Resonant X-ray Raman scattering

An overview is presented of the theory of X-ray Raman scattering. Second-or der perturbation theory for the interaction between matter and light is use d as a common starting point, and the consequences of this theory are analy tically and numerically analyzed for a variety of experimental situations. The review focuses on results frost radiative and nonradiative scattering e xperiments conducted with 2nd and 3rd generation synchrotron radiation sour ces during the last couple of years, dealing with atomic, molecular, solid state and surface adsorbate targets. After giving a brief synopsis of relev ant experimental techniques, some basic theoretical concepts and principles of X-ray Raman scattering are described, followed by a presentation of the various particular aspects associated with the resonant X-ray scattering p rocess. That is: polarization interference - role of symmetry - symmetry br eaking and energy dependence - dissociation and time dependent interpretati ons - duration time and frequency detuning - formation of band profiles - D oppler effects - screening and chemical shifts - elastic scattering - solid state theory - application to surface adsorbates - absorption in the Raman mode - direct processes versus resonant X-ray scattering - many channel th eory. Each aspect is described by a qualitative picture, a mathematical ana lysis, and by illustrative examples from experiment combined in some cases with results from simulations. Simple systems are chosen to demonstrate the consequences of various aspects of the theory. (C) 1999 Elsevier Science B .V. All rights reserved.