Synchrotron Radiation and Its Origin

No single development has influenced the field of EXAFS spectroscopy more than the development of synchrotron radiation sources, particularly those based on electron (or positron) storage rings. These provide a continuum of photon energies at intensities that can be from 103 to 106 higher than those obtained with X-ray tubes, 

The most attractive features of synchrotron radiation have been summarized by Winick19 as  

We know from Maxwell s equations that whenever a charged particle undergoes acceleration, electromagnetic waves are generated. An electron in a circular orbit experiences an acceleration toward the center of the orbit and as a result emits radiation in an axis perpendicular to the motion. 

The fact that Ac is proportional to the bending radius is used in so-called insertion devices such as wiggler and undulator magnets.t Although a description of these is beyond the scope of this chapter, the basic principle behind these is to make the electron beam undergo sharp serpentine motions (thereby having a very short radius of curvature). The net effect is to increase the flux and the critical energy (see topmost curve in Fig. 5). 

Another very important property of synchrotron radiation is its very high degree of polarization. The radiation is predominantly polarized with the electric field vector parallel to the acceleration 

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