INTERFERENCE OF FLUORESCENCE X-RAYS AND COHERENT EXCITATION OF CORE LEVELS

The question of coherence in inelastic x-ray absorption and fluorescence processes among identical interacting atoms is studied using a simple diatomic model. Conditions for the coherence are discussed in terms of energy scales, such as the core hole lifetime, instrument energy resolutions, and the splitting of the electronic levels. As in the classical Young double-slit experiment, the primary requirement is that it be impossible to determine which atom has undergone the excitation-decay process. In contrast to the elastic scattering of x rays, noninteracting atoms do not contribute coherently to the inelastic scattering cross section. © 1995 American Institute of Physics.