TY - JOUR A1 - Herzog, Marc A1 - Bojahr, Andre A1 - Goldshteyn, J. A1 - Leitenberger, Wolfram A1 - Vrejoiu, I. A1 - Khakhulin, D. A1 - Wulff, M. A1 - Shayduk, Roman A1 - Gaal, P. A1 - Bargheer, Matias T1 - Detecting optically synthesized quasi-monochromatic sub-terahertz phonon wavepackets by ultrafast x-ray diffraction JF - Applied physics letters N2 - We excite an epitaxial SrRuO3 thin film transducer by a pulse train of ultrashort laser pulses, launching coherent sound waves into the underlying SrTiO3 substrate. Synchrotron-based x-ray diffraction (XRD) data exhibiting separated sidebands to the substrate peak evidence the excitation of a quasi-monochromatic phonon wavepacket with sub-THz central frequency. The frequency and bandwidth of this sound pulse can be controlled by the optical pulse train. We compare the experimental data to combined lattice dynamics and dynamical XRD simulations to verify the coherent phonon dynamics. In addition, we observe a lifetime of 130 ps of such sub-THz phonons in accordance with the theory. KW - acoustic waves KW - epitaxial layers KW - phonon dispersion relations KW - terahertz waves KW - thin film devices KW - X-ray diffraction Y1 - 2012 U6 - https://doi.org/10.1063/1.3688492 SN - 0003-6951 VL - 100 IS - 9 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Bojahr, Andre A1 - Herzog, Marc A1 - Mitzscherling, Steffen A1 - Maerten, Lena A1 - Schick, Daniel A1 - Goldshteyn, J. A1 - Leitenberger, Wolfram A1 - Shayduk, R. A1 - Gaal, P. A1 - Bargheer, Matias T1 - Brillouin scattering of visible and hard X-ray photons from optically synthesized phonon wavepackets JF - Optics express : the international electronic journal of optics N2 - We monitor how destructive interference of undesired phonon frequency components shapes a quasi-monochromatic hypersound wavepacket spectrum during its local real-time preparation by a nanometric transducer and follow the subsequent decay by nonlinear coupling. We prove each frequency component of an optical supercontinuum probe to be sensitive to one particular phonon wavevector in bulk material and cross-check this by ultrafast x-ray diffraction experiments with direct access to the lattice dynamics. Establishing reliable experimental techniques with direct access to the transient spectrum of the excitation is crucial for the interpretation in strongly nonlinear regimes, such as soliton formation. Y1 - 2013 U6 - https://doi.org/10.1364/OE.21.021188 SN - 1094-4087 VL - 21 IS - 18 SP - 21188 EP - 21197 PB - Optical Society of America CY - Washington ER - TY - JOUR A1 - Gaal, P. A1 - Schick, Daniel A1 - Herzog, Marc A1 - Bojahr, Andre A1 - Shayduk, Roman A1 - Goldshteyn, J. A1 - Navirian, Hengameh A. A1 - Leitenberger, Wolfram A1 - Vrejoiu, Ionela A1 - Khakhulin, D. A1 - Wulff, M. A1 - Bargheer, Matias T1 - Time-domain sampling of x-ray pulses using an ultrafast sample response JF - Applied physics letters N2 - We employ the ultrafast response of a 15.4 nm thin SrRuO3 layer grown epitaxially on a SrTiO3 substrate to perform time-domain sampling of an x-ray pulse emitted from a synchrotron storage ring. Excitation of the sample with an ultrashort laser pulse triggers coherent expansion and compression waves in the thin layer, which turn the diffraction efficiency on and off at a fixed Bragg angle during 5 ps. This is significantly shorter than the duration of the synchrotron x-ray pulse of 100 ps. Cross-correlation measurements of the ultrafast sample response and the synchrotron x-ray pulse allow to reconstruct the x-ray pulse shape. Y1 - 2012 U6 - https://doi.org/10.1063/1.4769828 SN - 0003-6951 VL - 101 IS - 24 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Schick, Daniel A1 - Bojahr, Andre A1 - Herzog, Marc A1 - Gaal, P. A1 - Vrejoiu, I. A1 - Bargheer, Matias T1 - Following Strain-Induced Mosaicity Changes of Ferroelectric Thin Films by Ultrafast Reciprocal Space Mapping JF - Physical review letters N2 - We investigate coherent phonon propagation in a thin film of ferroelectric PbZr0.2Ti0.8O3 (PZT) by ultrafast x-ray diffraction experiments, which are analyzed as time-resolved reciprocal space mapping in order to observe the in-and out-of-plane structural dynamics, simultaneously. The mosaic structure of the PZT leads to a coupling of the excited out-of-plane expansion to in-plane lattice dynamics on a picosecond time scale, which is not observed for out-of-plane compression. Y1 - 2013 U6 - https://doi.org/10.1103/PhysRevLett.110.095502 SN - 0031-9007 SN - 1079-7114 VL - 110 IS - 9 PB - American Physical Society CY - College Park ER - TY - GEN A1 - Pavlenko, Elena S. A1 - Sander, Mathias A1 - Mitzscherling, Steffen A1 - Pudell, Jan-Etienne A1 - Zamponi, Flavio A1 - Rössle, Matthias A1 - Bojahr, Andre A1 - Bargheer, Matias T1 - Azobenzene – functionalized polyelectrolyte nanolayers as ultrafast optoacoustic transducers N2 - We introduce azobenzene-functionalized polyelectrolyte multilayers as efficient, inexpensive optoacoustic transducers for hyper-sound strain waves in the GHz range. By picosecond transient reflectivity measurements we study the creation of nanoscale strain waves, their reflection from interfaces, damping by scattering from nanoparticles and propagation in soft and hard adjacent materials like polymer layers, quartz and mica. The amplitude of the generated strain ε ∼ 5 × 10−4 is calibrated by ultrafast X-ray diffraction. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 297 Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-101996 VL - 8 SP - 13297 EP - 13302 ER - TY - JOUR A1 - Gaal, Peter A1 - Schick, Daniel A1 - Herzog, Marc A1 - Bojahr, Andre A1 - Shayduk, Roman A1 - Goldshteyn, Jevgeni A1 - Leitenberger, Wolfram A1 - Vrejoiu, Ionela A1 - Khakhulin, Dmitry A1 - Wulff, Michael A1 - Bargheer, Matias T1 - Ultrafast switching of hard X-rays JF - Journal of synchrotron radiation N2 - A new concept for shortening hard X-ray pulses emitted from a third-generation synchrotron source down to few picoseconds is presented. The device, called the PicoSwitch, exploits the dynamics of coherent acoustic phonons in a photo-excited thin film. A characterization of the structure demonstrates switching times of <= 5 ps and a peak reflectivity of similar to 10(-3). The device is tested in a real synchrotron-based pump-probe experiment and reveals features of coherent phonon propagation in a second thin film sample, thus demonstrating the potential to significantly improve the temporal resolution at existing synchrotron facilities. KW - ultrafast X-ray diffraction KW - thin film KW - coherent phonons KW - X-ray switching KW - pulse shortening KW - optical pump X-ray probe KW - time-resolved Y1 - 2014 U6 - https://doi.org/10.1107/S1600577513031949 SN - 0909-0495 SN - 1600-5775 VL - 21 SP - 380 EP - 385 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Maerten, Lena A1 - Bojahr, Andre A1 - Gohlke, Mathias A1 - Rössle, Matthias A1 - Bargheer, Matias T1 - Coupling of GHz Phonons to Ferroelastic Domain Walls in SrTiO3 JF - Physical review letters N2 - We study the linear and nonlinear acoustic response of SrTiO3 across its ferroelastic transition at T-a = 105 K by time domain Brillouin scattering. Above T-a we observe that for a strain amplitude of similar to 0.18% the sound velocity for compressive strain exceeds the tensile strain velocity by 3%. Below T-a we find a giant slowing down of the sound velocity by 12% and attribute this to the coupling of GHz phonons to ferroelastic twin domain walls. We propose a new mechanism for this coupling on the ultrafast time scale, providing an important new test ground for theories used to simulate atomic motion in domain forming crystals. Y1 - 2015 U6 - https://doi.org/10.1103/PhysRevLett.114.047401 SN - 0031-9007 SN - 1079-7114 VL - 114 IS - 4 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Schick, Daniel A1 - Shayduk, Roman A1 - Bojahr, Andre A1 - Herzog, Marc A1 - von Korff Schmising, Clemens A1 - Gaal, Peter A1 - Bargheer, Matias T1 - Ultrafast reciprocal-space mapping with a convergent beam JF - JOURNAL OF APPLIED CRYSTALLOGRAPHY N2 - A diffractometer setup is presented, based on a laser-driven plasma X-ray source for reciprocal-space mapping with femtosecond temporal resolution. In order to map out the reciprocal space, an X-ray optic with a convergent beam is used with an X-ray area detector to detect symmetrically and asymmetrically diffracted X-ray photons simultaneously. The setup is particularly suited for measuring thin films or imperfect bulk samples with broad rocking curves. For quasi-perfect crystalline samples with insignificant in-plane Bragg peak broadening, the measured reciprocal-space maps can be corrected for the known resolution function of the diffractometer in order to achieve high-resolution rocking curves with improved data quality. In this case, the resolution of the diffractometer is not limited by the convergence of the incoming X-ray beam but is solely determined by its energy bandwidth. Y1 - 2013 U6 - https://doi.org/10.1107/S0021889813020013 SN - 0021-8898 VL - 46 IS - 10 SP - 1372 EP - 1377 PB - WILEY-BLACKWELL CY - HOBOKEN ER - TY - JOUR A1 - Schick, Daniel A1 - Herzog, Marc A1 - Bojahr, Andre A1 - Leitenberger, Wolfram A1 - Hertwig, Andreas A1 - Shayduk, Roman A1 - Bargheer, Matias T1 - Ultrafast lattice response of photoexcited thin films studied by X-ray diffraction JF - Structural dynamics N2 - Using ultrafast X-ray diffraction, we study the coherent picosecond lattice dynamics of photoexcited thin films in the two limiting cases, where the photoinduced stress profile decays on a length scale larger and smaller than the film thickness. We solve a unifying analytical model of the strain propagation for acoustic impedance-matched opaque films on a semi-infinite transparent substrate, showing that the lattice dynamics essentially depend on two parameters: One for the spatial profile and one for the amplitude of the strain. We illustrate the results by comparison with high-quality ultrafast X-ray diffraction data of SrRuO3 films on SrTiO3 substrates. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. Y1 - 2014 U6 - https://doi.org/10.1063/1.4901228 SN - 2329-7778 VL - 1 IS - 6 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Pavlenko, Elena S. A1 - Sander, Mathias A1 - Mitzscherling, S. A1 - Pudell, Jan-Etienne A1 - Zamponi, Flavio A1 - Roessle, M. A1 - Bojahr, Andre A1 - Bargheer, Matias T1 - Azobenzene - functionalized polyelectrolyte nanolayers as ultrafast optoacoustic transducers JF - Nanoscale N2 - We introduce azobenzene-functionalized polyelectrolyte multilayers as efficient, inexpensive optoacoustic transducers for hyper-sound strain waves in the GHz range. By picosecond transient reflectivity measurements we study the creation of nanoscale strain waves, their reflection from interfaces, damping by scattering from nanoparticles and propagation in soft and hard adjacent materials like polymer layers, quartz and mica. The amplitude of the generated strain epsilon similar to 5 x 10(-4) is calibrated by ultrafast X-ray diffraction. Y1 - 2016 U6 - https://doi.org/10.1039/c6nr01448h SN - 2040-3364 SN - 2040-3372 VL - 8 SP - 13297 EP - 13302 PB - Royal Society of Chemistry CY - Cambridge ER -