Gadolinium #
Orbitals and Energies #
Note – these are listed in BINDING ENERGY
Gd 3d ≈ 1185 eV
Gd 4s ≈ 376 eV
Gd 4p ≈ 271 eV
Gd 4d ≈ 141 eV
Gd 5s ≈ 36 eV
Theory and Background #
Gadolinium exhibits significant multiplet splitting, as is common in f-block lanthanides.
Gd 3d5 #
The 3d region exhibits significant splitting, with the large spin-orbit doublet separation (~31 eV) of the tightly bound 3d electrons combining with coupling processes between these, and the 4f valence electrons to produce the complex spectra.
Gd valence shell has seven 4f electrons, with a total angular momentum of J = 7/2
The J=7/2 4f state couples with the J=5/2 3d state to form multiple final states, all described by the total angular momentum:
J’ = 6, 5, 4, 3, 2, 1
where J’ = |J4f + J3d|
J’ = 6 has the lowest binding energy, since all electron spins (in 4f and 3d) are aligned parallel.
J = 5/2 couples to form J’ = 5,4,3,2
In this case, J’ = 2 is the lowest energy, since the spins of the electrons are parallel, but opposite to the 3d orbital angular momentum.
Gd 4d #
The Gd 4d region also exhibits multiplet splitting, but may be preferable to analyse due to it’s higher kinetic energy, or relative simplicity – despite a lower photoionisation cross-section.
This region is, however, slightly complicated by an extrinsic energy-loss feature at 155 eV.
Experimental Advice #
Gadolinium is highly reactive and forms a thick native oxide layer Gd2O3 on its surface, typically 5-8 nm thick – and so if analysing Gd metal, one must sputter clean the surface beforehand. Typically, this may require multiple cleaning cycles per measurement as the surface reacts with low pressures of oxygen molecules in the analysis chamber.
Data Analysis Guidance #
Accurate modelling of Gd states for an unknown mixture would require a linear combination approach using well characterised and define standard reference spectra. It is advisable to analyse qualitatively (at least to start) unless you are an experience spectroscopist.
References #
- Islam, M. J., et al. (2020). “The effect of metal precursor on copper phase dispersion and nanoparticle formation for the catalytic transformations of furfural.” Applied Catalysis B: Environmental: 119062. Read it online here.
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- Vasquez, R. (1998). “Cu2O by XPS.” Surface Science Spectra 5(4): 257-261. Read it online here.
- Vasquez, R. (1998). “CuO by XPS.” Surface Science Spectra 5(4): 262-266. Read it online here.
- Biesinger, M. C. (2017). “Advanced analysis of copper X‐ray photoelectron spectra.” Surface and interface analysis 49(13): 1325-1334. Read it online here.
- Thøgersen, A., et al. (2008). “An experimental study of charge distribution in crystalline and amorphous Si nanoclusters in thin silica films.” Journal of Applied Physics 103(2): 024308. Read it online here.
- Moretti, G. (1998). “Auger parameter and Wagner plot in the characterization of chemical states by X-ray photoelectron spectroscopy: a review.” Journal of Electron Spectroscopy and Related Phenomena 95(2-3): 95-144. Read it online here.
- Batista, J., et al. (2001). “On the structural characteristics of γ-alumina-supported Pd–Cu bimetallic catalysts.” Applied Catalysis A: General 217(1-2): 55-68. Read it online here.
- Ghijsen, Jacques, et al. “Electronic structure of Cu 2 O and CuO.” Physical Review B 38.16 (1988): 11322. Read it online here.
