@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{BojahrSchickMaertenetal.2012,
  author    = {Bojahr, Andre and Schick, Daniel and M{\"a}rten, Lena and Herzog, Marc and Vrejoiu, Ionela and von Korff Schmising, Clemens and Milne, Chris and Johnson, Steven Lee and Bargheer, Matias},
  title     = {Comparing the oscillation phase in optical pump-probe spectra to ultrafast x-ray diffraction in the metal-dielectric SrRuO3/SrTiO3 superlattice},
  series = {Physical review : B, Condensed matter and materials physics},
  volume    = {85},
  journal   = {Physical review : B, Condensed matter and materials physics},
  number    = {22},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {1098-0121},
  doi       = {10.1103/PhysRevB.85.224302},
  pages     = {6},
  year      = {2012},
  abstract  = {We measured the ultrafast optical response of metal-dielectric superlattices by broadband all-optical pump-probe spectroscopy. The observed phase of the superlattice mode depends on the probe wavelength, making assignments of the excitation mechanism difficult. Ultrafast x-ray diffraction data reveal the true oscillation phase of the lattice which changes as a function of the excitation fluence. This result is confirmed by the fluence dependence of optical transients. We set up a linear chain model of the lattice dynamics and successfully simulated the broadband optical reflection by unit-cell resolved calculation of the strain-dependent dielectric functions of the constituting materials.},
  language  = {en}
}
@article{BojahrHerzogSchicketal.2012,
  author    = {Bojahr, Andre and Herzog, Marc and Schick, Daniel and Vrejoiu, Ionela and Bargheer, Matias},
  title     = {Calibrated real-time detection of nonlinearly propagating strain waves},
  series = {Physical review : B, Condensed matter and materials physics},
  volume    = {86},
  journal   = {Physical review : B, Condensed matter and materials physics},
  number    = {14},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {1098-0121},
  doi       = {10.1103/PhysRevB.86.144306},
  pages     = {5},
  year      = {2012},
  abstract  = {Epitaxially grown metallic oxide transducers support the generation of ultrashort strain pulses in SrTiO3 (STO) with high amplitudes up to 0.5\%. The strain amplitudes are calibrated by real-time measurements of the lattice deformation using ultrafast x-ray diffraction. We determine the speed at which the strain fronts propagate by broadband picosecond ultrasonics and conclude that, above a strain level of approx. 0.2\%, the compressive and tensile strain components travel at considerably different sound velocities, indicating nonlinear wave behavior. Simulations based on an anharmonic linear-chain model are in excellent accord with the experimental findings and show how the spectrum of coherent phonon modes changes with time.},
  language  = {en}
}
@article{BojahrHerzogMitzscherlingetal.2013,
  author    = {Bojahr, Andre and Herzog, Marc and Mitzscherling, Steffen and Maerten, Lena and Schick, Daniel and Goldshteyn, J. and Leitenberger, Wolfram and Shayduk, R. and Gaal, P. and Bargheer, Matias},
  title     = {Brillouin scattering of visible and hard X-ray photons from optically synthesized phonon wavepackets},
  series = {Optics express : the international electronic journal of optics},
  volume    = {21},
  journal   = {Optics express : the international electronic journal of optics},
  number    = {18},
  publisher = {Optical Society of America},
  address   = {Washington},
  issn      = {1094-4087},
  doi       = {10.1364/OE.21.021188},
  pages     = {21188 -- 21197},
  year      = {2013},
  abstract  = {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.},
  language  = {en}
}
@article{BojahrGohlkeLeitenbergeretal.2015,
  author    = {Bojahr, Andre and Gohlke, Matthias and Leitenberger, Wolfram and Pudell, Jan-Etienne and Reinhardt, Matthias and von Reppert, Alexander and R{\"o}ssle, Matthias and Sander, Mathias and Gaal, Peter and Bargheer, Matias},
  title     = {Second Harmonic Generation of Nanoscale Phonon Wave Packets},
  series = {Physical review letters},
  volume    = {115},
  journal   = {Physical review letters},
  number    = {19},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {0031-9007},
  doi       = {10.1103/PhysRevLett.115.195502},
  pages     = {5},
  year      = {2015},
  abstract  = {Phonons are often regarded as delocalized quasiparticles with certain energy and momentum. The anharmonic interaction of phonons determines macroscopic properties of the solid, such as thermal expansion or thermal conductivity, and a detailed understanding becomes increasingly important for functional nanostructures. Although phonon-phonon scattering processes depicted in simple wave-vector diagrams are the basis of theories describing these macroscopic phenomena, experiments directly accessing these coupling channels are scarce. We synthesize monochromatic acoustic phonon wave packets with only a few cycles to introduce nonlinear phononics as the acoustic counterpart to nonlinear optics. Control of the wave vector, bandwidth, and consequently spatial extent of the phonon wave packets allows us to observe nonlinear phonon interaction, in particular, second harmonic generation, in real time by wave-vector-sensitive Brillouin scattering with x-rays and optical photons.},
  language  = {en}
}
@book{Bargheer2007,
  author    = {Bargheer, Matias},
  title     = {Videos mit R{\"o}ntgenblitzen : so schnell k{\"o}nnen Nanostrukturen funktionieren : Antrittsvorlesung 2007- 10-25},
  publisher = {Univ.-Bibl.},
  address   = {Potsdam},
  year      = {2007},
  abstract  = {In der Nanotechnologie und der molekularen Biologie werden immer kleinere Strukturelemente, wie beispielsweise einzelne Atomlagen oder Molek{\"u}lgruppen, manipuliert, um bestimmte Funktionen zu erzielen. Ver{\"a}nderungen in solchen Systemen laufen auf atomarer L{\"a}ngen- und Zeitskala ab. F{\"u}r das physikalische Verst{\"a}ndnis dieser ultraschnellen Prozesse ist ein anschauliches Bild wichtig. Dank ihrer hohen Struktur- und Zeitaufl{\"o}sung liefert die Femtosekunden-R{\"o}ntgenbeugung Bildsequenzen atomarer Bewegung von Molek{\"u}len und Festk{\"o}rpern und erm{\"o}glicht somit R{\"u}ckschl{\"u}sse {\"u}ber die komplexe Wechselwirkung zwischen Elektronen- und Kernbewegungen. Die aktuellen und zuk{\"u}nftigen M{\"o}glichkeiten, Atomen bei ihren Bewegungen zuzusehen, diskutiert der Referent an aktuellen Beispielen.},
  language  = {de}
}