X-ray Fluorescence

An electron from an outer shell then drops into the unoccupied orbital, to fill the Hole left behind. This transition gives off an X-ray of fixed, characteristic energy that can be detected by a Fluorescence detector. The energy needed to eject a core electron is characteristic of each element, and so is the energy emitted by the transition. The transition of an L shell electron dropping into the K Shell is termed a Kα transition, while an M shell electron dropping into the K shell is a Kβ transition.

When the energy source is a Synchrotron , the X-ray beam can be very small and very intense, and atomic information on the sub-micrometer scale can be obtained.

Typically the lightest element that can be analysed is Beryllium (Z = 4), but due to instrumental limitations and low x-ray yields for the light elements, it is often difficult to quantify elements lighter than Sodium (Z = 11).

There are two types of spectrometer:

on a single crystal before being detected;

Energy Dispersive spectrometers ( EDX or EDS ): the detector allows the determination of the energy of the photon when it is detected; the EDX spectrometers are smaller (even portable), cheaper, the measurement is faster, but the resolution and the detection limit is far worse than the WDX spectrometers.

OTHER SPECTROSCOPIC METHODS USING THE SAME PRINCIPLE

It is also possible to create a characteristic secondary X-ray emission with other incident radiation to excite the sample:

(or Castaing microprobe);

ion beam: Particle Induced X-ray Emission (PIXE).

(XPS), also called Electron Spectroscopy For Chemical Analysis (ESCA)

Auger Electron

Auger Electron Spectroscopy

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X-ray Fluorescence