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Workshops

X-ray Spectroscopy : Recent Advances in Modelling and New Challenges

July 13, 2011 to July 15, 2011
Location : CECAM-ETHZ, Zurich, Switzerland
   Visa requirements

Organisers

  • Michael Odelius (University of Stockholm, Sweden)
  • Marcella Iannuzzi (University of Zurich, Switzerland)
  • Daniele Passerone (Swiss Federal Laboratories for Materials Testing and Research (EMPA), Switzerland)

Supports

   CECAM

ESF : Advanced Concepts in ab-initio Simulations of Materials

   Psi-k

Description

X-ray Absorption Fine Structure (XAFS) spectroscopy is a powerful technique for detailed structural and electronic characterisation of materials. By excitation of a core-electron, a local projection of the electronic structure is obtained. The development of synchrotron radiation sources has brought about new implications and applications in molecular and material sciences.

The analysis of the core-level spectra in combination with theoretical calculations discloses detailed electronic and structural information, such as charge transfer, nature of bonding, hybridization, chemical environment, site symmetry. Theoretical simulations of the spectra are essential not only tounderstand specific systems, but also to define the information content in these spectroscopic probes.

While rapid experimental improvements broaden the range of systems and processes that can be studied by time-resolved XAS, further developments on the data analysis and theory side are necessary to retrieve precise quantitative chemical information.

The aim of the workshop is to bring together experts in electronic structure code development, experimentalists, and computational scientists interested in state of the art core level x-ray spectroscopy simulations to discuss recent advances and future perspectives of the theoretical models.

We plan to invite keynote speakers to provide an overview of the present state in modelling of core level spectra, highlighting successes and limitations of the presented approaches. Leading experimentalists can give a flavor of the recent and future development on the experimental side. We hope to attract speakers from the diverse fields of application of x-ray spectroscopy to have a comprehensive picture of the typical problems being addressed, and to identify from a practical viewpoint the major deficiencies of the available computional tools.

Open discussions among experimentalists, scientists dealing with actual investigation of complex materials, and experts in electronic structure theory (method development and implementation) will be encouraged to come up with new solutions. In our opinion, it is desirable to analyze where to invest major effort in the development of computational tools to be able to provide clear support to real problems in materials science. 

 

During this workshop we would like to cover the following topics:

 

  • Simulation methods in core-level spectroscopy:Resonant photo-emission and resonant inelastic x-ray scattering
    •  -DFT and TDDFT 
    • - Ab initio methods -
    •  Bethe-Salpher equation / Multiple-scattering
  • Applications of x-ray spectroscopy (experiment and theory):   Time-resolved x-ray spectroscopy - experiment and theory
    • Catalysis, material science, 
    • liquids, macromolecules, polymers, and bio-systems

 

The goal is to gain insight into the following issues: 

 

  • Where do we understand the spectra and where not? Where do we see the major problems? Successful and not successful applications of core level spectroscopy simulations
  • Where does the support of theory become essential to understand the spectra?
  • Overview of available software for core level x-ray spectroscopy simulation. Different methods are optimally suited to address different systems and specific spectral features. How to choose the optimal approach?
  • Development of new algorithms:  is it worth to invest in new development?  DFT vs BSE
  • Calculation of the spectra in combination with molecular dynamics (MD) or Monte Carlo (MC) sampling. How important are ensemble averages and environment effects for solutions and soft matter?
  • Core excited state dynamics
  • Application to large scale complex systems: interfaces, solutions, bio-molecules, nanoparticles, solid-liquid interfaces under electrochemical polarization
  • Influence of high temperature on spectra and special issues that arise thereof
  • Present and future challenges for X-ray spectroscopy to investigate processes, reactions, transformation


References

[1] J. Stohr, “NEXAFS Spectroscopy”, Springer-Verlag, Berlin (1992).
[2] F. Gel’mukhanov, H. Ågren, “Resonant X-ray Raman scattering”, Phys. Rep. Rev. Sect. Phys. Lett.
312, 91–330 (1999).
[3] A. Kotani, S. Shin, “Resonant inelastic X-ray scattering spectra for electrons in solids”, Rev. Mod. Phys.
73, 203–46 (2001).
[4] F. de Groot, A. Kotani, “Core Level Spectroscopy of solids”, Taylor And Francis (2008).
[5] J.A Soinien, E.L Shirley, ”Scheme to calculate core hole-electron interactions in solids”, Phys. Rev. B
64,165112 (2001).
[6] A. Nilsson, L.G.M. Pettersson, “Chemical bonding on surfaces probed by X-ray emission spectroscopy
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[7] P. Wernet et al., “The structure of the first coordination shell in liquid water”, Science 304, 995–999
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[11] D. Sebilleau, R. Gunnella, Z.Y Wu, S. Di Matteo, C.R. Natoli, "Multiple-scattering approach with
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[13] A. Nilsson, L.G.M. Pettersson, J.K. Norskov, ”Chemical Bonding at Surfaces and Interfaces”, Elsevier
(2008)
[14] J.J. Rehr, J.J. Kas, F.D. Vila, M.P. Prange, K. Jorissen, Phys. Chem. Chem. Phys. 12, 5503–5513
(2010).
[15] J.A. van Bokhoven (guest editor), ”PCCP themed issue on recent developments in X-ray absorption
spectroscopy”, Phys. Chem. Chem. Phys. 12 (2010).
[16] A. Braun, D. Bayraktar, S. Erat, A.S. Harvey, D. Beckel, J.A. Purton, P. Holtappels, L.J. Gauckler, T.
Graule, "Pre-edges in oxygen (1s) X-ray absorption spectra: A spectral indicator for electron hole
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[17] http://www.anorg.chem.uu.nl/people/staff/FrankdeGroot/woXS/program.htm