On angle-dependent resonant scattering (a.k.a. anomalous dispersion)

Norbert Peyerimhoff

Department of mathematical Sciences, Durham University, Durham, UK

e-mail: norbert.peyerimhoff@durham.ac.uk

The effect of resonant scattering is particularly significant if the energy of the incoming X-ray beam is close to the natural vibration energies (absorption edges) of some atomic electrons. Mathematically, this requires to add correction parameters f’ + i f’’ to the form factors f_0 for each atom. These correction parameters depend on the atom and the energy of the incoming X-ray beam. While it is generally assumed that their angular dependence can be neglected, our aim is to develop a quantitative theoretical evaluation of this assumption. In this talk, I will present Hoenl’s theory which allows to include this angle dependency and report on our joint work with Florian Kleemiss on such a quantitative theoretical evaluation.