- Wavelength dispersive X-ray spectroscopy
The Wavelength dispersive X-ray spectroscopy (WDXRF or WDS) is a method used to count the number of
X-rays of a specific wavelength diffracted by a crystal. The wavelength of the impinging x-ray and the crystal's lattice spacings are related by Bragg's lawand produce constructive interference if they fit the criteria of Bragg's law. Unlike the related technique of Energy dispersive X-ray spectroscopyWDS reads or counts only the x-rays of a single wavelength, not producing a broad spectrum of wavelengths or energies. This generally means that the element must be known to find a crystal capable of diffracting it properly. The technique is often used in conjunction with EDS, where the general chemical make-up of an unknown can be learned from its entire spectrum. WDS is mainly used in chemical analysis, in an X-ray fluorescence spectrometer, or in an electron microprobe.
The X-rays emitted by the sample being analyzed are collimated by parallel copper blades (called "collimator" or "Soller slits"), and irradiate a known single
crystalat a precise angle. The single crystal diffracts the photons ( Bragg's law) which are collected by a detector, usually a scintillation counteror a proportional counter.
The single crystal, the specimen, and the detector are mounted precisely on a
goniometerwith the distance from the source of x-rays (the specimen) and the crystal equal to the distance from the crystal to the detector. It is usually operated under vacuum to reduce the absorption of soft radiation (low-energy photons) by the air and thus increase the sensitivity for the detection and quantitation of light elements (between boronand oxygen).
Modern systems contain a small number of crystals of known but differing properties, with automated changing of the crystal depending on the energy being analysed, enabling elements from the entire periodic table (excepting the very light elements) to be analyzed.
Energy dispersive X-ray spectroscopy
Wikimedia Foundation. 2010.
Look at other dictionaries:
Energy-dispersive X-ray spectroscopy — (EDS, EDX or EDXRF) is an analytical technique used for the elemental analysis or chemical characterization of a sample. As a type of spectroscopy, it relies on the investigation of a sample through interactions between electromagnetic radiation… … Wikipedia
X-ray — [ 22 December 1895 and presented to Professor Ludwig Zehnder of the Physik Institut, University of Freiburg, on 1 January 1896. The dark oval on the third finger is a shadow produced by her ring. [cite book last = Kevles first =Bettyann Holtzmann … Wikipedia
Characteristic x-ray — A high energy electron interacts with a bound electron in an atom and ejects it. The incident electron is scattered and the target electron gets displaced from its shell. The incident electron energy must exceed the binding energy of the electron … Wikipedia
X-ray photoelectron spectrometry — Spectrométrie de fluorescence X Pour les articles homonymes, voir SFX, FX et XRF. Un spectromètre de fluorescence X Philips PW1606 avec manutention automatiq … Wikipédia en Français
Emission spectroscopy — is a spectroscopic technique which examines the wavelengths of photons emitted by atoms or molecules during their transition from an excited state to a lower energy state. Each element emits a characteristic set of discrete wavelengths according… … Wikipedia
X-ray fluorescence — (XRF) is the emission of characteristic secondary (or fluorescent) X rays from a material that has been excited by bombarding with high energy X rays or gamma rays. The phenomenon is widely used for elemental analysis and chemical analysis,… … Wikipedia
Raman spectroscopy — Energy level diagram showing the states involved in Raman signal. The line thickness is roughly proportional to the signal strength from the different transitions. Raman spectroscopy ( … Wikipedia
Resonance Raman spectroscopy — Resonance Raman (RR) spectroscopy is a specialized implementation of the more general Raman spectroscopy. Overview As in Raman spectroscopy, RR spectroscopy provides information about the vibrations of molecules, and can also be used for… … Wikipedia
WDX — Wavelength Dispersive X ray Spectroscopy (Academic & Science » Electronics) *** Working Dog Excellent (Medical » Veterinary) *** Working Dog Excellent (Governmental » Military) *** Working Dog Excellent (Miscellaneous » Dogs Related) *** Working… … Abbreviations dictionary
List of materials analysis methods — List of materials analysis methods: Contents: Top · 0–9 · A B C D E F G H I J K L M N O P Q R S T U V W X Y Z μSR see Muon spin spectroscopy … Wikipedia