Shake-Up & Shake-Off Peaks Explained (XPS Satellites)
Shake-up and shake-off satellite peaks are often misunderstood in XPS analysis.
This video explains what they are, why they appear, and how they help reveal the electronic structure of elements.
In X-ray Photoelectron Spectroscopy (XPS), not all peaks come from direct photoemission.
Some arise from additional electron–electron interactions inside the atom.
These satellite peaks, known as shake-up and shake-off features — contain valuable information about oxidation states, valence electron configuration, and chemical bonding.
⭐ What Are Shake-Up Peaks?
Shake-up satellites occur when the photoelectron leaves the atom while simultaneously exciting another electron to a higher energy state.
This energy loss shifts the satellite peak to a higher binding energy than the main peak.
Shake-up peaks often appear for transition metals, oxides, and compounds with partially filled d- or f-orbitals.
⭐ What Are Shake-Off Peaks?
Shake-off satellites occur when the outgoing photoelectron transfers energy to another electron that is completely ejected from the atom.
This process produces broad, lower-intensity features further from the main peak.
Shake-off helps identify:
• strongly correlated electron systems
• multiplet splitting
• valence band interactions
• complex chemical states
⭐ Why These Peaks Matter
Shake-up and shake-off features provide insight into:
• oxidation states
• hybridization
• screening effects
• unpaired electrons
• electron–electron correlation
Understanding them is essential for interpreting XPS spectra in:
• metal oxides
• catalysts
• transition metal compounds
• nanomaterials
• surface chemistry
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