Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 9: Poster 1

HL 9.4: Poster

Montag, 23. März 2009, 14:30–17:00, P2

Temperature-dependent Measurements of Phonon Dynamics in Highly Oriented Pyrolytic Graphite — •Martin Scheuch¹, Konrad von Volkmann¹, Luca Perfetti², Tobias Kampfrath¹, Christian Frischkorn¹, and Martin Wolf¹ — ¹Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin — ²Laboratoire des Solides Irradiés, Ecole polytechnique, 91128 Palaiseau cedex, France

We have employed THz time-domain spectroscopy in the range from 10 to 30 THz to obtain the complex dielectric function of Highly Oriented Pyrolytic Graphite (HOPG) for temperatures from 10 to 300 K. In addition to static measurements, we apply a pump pulse at 790 nm to investigate the dynamics of the energy dissipation of the photo-excited charge carriers. Our data allow us to evaluate the lifetimes of various strongly coupled high-energy phonon modes [1]. Agreement with theoretical predictions [2] is good and yields the coupling strength between these high-energy and other low-energy phonon modes. Our results are relevant to graphene and carbon nanotubes, which are closely related to graphite.

[1] T. Kampfrath et al., PRL 95, 187403 (2005) [2] N. Bonini et al., PRL 99, 176802 (2007)