Knowledge Base

The Energies Listed are Binding Energies!   Cu 2p: 933 eV Cu 2s: 1096 eV Cu 3s: 120 eV Cu 3p: 74 eV

The Energies Listed are Binding Energies! Overlaps for Cu 2p (primary emission)

• Cs MNN (Al kα X-rays) (927 eV)
• I 3p (931 eV)
• Pr 3d 5/2 (932 eV)
• Bi 4s (939 eV)
• Sb 3s (944 eV)
• Mnn LMM (Al kα X-rays) (947 eV)
• Pr 3d 3/2 (953 eV)

Overlaps for Cu 3s

• Pr 4d (114 eV)
• Nd 4d (118 eV)
• Al 2s (119 eV)
• Pm 4d (121 eV)
• In 4s (122 eV)
• Ge 3p (122 eV)
• I 4p (123 eV)

Energies listed are Kinetic Energies!   Cu LMM: ~ 569.6 eV

When analysing copper it is imperative that you record the Cu LMM auger as well as the Cu 2p region. This is because the difference between Cu⁰ and Cu^I XPS spectra is very slight, and correct speciation identification may prove impossible without the auger region to assist (Figure 1).   Figure 1: Cu, Cu2O and CuO 2p and LMM auger XPS(1)

Due to the difficulties mentioned above, it is therefore common to use the modified auger parameter (α‘) to assign chemistry, values for which may be found in table 1. To find auger parameters of many more compounds, see reference 5 from Mark Biesinger.

The modified auger paramater may also provide insight into specific nanoparticle chemistry via estimation of the relaxation energy (r).⁽⁶⁾ This may be defined as half the change in the modified auger parameter compared to bulk Cu (equation 1).⁽⁷⁾ r = 0.5 * (|1851.2 – α‘) Equation 1 Copper nanoparticles may evidence increased relaxation energies when an decreased number of copper atoms are screening the core-hole (i.e. smaller nanoparticles)⁽¹⁾ or due to a decrease in the polarizability of the support.⁽⁸⁾ Copper metal does not exhibit a high degree of asymmetry, due to it’s largely filled d-band. A lineshape of LA(1.05, 110) can be used to give a good fit for Cu metal. Figure 2: Cu metal fit with LA(1.05, 110) lineshape When fitting copper doublets – do not constrain the FWHM of the doublets to be equal – due to the aforementioned Coster-Kronig broadening.