This self-contained text introduces readers to
the field of high-energy atomic physics - a new regime of photon-atom
interactions in which the photon energies significantly exceed the atomic or
molecular binding energies, and which opened up with the recent advent of new
synchrotron sources.







From a theoretical point of view, a small-parameter
characteristic of the bound system emerged, making it possible to perform
analytic perturbative calculations that can in turn serve as benchmarks for
more powerful numerical computations. The first part of the book introduces readers
to the foundations of this new regime and its theoretical treatment. In
particular, the validity of the small-parameter perturbation expansion and of
the lowest-order approximation is critically reviewed. The following chapters
then apply these insights to various atomic processes, such as photoionization
as a many-body problem, dominant mechanisms for the production of ions at
higher energies, Compton scattering and ionization accompanied by creation of
e-e+ pairs, and the photoionization of endohedral atoms (e.g. fullerene). Last
but not least, the computationally challenging transitions in the electron
shell during certain types of nuclear decays are investigated in detail.