Dresden 2009 – scientific programme
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O: Fachverband Oberflächenphysik
O 46: Time-resolved spectroscopies I
O 46.5: Talk
Thursday, March 26, 2009, 11:30–11:45, SCH A315
Mechanical Oscillations of Nanostructures — •Richard Taubert1, Florian Hudert2, Albrecht Bartels2,3, and Thomas Dekorsy2 — 1Universität Stuttgart — 2Universität Konstanz — 3Gigaoptics GmbH, Konstanz, Deutschland
Understanding the mechanical properties of nanostructures has been a field of large interest during the last years. We present a method to investigate the phonon dynamics in nanostructures by time-resolved optical measurements. A new technique, Asynchronous Optical Sampling (ASOPS) is used to carry out pump-probe spectroscopy. Instead of using one laser and a mechanical delay line to generate pump- and probe-beams, two separated lasers, whose repetition rates are slightly detuned by several kHz are used. This allows the measurement of mechanical oscillations with GHz line width and a signal-to-noise ratio of 107 within 100 seconds of measurement time.
Time-resolved measurements on metallic and semiconductor superlattices as well as metallic nano-triangles and nano-tetrahedrons are presented. The measurements on the superlattices clearly resolve the first-order back-folded longitudinal acoustic phonons at the zone center. Furthermore, it is possible to do precise layer thickness and superlattice-period measurements. The mechanical oscillations of metallic triangles and pyramids with different edge lengths are observed and the influence of geometry, size and substrate are investigated.