Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 86: Ultrafast Surface Dynamics I
O 86.2: Vortrag
Donnerstag, 10. März 2016, 15:15–15:30, S052
Electron-lattice interactions in gold clusters and islands studied with ultrafast electron diffraction — •Thomas Vasileiadis1, Dawn Wells2, Lutz Waldecker1, Roman Bertoni1, Richard Palmer2, and Ralph Ernstorfer1 — 1Department of Physical Chemistry, Fritz-Haber-Institut, Fardayweg 4-6 14195 Berlin Germany — 2Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Edgbaston Birmingham B15 2TT
Metallic nanoclusters possess a number of functionalities including catalytic activity and fluorescent emission that are absent from their bulk counterparts. In order to shed light into these confinement-induced properties, an in-depth understanding of the interactions between the subsystems of charge carriers and the lattice is essential. For this purpose we employ ultrafast electron diffraction to study size-selected gold nanoclusters and nanoislands supported by two-dimensional substrates. After laser excitation of the electronic subsystem, the evolution of lattice temperature and expansion can be probed from the intensity and position of diffraction peaks respectively. The so-called two-temperature-model allows for a quantification of how strongly the lattice couples to electronic excitations. The results are compared with thin films of gold that approach the bulk limit. We also discuss the effects that possibly rise due to electronic and vibrational coupling with the substrate.