Dresden 2014 – scientific programme
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O: Fachverband Oberflächenphysik
O 62: Posters: Surface Reactions and Dynamics, Nanostructures
O 62.22: Poster
Wednesday, April 2, 2014, 17:30–21:00, P1
Simulations with FEFF of XANES spectra on Ag clusters deposited in PDMS and silica aerogel — •Stefanie Roese, David Engemann, and Heinz Hövel — Fakultät Physik / DELTA,Technische Universität Dortmund, 44227 Dortmund
For many applications of clusters such as catalysis the knowledge of geometrical structure, size and electronic properties is essential.
Depositing Ag clusters produced in a supersonic expansion into silica aerogel or PDMS can prevent the clusters from coalescence. Silica aerogel is a very porous compound of SiO2 nanoparticles containing up to 99 % empty space. PDMS is a polymer in which the clusters are dispersed by deposition.
The L2 and L3 edge of the Ag clusters is investigated with XANES carried out at the synchrotron radiation sources ESRF (ID 26) and DELTA (BL 8).
The experimental data are compared to ab initio multiple scattering calculations [1] for different cluster sizes and structures. The calculations include information about the geometric and electronic structure of the deposited clusters and also about their chemical environment. We examine cluster structures modeled with a Gupta potential [2] and compare the calculated XANES spectra to the measured ones.
The focus is here on the number of next neighbors and the next-neighbor distances to investigate the geometrical structure of the Ag clusters.
[1] J. J. Rehr et al., Phys. Chem. Chem.Phys., 12, 5503-5513 (2010)
[2] W. Huang et al., Chem. Phys. Lett., 507:199-202 (2011)