@article{LiebigSarhanPrietzeletal.2018,
  author    = {Liebig, Ferenc and Sarhan, Radwan Mohamed and Prietzel, Claudia Christina and Th{\"u}nemann, Andreas F. and Bargheer, Matias and Koetz, Joachim},
  title     = {Undulated Gold Nanoplatelet Superstructures},
  series = {Langmuir},
  volume    = {34},
  journal   = {Langmuir},
  number    = {15},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0743-7463},
  doi       = {10.1021/acs.langmuir.7b02898},
  pages     = {4584 -- 4594},
  year      = {2018},
  abstract  = {Negatively charged flat gold nanotriangles, formed in a vesicular template phase and separated by an AOT-micelle-based depletion flocculation, were reloaded by adding a cationic polyelectrolyte, that is, a hyperbranched polyethylenimine (PEI). Heating the system to 100 degrees C in the presence of a gold chloride solution, the reduction process leads to the formation of gold nanoparticles inside the polymer shell surrounding the nanoplatelets. The gold nanoparticle formation is investigated by UV-vis spectroscopy, small-angle X-ray scattering, and dynamic light scattering measurements in combination with transmission electron microscopy. Spontaneously formed gold clusters in the hyperbranched PEI shell with an absorption maximum at 350 nm grow on the surface of the nanotriangles as hemispherical particles with diameters of similar to 6 nm. High-resolution micrographs show that the hemispherical gold particles are crystallized onto the {111} facets on the bottom and top of the platelet as well as on the edges without a grain boundary. Undulated gold nanoplatelet superstructures with special properties become available, which show a significantly modified performance in SERS-detected photocatalysis regarding both reactivity and enhancement factor.},
  language  = {en}
}
@article{vonReppertWilligPudelletal.2018,
  author    = {von Reppert, Alexander and Willig, Lisa and Pudell, Jan-Etienne and Roessle, M. and Leitenberger, Wolfram and Herzog, Marc and Ganss, F. and Hellwig, O. and Bargheer, Matias},
  title     = {Ultrafast laser generated strain in granular and continuous FePt thin films},
  series = {Applied physics letters},
  volume    = {113},
  journal   = {Applied physics letters},
  number    = {12},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0003-6951},
  doi       = {10.1063/1.5050234},
  pages     = {5},
  year      = {2018},
  abstract  = {We employ ultrafast X-ray diffraction to compare the lattice dynamics of laser-excited continuous and granular FePt films on MgO (100) substrates. Contrary to recent results on free-standing granular films, we observe in both cases a pronounced and long-lasting out-of-plane expansion. We attribute this discrepancy to the in-plane expansion, which is suppressed by symmetry in continuous films. Granular films on substrates are less constrained and already show a reduced out-of-plane contraction. Via the Poisson effect, out-of-plane contractions drive in-plane expansion and vice versa. Consistently, the granular film exhibits a short-lived out-of-plane contraction driven by ultrafast demagnetization which is followed by a reduced and delayed expansion. From the acoustic reflections of the observed strain waves at the film-substrate interface, we extract a 13\% reduction of the elastic constants in thin 10 nm FePt films compared to bulk-like samples. (C) 2018 Author(s).},
  language  = {en}
}
@article{LiebigSarhanPrietzeletal.2018,
  author    = {Liebig, Ferenc and Sarhan, Radwan Mohamed and Prietzel, Claudia Christina and Schmitt, Clemens Nikolaus Zeno and Bargheer, Matias and Koetz, Joachim},
  title     = {Tuned Surface-Enhanced raman scattering performance of undulated Au@Ag triangles},
  series = {ACS applied nano materials},
  volume    = {1},
  journal   = {ACS applied nano materials},
  number    = {4},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {2574-0970},
  doi       = {10.1021/acsanm.8b00570},
  pages     = {1995 -- 2003},
  year      = {2018},
  abstract  = {Negatively charged ultraflat gold nanotriangles (AuNTs) stabilized by the anionic surfactant dioctyl sodium sulfosuccinate (AOT) were reloaded with the cationic surfactant benzylhexadecyldimethylammonium chloride (BDAC). Because of the spontaneous formation of a catanionic AOT micelle/BDAC bilayer onto the surface of the reloaded AuNTs, a reduction of Ag+ ions leads to the formation of spherical silver nanoparticles (AgNPs). With increasing concentration of AgNPs on the AuNTs, the localized surface plasmon resonance (LSPR) is shifted stepwise from 1300 to 800 nm. The tunable LSPR enables to shift the extinction maximum to the wavelength of the excitation laser of the Raman microscope at 785 nm. Surface-enhanced Raman scattering (SERS) experiments performed under resonance conditions show an SERS enhancement factor of the analyte molecule rhodamine RG6 of 5.1 X 10(5), which can be related to the silver hot spots at the periphery of the undulated gold nanoplatelets.},
  language  = {en}
}
@misc{SarhanKoopmanSchuetzetal.2018,
  author    = {Sarhan, Radwan Mohamed and Koopman, Wouter-Willem Adriaan and Schuetz, Roman and Schmid, Thomas and Liebig, Ferenc and Koetz, Joachim and Bargheer, Matias},
  title     = {The importance of plasmonic heating for the plasmondriven photodimerization of 4-nitrothiophenol},
  series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  number    = {698},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-42719},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-427197},
  pages     = {8},
  year      = {2018},
  abstract  = {Metal nanoparticles form potent nanoreactors, driven by the optical generation of energetic electrons and nanoscale heat. The relative influence of these two factors on nanoscale chemistry is strongly debated. This article discusses the temperature dependence of the dimerization of 4-nitrothiophenol (4-NTP) into 4,4′-dimercaptoazobenzene (DMAB) adsorbed on gold nanoflowers by Surface-Enhanced Raman Scattering (SERS). Raman thermometry shows a significant optical heating of the particles. The ratio of the Stokes and the anti-Stokes Raman signal moreover demonstrates that the molecular temperature during the reaction rises beyond the average crystal lattice temperature of the plasmonic particles. The product bands have an even higher temperature than reactant bands, which suggests that the reaction proceeds preferentially at thermal hot spots. In addition, kinetic measurements of the reaction during external heating of the reaction environment yield a considerable rise of the reaction rate with temperature. Despite this significant heating effects, a comparison of SERS spectra recorded after heating the sample by an external heater to spectra recorded after prolonged illumination shows that the reaction is strictly photo-driven. While in both cases the temperature increase is comparable, the dimerization occurs only in the presence of light. Intensity dependent measurements at fixed temperatures confirm this finding.},
  language  = {en}
}
@article{SteteSchossauBargheeretal.2018,
  author    = {Stete, Felix and Schossau, Phillip and Bargheer, Matias and Koopman, Wouter-Willem Adriaan},
  title     = {Size-Dependent coupling of Hybrid Core-Shell Nanorods},
  series = {The journal of physical chemistry : C, Nanomaterials and interfaces},
  volume    = {122},
  journal   = {The journal of physical chemistry : C, Nanomaterials and interfaces},
  number    = {31},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1932-7447},
  doi       = {10.1021/acs.jpcc.8b04204},
  pages     = {17976 -- 17982},
  year      = {2018},
  abstract  = {Owing to their ability of concentrating electromagnetic fields to subwavelength mode volumes, plasmonic nanoparticles foster extremely high light-matter coupling strengths reaching far into the strong-coupling regime of light matter interaction. In this article, we present an experimental investigation on the dependence of coupling strength on the geometrical size of the nanoparticle. The coupling strength for differently sized hybrid plasmon-core exciton-shell nanorods was extracted from the typical resonance anticrossing of these systems, obtained by controlled modification of the environment permittivity using layer-by-layer deposition of polyelectrolytes. The observed size dependence of the coupling strength can be explained by a simple model approximating the electromagnetic mode volume by the geometrical volume of the particle. On the basis of this model, the coupling strength for particles of arbitrary size can be predicted, including the particle size necessary to support single-emitter strong coupling.},
  language  = {en}
}
@misc{SteteSchossauKoopmanetal.2018,
  author    = {Stete, Felix and Schossau, Phillip Gerald and Koopman, Wouter-Willem Adriaan and Bargheer, Matias},
  title     = {Size Dependence of the Coupling Strength in Plasmon-Exciton Nanoparticles},
  series = {Quantum Nano-Photonics},
  journal   = {Quantum Nano-Photonics},
  publisher = {Springer},
  address   = {Dordrecht},
  isbn      = {978-94-024-1546-9},
  issn      = {1871-465X},
  doi       = {10.1007/978-94-024-1544-5_26},
  pages     = {381 -- 383},
  year      = {2018},
  abstract  = {The coupling between molecular excitations and nanoparticles leads to promising applications. It is for example used to enhance the optical cross-section of molecules in surface enhanced Raman scattering, Purcell enhancement or plasmon enhanced dye lasers. In a coupled system new resonances emerge resulting from the original plasmon (ωpl) and exciton (ωex) resonances as ω±=12(ωpl+ωex)±14(ωpl-ωex)2+g2---------------√, (1) where g is the coupling parameter. Hence, the new resonances show a separation of Δ = ω+ - ω- from which the coupling strength can be deduced from the minimum distance between the two resonances, Ω = Δ(ω+ = ω-).},
  language  = {en}
}
@misc{SteteKoopmanBargheer2018,
  author    = {Stete, Felix and Koopman, Wouter-Willem Adriaan and Bargheer, Matias},
  title     = {Signatures of strong coupling on nanoparticles},
  series = {Quantum Nano-Photonics},
  journal   = {Quantum Nano-Photonics},
  publisher = {Springer},
  address   = {Dordrecht},
  isbn      = {978-94-024-1546-9},
  issn      = {1871-465X},
  doi       = {10.1007/978-94-024-1544-5_53},
  pages     = {445 -- 447},
  year      = {2018},
  abstract  = {The electromagnetic coupling of molecular excitations to plasmonic nanoparticles offers a promising method to manipulate the light-matter interaction at the nanoscale. Plasmonic nanoparticles foster exceptionally high coupling strengths, due to their capacity to strongly concentrate the light-field to sub-wavelength mode volumes. A particularly interesting coupling regime occurs, if the coupling increases to a level such that the coupling strength surpasses all damping rates in the system. In this so-called strong-coupling regime hybrid light-matter states emerge, which can no more be divided into separate light and matter components. These hybrids unite the features of the original components and possess new resonances whose positions are separated by the Rabi splitting energy h Omega. Detuning the resonance of one of the components leads to an anticrossing of the two arising branches of the new resonances omega(+) and omega(-) with a minimal separation of Omega = omega(+) - omega(-).},
  language  = {en}
}
@article{PudellMaznevHerzogetal.2018,
  author    = {Pudell, Jan-Etienne and Maznev, A. A. and Herzog, Marc and Kronseder, M. and Back, Christian H. and Malinowski, Gregory and von Reppert, Alexander and Bargheer, Matias},
  title     = {Layer specific observation of slow thermal equilibration in ultrathin metallic nanostructures by femtosecond X-ray diffraction},
  series = {Nature Communications},
  volume    = {9},
  journal   = {Nature Communications},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {2041-1723},
  doi       = {10.1038/s41467-018-05693-5},
  pages     = {7},
  year      = {2018},
  abstract  = {Ultrafast heat transport in nanoscale metal multilayers is of great interest in the context of optically induced demagnetization, remagnetization and switching. If the penetration depth of light exceeds the bilayer thickness, layer-specific information is unavailable from optical probes. Femtosecond diffraction experiments provide unique experimental access to heat transport over single digit nanometer distances. Here, we investigate the structural response and the energy flow in the ultrathin double-layer system: gold on ferromagnetic nickel. Even though the excitation pulse is incident from the Au side, we observe a very rapid heating of the Ni lattice, whereas the Au lattice initially remains cold. The subsequent heat transfer from Ni to the Au lattice is found to be two orders of magnitude slower than predicted by the conventional heat equation and much slower than electron-phonon coupling times in Au. We present a simplified model calculation highlighting the relevant thermophysical quantities.},
  language  = {en}
}
@misc{PudellMaznevHerzogetal.2018,
  author    = {Pudell, Jan-Etienne and Maznev, Alexei and Herzog, Marc and Kronseder, M. and Back, Christian and Malinowski, Gregory and von Reppert, Alexander and Bargheer, Matias},
  title     = {Layer specific observation of slow thermal equilibration in ultrathin metallic nanostructures by femtosecond X-ray diffraction},
  series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  number    = {797},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-42623},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-426233},
  pages     = {7},
  year      = {2018},
  abstract  = {Ultrafast heat transport in nanoscale metal multilayers is of great interest in the context of optically induced demagnetization, remagnetization and switching. If the penetration depth of light exceeds the bilayer thickness, layer-specific information is unavailable from optical probes. Femtosecond diffraction experiments provide unique experimental access to heat transport over single digit nanometer distances. Here, we investigate the structural response and the energy flow in the ultrathin double-layer system: gold on ferromagnetic nickel. Even though the excitation pulse is incident from the Au side, we observe a very rapid heating of the Ni lattice, whereas the Au lattice initially remains cold. The subsequent heat transfer from Ni to the Au lattice is found to be two orders of magnitude slower than predicted by the conventional heat equation and much slower than electron-phonon coupling times in Au. We present a simplified model calculation highlighting the relevant thermophysical quantities.},
  language  = {en}
}
@article{LiebigHenningSarhanetal.2018,
  author    = {Liebig, Ferenc and Henning, Ricky and Sarhan, Radwan Mohamed and Prietzel, Claudia Christina and Bargheer, Matias and Koetz, Joachim},
  title     = {A new route to gold nanoflowers},
  series = {Nanotechnology},
  volume    = {29},
  journal   = {Nanotechnology},
  number    = {18},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0957-4484},
  doi       = {10.1088/1361-6528/aaaffd},
  pages     = {8},
  year      = {2018},
  abstract  = {Catanionic vesicles spontaneously formed by mixing the anionic surfactant bis(2-ethylhexyl)sulfosuccinate sodium salt with the cationic surfactant cetyltrimethylammonium bromide were used as a reducing medium to produce gold clusters, which are embedded and well-ordered into the template phase. The gold clusters can be used as seeds in the growth process that follows by adding ascorbic acid as a mild reducing component. When the ascorbic acid was added very slowly in an ice bath round-edged gold nanoflowers were produced. When the same experiments were performed at room temperature in the presence of Ag+ ions, sharp-edged nanoflowers could be synthesized. The mechanism of nanoparticle formation can be understood to be a non-diffusion-limited Ostwald ripening process of preordered gold nanoparticles embedded in catanionic vesicle fragments. Surface-enhanced Raman scattering experiments show an excellent enhancement factor of 1.7 . 10(5) for the nanoflowers deposited on a silicon wafer.},
  language  = {en}
}