Mechanisms for Energy Shifts of Atomic K X Rays

The energies of the K-series X rays (Fig. 1) are for a given element almost independent of the source and the mode of excitation. Nevertheless, by means of suitably designed spectrometers, to be discussed in Sec. 2, it is possible to observe minute energy shifts. The main part of the present Chapter is devoted to experiments in which such shifts are observed, and to their interpretation.