Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 82: Nanostructure at Surfaces: Dots and Clusters

O 82.8: Talk

Thursday, March 19, 2015, 12:15–12:30, MA 043

XANES measurements and corresponding FEFF simulations on Ag clusters deposited in PDMS and silica aerogel — •Stefanie Roese, David Engemann, and Heinz Hövel — Fakultät Physik / DELTA, Technische Universität Dortmund

The knowledge of the geometric structure, size and electronic properties is essential for many applications of clusters.

Ag clusters produced in a supersonic expansion can be deposited without coalescence into matrix materials like silica aerogel or PDMS.

In addition to optical measurements X-ray absorption near edge structure spectroscopy (XANES) has developed as a powerful tool to determine geometric and electronic information about the sample. The measurements were carried out at the synchrotron radiation sources ESRF and DELTA.

The experimental data are compared to ab initio multiple scattering calculations (FEFF) [1] for different cluster sizes and structures like icosahedra and cuboctahedra. The comparison between the measured data and the simulations yields information about the geometric and electronic structure of the deposited clusters as well as about the influence of chemical environments. With the aid of the FEFF simulations the cluster aggregation process due to high deposition amounts can be visualized. Further, the reaction of the clusters with oxygen in the x-ray bam can be modeled.

[1] J. J. Rehr et al., Phys. Chem. Chem.Phys., 12, 5503-5513 (2010)