Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)

O 35.60: Poster

Dienstag, 27. März 2012, 18:15–21:45, Poster B

Ag clusters on SiO₂ and in matrices: effects of cluster-structure and surroundings — •Sabrina Hoffmann¹, Stefanie Duffe¹, Kamil Latussek¹, David Engemann¹, Christoph J. Sahle¹, Christian Sternemann¹, Heinz Hövel¹, Ralph Wagner², and Pieter Glatzel³ — ¹TU Dortmund, Experimentelle Physik I/DELTA, Dortmund, Germany — ²BU Wuppertal, Fachgruppe Physik-Materialwissenschaften, Wuppertal, Germany — ³ESRF, Grenoble, France

Embedding Ag clusters produced in a supersonic expansion using THECLA, a THErmal CLuster Apparatus [1,2] into a polydimethylsiloxane (PDMS) / SiO₂ aerogel matrix enables the investigation of a much higher amount of separated clusters [3] which on a SiO₂ substrate is limited by coalescence and electromagnetic coupling [2]. The plasmon resonances of Ag clusters on SiO₂ and in PDMS / SiO₂ aerogel before and after exposure to air were investigated by optical spectroscopy [4]. XANES measurements at the Ag L_1,2,3 absorption edges [5] carried out at the synchrotron radiation sources DELTA and ESRF were compared to ab initio multiple scattering calculations (FEFF) for different cluster sizes and structures.

[1] O. F. Hagena, Z. Phys. D 20, 425 (1991). [2] H. Hövel et al., Phys. Rev. B 48, 18178 (1993). [3] L. Ravagnan et al., J. Phys. D 42, 082005 (2009). [4] U. Kreibig et al., In: Advances in Metal and Semiconductor Clusters Vol. 4, (ed. M.A. Duncan), JAI press Inc., 345 (1998). [5] P. Behrens et al., Z. anorg. allg. Chem. 625, 111 (1999).