@misc{LomadzeKopyshevBargheeretal.2017, author = {Lomadze, Nino and Kopyshev, Alexey and Bargheer, Matias and Wollgarten, Markus and Santer, Svetlana}, title = {Mass production of polymer nanowires filled with metal nanoparticles}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-402712}, pages = {10}, year = {2017}, abstract = {Despite the ongoing progress in nanotechnology and its applications, the development of strategies for connecting nano-scale systems to micro- or macroscale elements is hampered by the lack of structural components that have both, nano- and macroscale dimensions. The production of nano-scale wires with macroscale length is one of the most interesting challenges here. There are a lot of strategies to fabricate long nanoscopic stripes made of metals, polymers or ceramics but none is suitable for mass production of ordered and dense arrangements of wires at large numbers. In this paper, we report on a technique for producing arrays of ordered, flexible and free-standing polymer nano-wires filled with different types of nano-particles. The process utilizes the strong response of photosensitive polymer brushes to irradiation with UV-interference patterns, resulting in a substantial mass redistribution of the polymer material along with local rupturing of polymer chains. The chains can wind up in wires of nano-scale thickness and a length of up to several centimeters. When dispersing nano-particles within the film, the final arrangement is similar to a core-shell geometry with mainly nano-particles found in the core region and the polymer forming a dielectric jacket.}, language = {en} } @misc{MatternPudellDumesniletal.2023, author = {Mattern, Maximilian and Pudell, Jan-Etienne and Dumesnil, Karine and Reppert, Alexander von and Bargheer, Matias}, title = {Towards shaping picosecond strain pulses via magnetostrictive transducers}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1321}, issn = {1866-8372}, doi = {10.25932/publishup-58886}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-588868}, pages = {7}, year = {2023}, abstract = {Using time-resolved x-ray diffraction, we demonstrate the manipulation of the picosecond strain response of a metallic heterostructure consisting of a dysprosium (Dy) transducer and a niobium (Nb) detection layer by an external magnetic field. We utilize the first-order ferromagnetic-antiferromagnetic phase transition of the Dy layer, which provides an additional large contractive stress upon laser excitation compared to its zerofield response. This enhances the laser-induced contraction of the transducer and changes the shape of the picosecond strain pulses driven in Dy and detected within the buried Nb layer. Based on our experiment with rare-earth metals we discuss required properties for functional transducers, which may allow for novel field-control of the emitted picosecond strain pulses.}, language = {en} } @misc{MatternPudellLaskinetal.2021, author = {Mattern, Maximilian and Pudell, Jan-Etienne and Laskin, G. and Reppert, Alexander von and Bargheer, Matias}, title = {Analysis of the temperature- and fluence-dependent magnetic stress in laser-excited SrRuO3}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, issn = {1866-8372}, doi = {10.25932/publishup-51571}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-515718}, pages = {11}, year = {2021}, abstract = {We use ultrafast x-ray diffraction to investigate the effect of expansive phononic and contractive magnetic stress driving the picosecond strain response of a metallic perovskite SrRuO3 thin film upon femtosecond laser excitation. We exemplify how the anisotropic bulk equilibrium thermal expansion can be used to predict the response of the thin film to ultrafast deposition of energy. It is key to consider that the laterally homogeneous laser excitation changes the strain response compared to the near-equilibrium thermal expansion because the balanced in-plane stresses suppress the Poisson stress on the picosecond timescale. We find a very large negative Gr{\"u}neisen constant describing the large contractive stress imposed by a small amount of energy in the spin system. The temperature and fluence dependence of the strain response for a double-pulse excitation scheme demonstrates the saturation of the magnetic stress in the high-fluence regime.}, language = {en} } @misc{MitzscherlingCuiKoopmanetal.2015, author = {Mitzscherling, Steffen and Cui, Qianling and Koopman, Wouter-Willem Adriaan and Bargheer, Matias}, title = {Dielectric function of two-phase colloid-polymer nanocomposite}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-102695}, pages = {29465 -- 29474}, year = {2015}, abstract = {The plasmon resonance of metal nanoparticles determines their optical response in the visible spectral range. Many details such as the electronic properties of gold near the particle surface and the local environment of the particles influence the spectra. We show how the cheap but highly precise fabrication of composite nanolayers by spin-assisted layer-by-layer deposition of polyelectrolytes can be used to investigate the spectral response of gold nanospheres (GNS) and gold nanorods (GNR) in a self-consistent way, using the established Maxwell-Garnett effective medium (MGEM) theory beyond the limit of homogeneous media. We show that the dielectric function of gold nanoparticles differs from the bulk value and experimentally characterize the shape and the surrounding of the particles thoroughly by SEM, AFM and ellipsometry. Averaging the dielectric functions of the layered surrounding by an appropriate weighting with the electric field intensity yields excellent agreement for the spectra of several nanoparticles and nanorods with various cover-layer thicknesses.}, language = {en} } @misc{PavlenkoSanderMitzscherlingetal.2016, author = {Pavlenko, Elena S. and Sander, Mathias and Mitzscherling, Steffen and Pudell, Jan-Etienne and Zamponi, Flavio and R{\"o}ssle, Matthias and Bojahr, Andre and Bargheer, Matias}, title = {Azobenzene - functionalized polyelectrolyte nanolayers as ultrafast optoacoustic transducers}, volume = {8}, doi = {10.1039/C6NR01448H}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-101996}, pages = {13297 -- 13302}, year = {2016}, abstract = {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.}, language = {en} } @misc{ReppertPuddellKocetal.2016, author = {Reppert, Alexander von and Puddell, J. and Koc, A. and Reinhardt, M. and Leitenberger, Wolfram and Dumesnil, K. and Zamponi, Flavio and Bargheer, Matias}, title = {Persistent nonequilibrium dynamics of the thermal energies in the spin and phonon systems of an antiferromagnet}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-98710}, pages = {11}, year = {2016}, abstract = {We present a temperature and fluence dependent Ultrafast X-Ray Diffraction study of a laser-heated antiferromagnetic dysprosium thin film. The loss of antiferromagnetic order is evidenced by a pronounced lattice contraction. We devise a method to determine the energy flow between the phonon and spin system from calibrated Bragg peak positions in thermal equilibrium. Reestablishing the magnetic order is much slower than the cooling of the lattice, especially around the N{\´e}el temperature. Despite the pronounced magnetostriction, the transfer of energy from the spin system to the phonons in Dy is slow after the spin-order is lost.}, 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} } @misc{ZeuschnerMatternPudelletal.2021, author = {Zeuschner, Steffen Peer and Mattern, Maximilian and Pudell, Jan-Etienne and Reppert, Alexander von and R{\"o}ssle, Matthias and Leitenberger, Wolfram and Schwarzkopf, Jutta and Boschker, Jos and Herzog, Marc and Bargheer, Matias}, title = {Reciprocal space slicing}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1137}, issn = {1866-8372}, doi = {10.25932/publishup-49976}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-499761}, pages = {13}, year = {2021}, abstract = {An experimental technique that allows faster assessment of out-of-plane strain dynamics of thin film heterostructures via x-ray diffraction is presented. In contrast to conventional high-speed reciprocal space-mapping setups, our approach reduces the measurement time drastically due to a fixed measurement geometry with a position-sensitive detector. This means that neither the incident (ω) nor the exit (2θ) diffraction angle is scanned during the strain assessment via x-ray diffraction. Shifts of diffraction peaks on the fixed x-ray area detector originate from an out-of-plane strain within the sample. Quantitative strain assessment requires the determination of a factor relating the observed shift to the change in the reciprocal lattice vector. The factor depends only on the widths of the peak along certain directions in reciprocal space, the diffraction angle of the studied reflection, and the resolution of the instrumental setup. We provide a full theoretical explanation and exemplify the concept with picosecond strain dynamics of a thin layer of NbO2.}, language = {en} }