Hello, when an atom is ionized (by electrons, ions, or X-rays) the deexcitation will - with a certain probability - leed to emission of Auger electrons. To detect them (by their characteristic energy) usually an electron spectrometer (CMA, HCA) must be used.

Auger electrons are associated with EDS, XFS. For all excitation events, there is a partition between Auger electrons and fluorescent photons and depends on the absorption edge and the size of the atom.

As you increase in atomic number (Z), fluorescent yield increases and auger electrons yield decreases.

Auger electrons will be more probably at low energy, and at L-edges (L2,3 < L1). This is why you generally don't see X-ray fluorescence experiments at low energy, but it is possible to generate exceptional spectra using a silicon drift detector (SDD) and I have done many experiments to show this.

Energy dispersive (proportional counters) detectors are not generally utilized in modern XAS experiments any more.