My main research interest lies in the study of electronic structure using inner-shell spectroscopy. I am currently leading the scientifc program at an experimenal station (beamline ID26) of the European Synchrotron Radiation Facility (ESRF) in Grenoble/France where we explore the possibilities of hard X-ray absorption and emission spectroscopy (XAS-XES). The techniques that we use include resonant inelastic X-ray scattering (RIXS) or resonant X-ray emission spectroscopy (RXES).

Many researchers who use RIXS study effects that arise from the long range order, i.e. in systems that are described in reciprocal space and where the momentum transfer q is a crucial parameter (e.g. Ghiringhelli et al.). Experiments that do not take advantage of the long range order use other properties of the RIXS process that help to understand the local electronic structure and this is what I am mainly interested in.

RIXS finds applications in all fields of natural sciences. For a general discussion please read our introductions to XAS/XES/RIXS in Coord. Chem. Review and Photosynth. Res.. Some more specific aspects are addressed in reflections on hard X-ray photon-in/photon-out spectroscopy and we give some examples for RIXS in 3d transition metal K pre-edges.

The behaviour of charge transfer excitations in RIXS is nicely shown in our discussion on how to identify multi-electron excitations. An example for interference effects can be found in a demonstration of spectator and participator transitions in CeO2.

We also developed a little tool to prepare your XAS-XES experiment that can be used to estimate countrates and where we discuss possible spectral distortions due to incident beam self absorption effects (J. Synchro. Rad.).

Photon-in/photon-out spectroscopy includes:
  • Non-resonant X-ray emission (e.g. fluorescence) spectroscopy (XES) (e.g. valence-to-core XES on 3d TM: J. Am. Chem. Soc. 131 13161-13167 (2009))
  • Resonant inelastic X-ray scattering (RIXS), resonant X-ray emission spectroscopy (RXES)
  • Magnetic circular dichroism (MCD) combined with RIXS
  • Ultrafast XES
  • Range-extended X-ray absorption fine structure (EXAFS)
We have applied these techniques for example in
You find in the links to the right a short introduction to XAS-XES, my CV and a publication list.

This and That

Read the ESRF spotlight on RIXS-MCD

Visit the web page of the International X-Ray Absorption Society (IXAS)

Towards full coherence. Observed at Wiesele/Austria, Christmas 2012.