Elements of Modern X-ray Physics , JensAls-Nielsen and DesMcMorrow Wiley, New York, 2001. $99.95, $29.95 paper (318 pp.). ISBN 0-471-49857-2, ISBN 0-471-49858-0 paper

Over its 25-year life span, synchrotron radiation has left an indelible mark on physics. This “leftover” radiation, once the bane of particle accelerator designers, has been found to be far more versatile than that produced by conventional sources. The parasitic use by condensed matter physicists spurred great creativity with the development of totally new, x-ray-based analytic tools that could exploit the brightness, coherence, and broad-spectral and temporal structure of synchrotron radiation. Thus were born such techniques as EXAFS (extended x-ray absorption fine structure), magnetic scattering, surface diffraction, fluorescence holography, and magnetic circular dichroism. Existing traditional uses of x rays, such as small-angle scattering, atomic core-level spectroscopy, radiography, topography, powder diffraction, diffuse scattering, and protein crystallography, were similarly able to benefit from the millionfold flux gains, and the radiation could be thereby applied to totally new classes of problems.

A facility sociology was thus thrust upon the once solitary x-ray branch of the condensed matter physics community, whose members learned to accept the demands for beamtime applications and user meetings. These physicists found that, by collaborating with their erstwhile rivals, they could build specialized endstation facilities that enabled all members to make progress far beyond the capabilities of their local institutions. With few exceptions, the appetite for more beamtime availability has been satisfied year after year by the skills of the accelerator physicists to design clever new insertion devices that amplify the usefulness of the x rays by concentrating them into brighter, narrower beams or narrower spectra. As each generation of sources reached its perceived limits, a breakthrough emerged that brought greater hope of future rewards. Until now, there has been a significant economy of scale in designing machines with so many beam ports that it has not been necessary to form vast, high-energy-like collaborations to carry out the important experiments. Sadly, this may have to change with the latest generation of linear-accelerator free-electron-laser sources being planned.

When a new field of physics emerges, critical ideas and information about methodology will often travel informally by word-of-mouth. Only when the field matures will the textbooks get written. This is particularly true of the synchrotron radiation community, where the informal channels of communication are augmented by the strong user network; users meet each other, sometimes frequently, because they work at the same central facilities. The network is further encouraged by the frequent user meetings. There are well-established, formal training programs such as Hercules, which has been held annually in Grenoble for 12 years and whose lecture materials have served as a substitute for textbooks in the community at large.

The publication of Jens Als-Nielsen and Des McMorrow’s Elements of Modern X-ray Physics is a defining moment in the field of synchrotron radiation, one that signals its maturity. The book combines in a single volume detailed descriptions of how the new sources work, how they are characterized, and how they affect the results of standard experiments. The reader is led through the topics of interactions with matter, sources, optical properties, diffraction (kinematical and dynamical), and absorption, all described from the synchrotron-radiation perspective. Examples and applications are kept to a minimum, introduced only to illustrate the principles. The physics is spread lavishly throughout the discussions, both as motivation and conclusion.

The level of Als-Nielsen and McMorrow’s textbook is appropriate for senior undergraduate or graduate students. Quantum mechanics (at the level of second quantization) and electromagnetism (Maxwell’s equations) are assumed, but the important radiation formulas are derived two ways: intuitively in the text and via Maxwell’s equations in an appendix. No prior knowledge of solid-state physics is assumed, since the concepts of lattices and phonons are introduced from scratch.

The pedagogy is strong, with most of the mathematical derivations elaborated in detail. A few derivations or formulas are original, in that they are omitted from other texts, either because they are approximate-but-useful (the form-factor expansion in exponentials, for example) or newly created. Some background concepts, such as the Dirac δ-function and Kramers–Kronig transform, are assigned to tinted text blocks so as not to interrupt the flow of arguments. Several of the derivations are intuitive, using either a commonsense or dimensional analysis approach.

Elements of Modern X-ray Physics will be a welcome addition to the bookshelves of synchrotron-radiation professionals and students alike. One of the book’s goals is to reach nonphysicist users of synchrotron radiation. I agree with the authors’ stated belief that “a greater knowledge of the underlying principles not only adds to the overall feeling of satisfaction, but also allows better experiments to be designed.” The text is now my personal choice for teaching x-ray physics.