Introduction to Synchrotron Radiation
A continuous spectrum of photon radiation is produced when accelerated charged particles are deflected by electric or magnetic fields. For electron storage rings this radiation is produced by path bending magnets or insertion devices, and is called synchrotron radiation. It commonly spans energies from the far infrared to hard X-ray regions, has extremely small beam divergence and is orders of magnitude brighter than photons from X-ray tubes. The radiation is also strongly polarized in the plane of the storage ring, and has a pulsed structure in time, allowing for experiments that can resolve kinetic phenomena on the order of the pulse separation. Specialized insertion devices augment the radiation available from bending magnets. Wigglers essentially act as the sum of many bending magnets, producing high photon fluxes. Undulators produce interfering radiation fields that result in non-continuous spectral output, but extremely high brightness and high coherency. Other important X-ray optical elements include grazing-incidence mirrors for beam focusing, crystal monochromators for energy selection, zone-plate optical elements for nanoscale beam focusing and phase contrast microscopy, and detector systems for measuring high count rates with highenergy resolution. Present synchrotron facilities allow a number of powerful spectroscopic, diffraction, and imaging techniques to be widely available to a broad user base. Access to such facilities is also described.