Wavelength dispersive X-ray spectroscopy

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

How the detector works

With WDS, the X-rays are broken down into their spectral components by diffraction on natural or synthetic crystals. The spectrometer is always set to a wavelength and thus the characteristic X-ray radiation of an element is analyzed. For a complete spectrum, the different wavelength ranges must be covered one after the other.

Comparison with energy dispersive X-ray spectroscopy

Compared to energy dispersive X-ray spectroscopy (EDS or EDX), which are more often found on electron microscopes , the detection sensitivity with a WDS is an order of magnitude better. At the same time, a significantly higher spectral resolution of the X-ray spectrum is achieved. The advantage of measuring with EDX, on the other hand, is the simultaneous measurement of the entire X-ray spectrum of the analyzed sample point and thus the simultaneous analysis of all elements. This means a clear time and speed advantage.

See also