Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 29: Nanostructures at Surfaces III: Dots, Particles, and Clusters
O 29.2: Vortrag
Dienstag, 2. April 2019, 10:45–11:00, H25
Ultrafast librations of supported nanoclusters studied with femtosecond electron diffraction — •Thomas Vasileiadis1, Emmanuel Skountzos2, Dawn Foster3, Shawn Coleman4, Daniela Zahn1, Vlasis Mavrantzas2, Richard Palmer5, and Ralph Ernstorfer1 — 1Fritz-Haber-Institut, Faradayweg 4-6, 14195 Berlin, Germany — 2Department of Chemical Engineering, University of Patras — 3Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom — 4US Army Research Laboratory, Weapons and Materials Research Directorate — 5College of Engineering, Swansea University, Bay Campus, Fabian Way, Swansea SA1 8EN, United Kingdom
Femtosecond electron diffraction (FED) [1] can be used to probe ultrafast atomic motions in laser-excited bulk solids and nanoscale heterostructures [2]. In this work we show that, due to the sensitivity of diffraction in the crystal orientation, FED is sensitive to rotations of nanoclusters on a membrane. The investigated samples are size-selected Au nanoclusters with a partial (111) orientation on few-layer graphite. Optical excitation brings the nanoclusters and the substrate in non-equilibrium conditions. Due to substrate phonons, Au NCs perform ultrafast, constrained rotations, termed librations, which change the relative intensities of the various diffraction peaks in the picosecond timescale. References: [1] Waldecker et al. JAP 117, 044903 (2015). [2] Vasileiadis et al. ACS Nano 12 (8),7710-7720 (2018).