A diffractometer is a

measuring instrument A measuring instrument is a device to measure a physical quantity. In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events. Est ...

for analyzing the structure of a material from the scattering pattern produced when a beam of radiation or particles (such as

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

s or

neutron The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beh ...

s) interacts with it.

Principle

Because it is relatively easy to use

electron The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no ...

s or

s having

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, t ...

s smaller than a nanometer, electrons and neutrons may be used to study crystal structure in a manner very similar to X-ray diffraction. Electrons do not penetrate as deeply into matter as X-rays, hence electron diffraction reveals structure near the surface; neutrons do penetrate easily and have an advantage that they possess an intrinsic magnetic moment that causes them to interact differently with atoms having different alignments of their magnetic moments. A typical diffractometer consists of a source of radiation, a

monochromator A monochromator is an optical device that transmits a mechanically selectable narrow band of wavelengths of light or other radiation chosen from a wider range of wavelengths available at the input. The name is from the Greek roots ''mono-'', "s ...

to choose the wavelength, slits to adjust the shape of the beam, a sample and a

detector A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon. In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends ...

. In a more complicated apparatus, a goniometer can also be used for fine adjustment of the sample and the detector positions. When an area detector is used to monitor the diffracted radiation, a beamstop is usually needed to stop the intense primary beam that has not been diffracted by the sample, otherwise the detector might be damaged. Usually the beamstop can be completely impenetrable to the X-rays or it may be semitransparent. The use of a semitransparent beamstop allows the possibility to determine how much the sample absorbs the radiation using the intensity observed through the beamstop. There are several types of X-ray diffractometer, depending on the research field (material sciences, powder diffraction, life sciences, structural biology, etc.) and the experimental environment, if it is a laboratory with its home X-ray source or a Synchrotron. In laboratory, diffractometers are usually an "all in one" equipment, including the diffractometer, the video microscope and the X-ray source. Plenty of companies manufacture "all in one" equipment for X-ray home laboratory, such as Rigaku, PANalytical,

Thermo Fisher Scientific Thermo Fisher Scientific Inc. is an American supplier of scientific instrumentation, reagents and consumables, and software services. Based in Waltham, Massachusetts, Thermo Fisher was formed through the merger of Thermo Electron and Fisher Sc ...

Bruker Bruker Corporation is an American manufacturer of scientific instruments for molecular and materials research, as well as for industrial and applied analysis. It is headquartered in Billerica, Massachusetts, and is the publicly traded parent compa ...

, and many others. There are fewer diffractometer manufacturers for synchrotrons, owing to few numbers of x-ray beamlines to equip and the need of solid expertise of the manufacturer. For material sciences, Huber diffractometers are widely known and, for structural biology, Arinax diffractometers are the reference. Nonetheless, due to few numbers of manufacturers, a large amount of synchrotron diffractometers are "homemade" diffractometers, realized by synchrotron engineering teams.

Uses

X-ray diffractometer instruments can be used for a variety of purposes including imaging crystal structures, phase determination, and identifying unfamiliar substances for use in crystallography, inspection, and pharmaceutical research for drug efficacy. A novel use of x-ray diffraction involves studying the surface of Mars to determine if it ever supported life.{{Cite thesis, title=Novel X-ray Diffraction and the Remote Analysis of Mars, url=https://leicester.figshare.com/articles/thesis/Novel_X-ray_Diffraction_and_the_Remote_Analysis_of_Mars/10220447/1, publisher=University of Leicester, date=2017-03-09, language=en-US, first=Stuart Matthew Robert, last=Turner

References

Measuring instruments

Principle

Uses

See also

References