Düsseldorf 2007 – wissenschaftliches Programm

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K: Fachverband Kurzzeitphysik

K 7: Laserstrahlwechselwirkungen

K 7.3: Vortrag

Dienstag, 20. März 2007, 15:45–16:00, 6E

X-ray study of acoustic transients in laser-excited Germanium — •Uladzimir Shymanovich, Matthieu Nicoul, Klaus Sokolowski-Tinten, Stephan Kähle, Alexander Tarasevitch, and Dietrich von der Linde — University Duisburg-Essen, Institut für experimentelle Physik, Lotharstr. 1, 47048 Duisburg

X-ray diffraction with femtosecond time-resolution allows to directly follow ultrafast structural changes in solids. Using femtosecond Titanium Kα X-ray pulses from a laser-driven plasma X-ray source, we have measured the transient acoustic lattice response of single crystalline, (111)-oriented, thin Germanium films after femtosecond optical excitation. An acoustic model which includes time-dependent thermal and electronic contributions to the laser-generated stress was combined with dynamical diffraction theory to calculate the transient changes in X-ray diffraction. Comparison of these calculations with the measured data allowed in particular to estimate the relative strength of electronic and thermal stress contributions.