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O: Fachverband Oberflächenphysik

O 43: Surface Dynamics II

O 43.2: Vortrag

Mittwoch, 16. März 2011, 11:30–11:45, WIL B122

Anisotropy in time-resolved electron diffraction of bismuth films — •Carla Streubühr, Manuel Ligges, Thorsten Brazda, Uwe Bovensiepen, Ping Zhou, and Dietrich von der Linde — Universität Duisburg-Essen, Deutschland

With time-resolved electron diffraction we have investigated the excitation and relaxation of lattice vibrations in thin bismuth films after optical excitation with femtosecond laser pulses. Due to the property of the transmission electron diffraction from thin films, we are able to observe several diffraction orders at the same time. This provides us a complete view of the atomic motion.

The experiments showed a change in the diffraction intensity up to 300 ps after optical excitation, which depends on the azimuth angle of the diffraction order. This anisotropy depends on the polarization of the excitation pulses. We attribute this anisotropic intensity change to the excitation of polarized lattice vibrations by optical pulses. Possible excitation mechanisms of these lattice vibrations are impulsive stimulated Brillouin- or Raman- scattering.