Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 120: Ultra-fast phenomena II

HL 120.3: Vortrag

Freitag, 4. April 2014, 12:00–12:15, POT 006

Femtosecond Transmission Electron Diffraction on Single Crystalline Graphite — •Silvio Morgenstern, Christian Gerbig, Cristian Sarpe, Marlene Adrian, Arne Senftleben, and Thomas Baumert — University of Kassel, Institute of Physics and Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), D-34132 Kassel, Germany

In carbon layered materials (graphite, graphene) the electron subsystem, stimulated by optical excitations, is strongly coupled to a small set of optical phonons which limits the ballistic conductance. A detailed understanding of phonon decay mechanism is thus essential in improving the performance of carbon-based electronic devices [1,2]. Time-resolved electron diffraction has become a promising technique to observe dynamics at the molecular level with ultrafast precision [3,4]. We use a fs-transmission electron diffractometer to study the evolution of phonon decays in single crystalline graphite after ultrashort laser excitation. Our compact setup is well characterized [4] with excellent spatial-temporal resolution (coherence length > 8 nm, e-pulse duration < 200 fs [5]). In this contribution the generation and decay of coherent acoustic and optical phonons are discussed in dependence of film thickness down to few-layer graphene [6]. [1] T. Kampfrath et al., Phys. Rev. Lett. 95, 187403 (2005) [2] S. Schäfer et al., New J. Phys. 13, 063030 (2011) [3] M. Chergui & A. H. Zewail, Chem. Phys. Chem. 10, 28 (2009) [4] G. Sciaini & R. J. D. Miller, Rep. Prog. Phys 74, 096101 (2011) [5] C. Gerbig et al., submitted (2013) [6] C. Gerbig et al., in preparation (2013)