Wavelength-dispersive X-ray spectroscopy

The wavelength dispersive x-ray spectroscopy (abbreviation: WDS or WDX ) is used for analysis of the characteristic X-ray radiation which is of a sample ( for example, due to the bombardment with an electron beam ) is emitted. In this way, all the elements having an atomic number of at least 4 (beryllium ) can be detected. The relative detection limit is 0.01 weight percent for elements, which corresponds to an absolute detection limit of 10-14 to 10-15 g. The process belongs to the group of X-ray spectroscopies, it is closely related to the energy-dispersive X-ray spectroscopy (EDS or EDX).

Operation of the detector

In the WDS X-ray radiation is dispersed by diffraction of natural or synthetic crystals in the spectral components. In this case, the spectrometer is always set to a wavelength and thus analysis of the characteristic X-rays of an element. Successively the different wavelength ranges have to be covered for a full range.

Comparison with the energy-dispersive X-ray spectroscopy

Compared with the energy-dispersive X-ray spectroscopy (EDS or EDX), which are more frequent in electron microscopes, the detection sensitivity of an order of magnitude better with a WDS. At the same time a significantly higher spectral resolution of the X-ray spectrum is achieved. Advantage of measuring with EDX is the simultaneous measurement of the entire X-ray spectrum of the analyzed sample location and thus the simultaneous analysis of all elements against. This means a significant time or speed advantage.