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Photoelectric absorption
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In a photoelectric absorption interaction, an incoming gamma-ray transfers virtually all of its energy to an atomic electron, usually the most tightly bound (K-shell) electron of an atom.

The atomic electron, now termed a photoelectron, is ejected from the atom with an energy equal to that of the initial gamma-ray minus the binding energy for the atomic electron:

Ee = Eg - Eb

Have a go Use the animation opposite to investigate the photoelectric effect.

The ejected electron is detected as a full energy peak in an energy spectrum. Photoelectric absorption facilitates the measurement of the energy of a gamma-ray photon. This interaction can also lead to the creation of x-ray fluorescence.

 

The University of Liverpool
1999, 2000 The University of Liverpool, Department of Physics

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