X-Ray Fluorescence spectrometers (XRF) use high energy X-rays (or gamma rays) to excite fluorescent radiation or photons from a sample for elemental analysis. In wavelength dispersive x-ray fluorescence spectroscopy (WDXRF), photons emitted by the sample are separated or dispersed by diffraction before hitting the detector. This is accomplished by placing an analyzing crystal between the sample and the detector. Therefore, WDXRF spectrometers have better resolution than energy dispersive x-ray fluorescence spectrometers which do not contain an analyzing crystal. However, due to the increase in optical components, WDXRF spectrometers typical have a lower efficiency than EDXRF spectrometers and, hence, require a higher power x-ray tube (which can add to the cost of the instrument).
There are two types of WDXRF spectrometers: simultaneous and sequential. In simultaneous WDXRF spectrometers, multiple detectors placed at different angles are used to analyze multiple elements simultaneously. In sequential WDXRF Spectrometers, the crystal is turned while elements are analyzed sequentially. Sequential WDXRF spectrometers typically have better intensity, but take longer to record measurements. WDXRF is a nondestructive technique and has applications in many industries where elemental analysis is needed, such as geoscience, environmental analysis, food safety, and analyzing archeological artifacts.
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Energy Dispersive XRF Spectrometers (EDXRF)