@article{NavirianSchickGaaletal.2014,
  author    = {Navirian, Hengameh A. and Schick, Daniel and Gaal, Peter and Leitenberger, Wolfram and Shayduk, Roman and Bargheer, Matias},
  title     = {Thermoelastic study of nanolayered structures using time-resolved X-ray diffraction at high repetition rate},
  series = {Applied physics letters},
  volume    = {104},
  journal   = {Applied physics letters},
  number    = {2},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0003-6951},
  doi       = {10.1063/1.4861873},
  pages     = {4},
  year      = {2014},
  abstract  = {We investigate the thermoelastic response of a nanolayered sample composed of a metallic SrRuO3 electrode sandwiched between a ferroelectric Pb(Zr0.2Ti0.8)O-3 film with negative thermal expansion and a SrTiO3 substrate. SrRuO3 is rapidly heated by fs-laser pulses with 208 kHz repetition rate. Diffraction of X-ray pulses derived from a synchrotron measures the transient out-of-plane lattice constant c of all three materials simultaneously from 120 ps to 5 mu s with a relative accuracy up to Delta c/c = 10(-6). The in-plane propagation of sound is essential for understanding the delayed out-of-plane compression of Pb(Zr0.2Ti0.8)O-3.},
  language  = {en}
}
@article{CuiYashchenokZhangetal.2014,
  author    = {Cui, Qianling and Yashchenok, Alexey and Zhang, Lu and Li, Lidong and Masic, Admir and Wienskol, Gabriele and Moehwald, Helmuth and Bargheer, Matias},
  title     = {Fabrication of Bifunctional Gold/Gelatin Hybrid Nanocomposites and Their Application},
  series = {ACS applied materials \& interfaces},
  volume    = {6},
  journal   = {ACS applied materials \& interfaces},
  number    = {3},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1944-8244},
  doi       = {10.1021/am5000068},
  pages     = {1999 -- 2002},
  year      = {2014},
  abstract  = {Herein, a facile method is presented to integrate large gold nanoflowers (similar to 80 nm) and small gold nanoparticles (2-4 nm) into a single entity, exhibiting both surface-enhanced Raman scattering (SERS) and catalytic activity. The as-prepared gold nanoflowers were coated by a gelatin layer, in which the gold precursor was adsorbed and in situ reduced into small gold nanoparticles. The thickness of the gelatin shell is controlled to less than 10 nm, ensuring that the small gold nanoparticles are still in a SERS-active range of the inner Au core. Therefore, the reaction catalyzed by these nanocomposites can be monitored in situ using label-free SERS spectroscopy. In addition, these bifunctional nanocomposites are also attractive candidates for application in SERS monitoring of bioreactions because of their excellent biocompatibility.},
  language  = {en}
}
@article{GaalSchickHerzogetal.2014,
  author    = {Gaal, Peter and Schick, Daniel and Herzog, Marc and Bojahr, Andre and Shayduk, Roman and Goldshteyn, Jevgeni and Leitenberger, Wolfram and Vrejoiu, Ionela and Khakhulin, Dmitry and Wulff, Michael and Bargheer, Matias},
  title     = {Ultrafast switching of hard X-rays},
  series = {Journal of synchrotron radiation},
  volume    = {21},
  journal   = {Journal of synchrotron radiation},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {0909-0495},
  doi       = {10.1107/S1600577513031949},
  pages     = {380 -- 385},
  year      = {2014},
  abstract  = {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.},
  language  = {en}
}
@article{SchickHerzogWenetal.2014,
  author    = {Schick, Daniel and Herzog, Marc and Wen, Haidan and Chen, Pice and Adamo, Carolina and Gaal, Peter and Schlom, Darrell G. and Evans, Paul G. and Li, Yuelin and Bargheer, Matias},
  title     = {Localized excited charge carriers generate ultrafast inhomogeneous strain in the multiferroic BiFeO3},
  series = {Physical review letters},
  volume    = {112},
  journal   = {Physical review letters},
  number    = {9},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {0031-9007},
  doi       = {10.1103/PhysRevLett.112.097602},
  pages     = {6},
  year      = {2014},
  abstract  = {We apply ultrafast x-ray diffraction with femtosecond temporal resolution to monitor the lattice dynamics in a thin film of multiferroic BiFeO3 after above-band-gap photoexcitation. The sound-velocity limited evolution of the observed lattice strains indicates a quasi-instantaneous photoinduced stress which decays on a nanosecond time scale. This stress exhibits an inhomogeneous spatial profile evidenced by the broadening of the Bragg peak. These new data require substantial modification of existing models of photogenerated stresses in BiFeO3: the relevant excited charge carriers must remain localized to be consistent with the data.},
  language  = {en}
}
@article{GoldshteynBojahrGaaletal.2014,
  author    = {Goldshteyn, Jevgeni and Bojahr, Andre and Gaal, Peter and Schick, Daniel and Bargheer, Matias},
  title     = {Selective preparation and detection of phonon polariton wavepackets by stimulated Raman scattering},
  series = {Physica status solidi : Physica status solidi},
  volume    = {251},
  journal   = {Physica status solidi : Physica status solidi},
  number    = {4},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0370-1972},
  doi       = {10.1002/pssb.201350114},
  pages     = {821 -- 828},
  year      = {2014},
  abstract  = {Wavevector-selective impulsive excitation of phonon-polaritons by a spectrally broad femtosecond transient grating produces wavepackets propagating in opposite directions. The photons in spectrally narrow probe pulses are scattered from these elementary excitations in lithium niobate (LiNbO3). Both elastically and inelastically scattered photons are simultaneously detected in a spectrometer. The Stokes- and anti-Stokes shifted probe pulses uniquely determine the propagation direction of the detected polariton wavepacket components and correspond to creation or annihilation of phonon-polaritons. Our experiments with spectrally broad pump and spectrally narrow probe pulses allows dissecting the four-wave-mixing process into two sequential stimulated Raman scattering events.},
  language  = {en}
}
@article{CuiShenYanetal.2014,
  author    = {Cui, Qianling and Shen, Guizhi and Yan, Xuehai and Li, Lidong and Moehwald, Helmuth and Bargheer, Matias},
  title     = {Fabrication of Au@Pt multibranched nanoparticles and their application to in situ SERS monitoring},
  series = {ACS applied materials \& interfaces},
  volume    = {6},
  journal   = {ACS applied materials \& interfaces},
  number    = {19},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1944-8244},
  doi       = {10.1021/am504709a},
  pages     = {17075 -- 17081},
  year      = {2014},
  abstract  = {Here, we present an Au@Pt core-shell multibranched nanoparticle as a new substrate capable of in situ surface-enhanced Raman scattering (SERS), thereby enabling monitoring of the catalytic reaction on the active surface. By careful control of the amount of Pt deposited bimetallic Au@Pt, nanoparticles with moderate performance both for SERS and catalytic activity were obtained. The Pt-catalyzed reduction of 4-nitrothiophenol by borohydride was chosen as the model reaction. The intermediate during the reaction was captured and clearly identified via SERS spectroscopy. We established in situ SERS spectroscopy as a promising and powerful technique to investigate in situ reactions taking place in heterogeneous catalysis.},
  language  = {en}
}
@article{SchickHerzogBojahretal.2014,
  author    = {Schick, Daniel and Herzog, Marc and Bojahr, Andre and Leitenberger, Wolfram and Hertwig, Andreas and Shayduk, Roman and Bargheer, Matias},
  title     = {Ultrafast lattice response of photoexcited thin films studied by X-ray diffraction},
  series = {Structural dynamics},
  volume    = {1},
  journal   = {Structural dynamics},
  number    = {6},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {2329-7778},
  doi       = {10.1063/1.4901228},
  pages     = {13},
  year      = {2014},
  abstract  = {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.},
  language  = {en}
}