactive sputter deposition from an Am metal target in an oxygen atmosphere (2).