Editing X-ray fluorescence (section)

===Dispersion===
In energy-dispersive analysis, the fluorescent X-rays emitted by the material sample are directed into a solid-state detector which produces a "continuous" distribution of pulses, the voltages of which are proportional to the incoming photon energies. This signal is processed by a [[multichannel analyzer]] (MCA) which produces an accumulating digital spectrum that can be processed to obtain analytical data.

In [[Wavelength-dispersive X-ray spectroscopy|wavelength-dispersive]] analysis, the fluorescent X-rays emitted by the sample are directed into a [[diffraction grating]]-based [[monochromator]]. The diffraction grating used is usually a single crystal. By varying the angle of incidence and take-off on the crystal, a small X-ray wavelength range can be selected. The wavelength obtained is given by [[Bragg's law]]:

:<math> n \cdot \lambda = 2 d \cdot \sin(\theta)</math>

where ''d'' is the spacing of atomic layers parallel to the crystal surface.