Regensburg 2016 – scientific programme
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DS: Fachverband Dünne Schichten
DS 12: Postersession DS
DS 12.9: Poster
Monday, March 7, 2016, 17:00–19:00, Poster A
Ultrafast structural deformation studied by time-resolved x-ray diffraction — •Mathias Sander1, Azize Koc2, Christelle Kwamen2, Matthias Reinhardt2, Wolfram Leitenberger1, Peter Gaal2,3, and Matias Bargheer1,2 — 1Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25 14476 Potsdam — 2Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Wilhelm-Conrad-Röntgen Campus, Bessy II, Albert-Einstein-Str. 15, 12489 Berlin — 3Institute for Nanostructure and Solid State Physics, University of Hamburg, Jungiusstr. 11c/352, 20335 Hamburg
We investigate the ultrafast dynamics of coherent acoustic phonons in a photo-excited thin film. The excitation of the sample with an ultrashort laser pulse triggers coherent expansion and compression waves within the thin layer, which modulate the diffraction efficiency of an x-ray probe pulse on the picosecond timescale. A novel sample structure extinguishes the diffraction background from the laser deposited heat which is essential for repetition rates of 200kHz. The structure can be employed as ultrafast switchable mirror to shorten bursts of hard x-rays emitted from synchrotron storage rings. In addition, we study the in-plane sample dynamics by intersecting two optical pump pulses at the sample surface. The generated transient grating is characterized by x-ray reflection under grazing incidence and by reciprocal space mapping. The diffraction efficiency of the thermal grating can be tuned by the incoming laser fluence.