Soft X-rays are a powerful probe of matter. They interact selectively with electrons in atoms and molecules and can be used to study atomic physics, chemical reactions, surfaces and solids, and biological entities. Over the past 20 years, synchrotrons have emerged as powerful sources of soft X-rays for experimental use. A new, third generation of synchrotron light sources is scheduled to start operation over the next few years, beginning in 1993. These facilities are distinguished by their ultra-low emittance electron beams and by their undulators - precisely engineered magnetic devices that cause the electrons passing through them to produce highly coherent X-rays and ultraviolet light of unprecedented spectral brightness. The book should prove a useful addition to the library of any scientist who needs information on the world's most advanced imaging and spectroscopic techniques.