Knowledge Base

Doublet Separations

• Gd 3d: 31 eV
• Gd 4d: 6.7 eV
• Gd 5p: 0.6 eV

The Energies Listed are Binding Energies!

• Gd 3d: 1185 eV
• Gd 4s: 376 eV
• Gd 4p: 271 eV
• Gd 4d: 141 eV
• Gd 5s: 36 eV

The Energies Listed are Binding Energies!

Gd 3d

• Rh MNV (Al source) (1183 eV)
• Ce 3p (1186 eV)
• Zn 2s (1194 eV)
• Ca LMM (Al source) (1202 eV)
• Cs 3s (1217 eV)
• Ge 2p (1217 eV)
• C KLL (Al source) (1225 eV)

Gd 4d

• P 2p (136 eV)
• Zn 4s (137 eV)
• Tl 5s (137 eV)
• Sn 4s (137 eV)
• Pb 4f (138 eV)
• Fr 5p (140 eV)
• As 3p (141 eV)

Energies listed are Kinetic Energies!

Gd MNN: ~ 865 eV

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.

Reprinted from reference 5 with permission from American Physical Society – 06/12/24 (License number: RNP/24/DEC/086115)

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’ = |J_4f + J_3d|

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.

Reprinted from reference 5 with permission from American Physical Society – 06/12/24 (License number: RNP/24/DEC/086115)

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.

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.