Frank de Groot is professor of X-ray Spectroscopy
in the Department of Chemistry at Utrecht
University. His work
reflects a concern with the theoretical and the experimental aspects of
X-ray spectroscopy, including both fundamental studies and applications.
His current interest is in the use of X-ray spectroscopies for the study
of the electronic and magnetic structure of condensed matter and
heterogeneous catalysts under working conditions. (extended
Google Scholar: list of publications
PhD theses open access PDF
of the PhD theses.
Research topic 1:
Interpretation of X-ray Absorption Spectroscopy
spectroscopy (XAS) is an important tool to determine the
electronic structure of molecules and materials. The power of x-ray
absorption experiments is that they can be performed under a
wide range of working conditions with high spatial and
The theoretical understanding of XAS
spectra of transition metal systems is divided into
(a) first principle
methods to simulate the 1s core excitations and
(b) cluster based semi-empirical charge transfer multiplet
calculations to simulate the 2p core excitations. For an overview see
Core Level Spectroscopy
of Solids. CTM4XAS
is a user-friendly interface that can be used
to simulate core level spectra (XAS, EELS, XPS, RIXS, Auger)
of transition metal and rare earth systems.
Research topic 2: Resonant Inelastic
X-ray Scattering (RIXS)
RIXS is a
spectroscopic technique that makes use of a
monochromator for both the x-rays that excite the
system as well as for the emitted x-rays.
photon-in photon-out experiment, RIXS can also be
adapted to various working conditions with a similar
large array of possibilities as XAS experiments.
52, 1170 (2013)
Research topic 3: In-situ X-ray spectromicroscopy of working
Transmission X-ray Microscopes can measure soft x-ray absorption
spectra with 20 nm spatial resolution. With the use of a nanoreactor
we have used STXM spectromicroscopy to image the chemistry of a
working catalyst at 1 bar working conditions. more. The 2012 showed
that one can now also measure hard x-ray absorption spectra with 20 nm
spatial resolution, at 10 bar working conditions.
124, 12152 (2012);