- This article is mostly concerned with applications of synchrotron radiation. For details of the production of synchrotron light, see synchrotron and synchrotron radiation.
Synchrotron light is electromagnetic radiation produced by bending magnets and insertion devices (undulators or wigglers) in storage rings and free electron lasers. The major applications of synchrotron light are in condensed matter physics, material science, biology and medicine. A large fraction of experiments using synchrotron light involve probing the structure of matter from the sub-nanometer level of electronic structure to the micrometer and millimeter level important in medical imaging. An example of a practical industrial application is the manufacturing of microstructures by the LIGA process.
At a synchrotron facility, electrons are usually accelerated by a synchrotron, and then injected into a storage ring, in which they circulate, producing synchrotron radiation, but without gaining further energy. The radiation is projected at a tangent to the electron storage ring and captured by beamlines. These beamlines may originate at bending magnets, which mark the corners of the storage ring; or insertion devices, which are located in the straight sections of the storage ring. The spectrum and energy of X-rays differ between the two types. The beamline includes X-ray optical devices which control the bandwidth, photon flux, beam dimensions, focus, and collimation of the rays. The optical devices include slits, attenuators, crystal monochromators, and mirrors. The mirrors may be bent into curves or toroidal shapes to focus the beam. A high photon flux in a small area is the most common requirement of a beamline. The design of the beamline will vary with the application. At the end of the beamline is the experimental end station, where samples are placed in the line of the radiation, and detectors are positioned to measure the resulting diffraction, scattering or secondary radiation.
Experimental techniques and usage
Synchrotron light is an ideal tool for many types of research and also has industrial applications. Some of the experimental techniques in synchrotron beamlines are:
- Structural analysis of crystalline and amorphous materials
- Powder diffraction analysis
- Crystallography of proteins and other macromolecules
- Magnetic scattering
- Small angle X-ray scattering
- X-ray absorption spectroscopy
- Inelastic X-ray scattering
- X-ray imaging in phase contrast mode
- Photolithography for MEMS structures as part of the LIGA process.
- High pressure studies
- residual stress analysis
- X-Ray Multiple Diffraction
Some of the advantages of synchrotron light that allow for these practical uses are:
- High energy X-rays - short wavelength photons which can penetrate matter and interact with atoms.
- High concentration, tunability and polarization thus ensuring focusing accuracy for even the smallest of targets.
Compact synchrotron light sources
Because of the usefulness of tuneable collimated coherent electromagnetic X-Ray radiation, efforts have been made to make smaller more economical sources of the light produced by synchrotrons. One such effort has been undertaken by Lyncean Technologies, Inc. with their Compact Light Source (CLS). When compared to the size of the particle accelerators from which synchrotron light is derived, the CLS represents a 200 fold decrease in size. This reduction in scale should make synchrotron light accessible to many more labs and researchers.