Other X-ray related techniques

Protons can also be used instead of X-rays or electrons to create the initial vacancies in the inner electron shells, giving rise to a method known as proton induced X-ray emission (PIXE). In these instruments a high intensity, highly focused beam of protons is produced by a van de Graaff accelerator, 

This technique is also known as electron spectroscopy for chemical analysis (ESCA). Although it is concerned with the detection of electrons, it is discussed here because the way in which the photoelectrons are produced is fundamental to the XRF process. As described above, an incident X-ray photon produces an excited ion by ejecting an inner shell electron. The excited 

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