Why Satellite Peaks Appear in XPS (Explained Simply)
Satellite peaks can confuse even experienced XPS users.
This video explains what they are, why they appear, and how to eliminate them.
Satellite peaks in X-ray Photoelectron Spectroscopy (XPS) are additional peaks that appear at lower binding energies relative to the main photoelectron peak. These features originate from nonmonochromatic x-ray sources, where the characteristic Al Kα or Mg Kα radiation is accompanied by weaker high-energy components such as Kα₃–Kα₆ and Kβ lines.
When these higher-energy photons excite the sample, they generate additional photoelectrons with slightly lower measured binding energies, producing satellite peaks in the spectrum.
⭐ Why Satellite Peaks Appear
XPS systems using nonmonochromatic anodes irradiate the sample with:
• Main characteristic line (Mg Kα₁,₂ or Al Kα₁,₂)
• Additional higher-energy x-ray lines
• Bremsstrahlung background radiation
These extra photon energies eject electrons from the same core level but with different kinetic energies, resulting in shifted satellite peaks.
⭐ Common Satellite Sources
• Mg Kα₃ radiation
• Al Kα₃–Kα₆ contributions
• Kβ radiation from the x-ray anode
• Bremsstrahlung tail effects
These are well-known spectral distortions in nonmonochromatic XPS.
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