Samarium
Doublet Separations
- Sm 3d: 23.2 eV
- Sm 4p: 18.2 eV
- Sm 5s: 2.8 eV
The Energies Listed are Binding Energies!
- Sm 3d: 1081 eV
- Sm 4s: 347 eV
- Sm 4p: 249 eV
- Sm 4d: 149 eV
- Sm 5s: 39 eV
- Sm 5p: 22 eV
- Sm 4f: 7 eV
The Energies Listed are Binding Energies!
Sm is primarily analyzed via the 3d orbital
- Ti LMM (Al source) (1070 eV)
- I 3s: 1073 eV
- Na 1s: 1073 eV
- Ac 4p: 1080 eV
- Ti MNN (Al source) (1083 eV)
- Cu 2s: 1096 eV
- Rn 4s: 1097 eV
- Ti MNN (Al source) (1110 eV)
- N KLL (Al source) (1112 eV)
- Ga 2p: 1116 eV
- La 3p: 1124 eV
Energies listed are Kinetic Energies!
Sm MNN: ~ 814 eV
The 3d core level in samarium is split into two distinct levels, 3d5/2 and 3d3/2, due to spin-orbit coupling. This splitting arises from the interaction between the electron’s spin and its orbital angular momentum. The energy difference between these two levels is approximately 26-27 eV. The 3d5/2 and 3d3/2 peaks are not just shifted versions of each other, but they also have different shapes.[5,6]
The 3d5/2 level has a higher degeneracy (six states) compared to the 3d3/2 level (four states). The ratio of their degeneracy is 3:2, which is also reflected in the ratio of their peak intensities when both are associated with the same valence state.[6]
The 3d core levels are further influenced by multiplet splitting caused by interactions with the 4f electrons. The 3d5/2 and 3d3/2 levels each exhibit their own multiplet structure, which is different for each level and is related to the number of unpaired 4f electrons. This contributes to the distinct shapes of the peaks. The 4f intra-atomic correlation energy is large, about 10 eV, and the energies of the 4f^n levels are well separated.[5,7]
The photoemission process creates a core hole, and the electronic structure of the atom reorganizes to screen this hole.[6] The final state effects are different for the 3d5/2 and 3d3/2 levels. This leads to shake-up and shake-off satellites which appear as shoulders or broadening on the main peaks, and the degree of satellite formation differs for the two levels. The 3d5/2 peak often has a more pronounced shoulder at a lower binding energy.[6,7]
Due to the low binding energy shoulder of the Sm 3d5/2 peak, it is recommended to record a few eV lower than expected to encompass the entire Sm 3d region and ensure a good background for fitting (e.g. begin at 1065-1070 eV for oxides, 1060-1065 for metal).
Due to the complexities of Sm XPS, it may be prudent to analyse spectra qualitatively, or in comparison with contemporarily acquired reference spectra.
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- Dufour, G., et al. “Atomic and chemical effects in Sm and Sm2O3 photoelectron spectra.” Chemical Physics Letters 42.3 (1976): 433-436. Read it online here.
- Krill, G., A. Amamou, and J. P. Senateur. “Valence changes of samarium ions in mixed SmS1-xPx compounds studied by photoemission (XPS and UPS).” Journal of Physics F: Metal Physics 10.8 (1980): 1889. Read it online here.
- Myhre, Kristian G., et al. “Samarium thin films molecular plated from N, N-dimethylformamide characterized by XPS.” Surface Science Spectra 25.2 (2018). Read it online here.
- Myhre, Kristian, Harry Meyer, and Miting Du. “Samarium and europium beta”-alumina derivatives characterized by XPS.” Surface Science Spectra 23.2 (2016): 102-111. Read it online here.
- Dufour, G., et al. “Atomic and chemical effects in Sm and Sm2O3 photoelectron spectra.” Chemical Physics Letters 42.3 (1976): 433-436. Read it online here.
- Brunckova, Helena, et al. “XPS characterization of SmNbO4 and SmTaO4 precursors prepared by sol-gel method.” Applied Surface Science 473 (2019): 1-5. Read it online here.
- Krill, G., A. Amamou, and J. P. Senateur. “Valence changes of samarium ions in mixed SmS1-xPx compounds studied by photoemission (XPS and UPS).” Journal of Physics F: Metal Physics 10.8 (1980): 1889. Read it online here.
