TY - JOUR A1 - Jordan, Thomas A1 - Fechler, Nina A1 - Xu, Jingsan A1 - Brenner, Thomas J. K. A1 - Antonietti, Markus A1 - Shalom, Menny T1 - "Caffeine Doping" of Carbon/Nitrogen-Based Organic Catalysts: Caffeine as a Supramolecular Edge Modifier for the Synthesis of Photoactive Carbon Nitride Tubes JF - ChemCatChem : heterogeneous & homogeneous & bio- & nano-catalysis ; a journal of ChemPubSoc Europe N2 - An alternative method for the structure tuning of carbon nitride materials by using a supramolecular approach in combination with caffeine as lining-agent is described. The self-assembly of the precursor complex consisting of melamine and cyanuric acid can be controlled by this doping molecule in terms of morphology, electronic, and photophysical properties. Caffeine is proposed to insert as an edge-molecule eventually leading to hollow tube-like carbon nitride structures with improved efficiency of charge formation. Compared to the bulk carbon nitride, the caffeine-doped analogue possesses a higher photocatalytic activity for the degradation of rhodamineB dye. Furthermore, this approach is also shown to be suitable for the modification of carbon nitride electrodes. KW - caffeine KW - carbon nitride KW - films KW - photocatalysis KW - supramolecular chemistry Y1 - 2015 U6 - https://doi.org/10.1002/cctc.201500343 SN - 1867-3880 SN - 1867-3899 VL - 7 IS - 18 SP - 2826 EP - 2830 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Liebig, Ferenc A1 - Sarhan, Radwan Mohamed A1 - Prietzel, Claudia Christina A1 - Reinecke, Antje A1 - Koetz, Joachim T1 - "Green" gold nanotriangles: synthesis, purification by polyelectrolyte/micelle depletion flocculation and performance in surface-enhanced Raman scattering JF - RSC Advances N2 - The aim of this study was to develop a one-step synthesis of gold nanotriangles (NTs) in the presence of mixed phospholipid vesicles followed by a separation process to isolate purified NTs. Negatively charged vesicles containing AOT and phospholipids, in the absence and presence of additional reducing agents (polyampholytes, polyanions or low molecular weight compounds), were used as a template phase to form anisotropic gold nanoparticles. Upon addition of the gold chloride solution, the nucleation process is initiated and both types of particles, i.e., isotropic spherical and anisotropic gold nanotriangles, are formed simultaneously. As it was not possible to produce monodisperse nanotriangles with such a one-step procedure, the anisotropic nanoparticles needed to be separated from the spherical ones. Therefore, a new type of separation procedure using combined polyelectrolyte/micelle depletion flocculation was successfully applied. As a result of the different purification steps, a green colored aqueous dispersion was obtained containing highly purified, well-defined negatively charged flat nanocrystals with a platelet thickness of 10 nm and an edge length of about 175 nm. The NTs produce promising results in surface-enhanced Raman scattering. Y1 - 2016 U6 - https://doi.org/10.1039/c6ra04808k SN - 2046-2069 VL - 6 SP - 33561 EP - 33568 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Mikelskis, Helmut A1 - Horn, Martin Erik T1 - "Holographie" als Thema im Physikunterricht Y1 - 2000 SN - 3-88064-294-X ER - TY - JOUR A1 - Chen, Zupeng A1 - Savateev, Aleksandr A1 - Pronkin, Sergey A1 - Papaefthimiou, Vasiliki A1 - Wolff, Christian Michael A1 - Willinger, Marc Georg A1 - Willinger, Elena A1 - Neher, Dieter A1 - Antonietti, Markus A1 - Dontsova, Dariya T1 - "The Easier the Better" Preparation of Efficient Photocatalysts-Metastable Poly(heptazine imide) Salts JF - Advanced materials N2 - Cost-efficient, visible-light-driven hydrogen production from water is an attractive potential source of clean, sustainable fuel. Here, it is shown that thermal solid state reactions of traditional carbon nitride precursors (cyanamide, melamine) with NaCl, KCl, or CsCl are a cheap and straightforward way to prepare poly(heptazine imide) alkali metal salts, whose thermodynamic stability decreases upon the increase of the metal atom size. The chemical structure of the prepared salts is confirmed by the results of X-ray photoelectron and infrared spectroscopies, powder X-ray diffraction and electron microscopy studies, and, in the case of sodium poly(heptazine imide), additionally by atomic pair distribution function analysis and 2D powder X-ray diffraction pattern simulations. In contrast, reactions with LiCl yield thermodynamically stable poly(triazine imides). Owing to the metastability and high structural order, the obtained heptazine imide salts are found to be highly active photo-catalysts in Rhodamine B and 4-chlorophenol degradation, and Pt-assisted sacrificial water reduction reactions under visible light irradiation. The measured hydrogen evolution rates are up to four times higher than those provided by a benchmark photocatalyst, mesoporous graphitic carbon nitride. Moreover, the products are able to photocatalytically reduce water with considerable reaction rates, even when glycerol is used as a sacrificial hole scavenger. KW - carbon nitride KW - glycerol oxidation KW - mesocrystals KW - poly(heptazine imide) KW - water reduction reactions Y1 - 2017 U6 - https://doi.org/10.1002/adma.201700555 SN - 0935-9648 SN - 1521-4095 VL - 29 SP - 21800 EP - 21806 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Henkel, Carsten A1 - Gardiner, Simon A. A1 - Negretti, Antonio T1 - (De)coherence physics with condensates in microtraps N2 - We discuss the dynamics of a condensate in a miniaturized electromagnetic trap formed above a microstructured substrate. Recent experiments have found that trap lifetimes get reduced when approaching the substrate because atoms couple to thermally excited near fields. The data agree quantitatively with our theory [Appl. Phys. B 69, 379 (1999)]. We focus on the decoherence of a quantum degenerate gas in a quasi-one-dimensional trap. Monte Carlo simulations indicate that atom interactions reduce the condensate decoherence rate. This is explained by a simple theory in terms of the suppression of long-wavelength excitations. We present preliminary simulation results for the adiabatic generation of dark solitons Y1 - 2004 SN - 1054-660X ER - TY - JOUR A1 - Pade, Sylvia A1 - Schmidt, Hartmut A1 - Stumpe, Joachim A1 - Fischer, Thomas M. T1 - (Micro-)fluorescence spectroscopy of side chain polymers with bezanilide moieties Y1 - 1996 ER - TY - JOUR A1 - Gardiner, Simon A. T1 - (Quantum) chaos in Bose-Einstein condensates Y1 - 2002 SN - 0950-0340 ER - TY - JOUR A1 - Mikat, Jürgen E. R. A1 - Franco, Olga A1 - Regenstein, Wolfgang A1 - Reck, Günter A1 - Knochenhauer, Gerald A1 - Schulz, Burkhard A1 - Orgzall, Ingo T1 - 1,3,4-oxadiazole crystals under high pressure-phase transitions and properties Y1 - 2000 ER - TY - JOUR A1 - Eichler, Hans Joachim A1 - Haase, Alfred A1 - Menzel, Ralf T1 - 100 watt average output power 1.2*diffraction limited beam from pulsed neodym single rod amplifier with SBS- phaseconjugation BT - Onehundred watt average output 1.2*diffraction limited beam from pulsed neodym single rod amplifier with SBS- phaseconjugation T2 - Hundred watt average output power 1.2*diffraction limited beam from pulsed neodym single rod amplfier with SBS- phaseconjugation Y1 - 1995 ER - TY - JOUR A1 - Schulze, Patricia S. C. A1 - Bett, Alexander J. A1 - Bivour, Martin A1 - Caprioglio, Pietro A1 - Gerspacher, Fabian M. A1 - Kabaklı, Özde Ş. A1 - Richter, Armin A1 - Stolterfoht, Martin A1 - Zhang, Qinxin A1 - Neher, Dieter A1 - Hermle, Martin A1 - Hillebrecht, Harald A1 - Glunz, Stefan W. A1 - Goldschmidt, Jan Christoph T1 - 25.1% high-efficiency monolithic perovskite silicon tandem solar cell with a high bandgap perovskite absorber JF - Solar RRL N2 - Monolithic perovskite silicon tandem solar cells can overcome the theoretical efficiency limit of silicon solar cells. This requires an optimum bandgap, high quantum efficiency, and high stability of the perovskite. Herein, a silicon heterojunction bottom cell is combined with a perovskite top cell, with an optimum bandgap of 1.68 eV in planar p-i-n tandem configuration. A methylammonium-free FA(0.75)Cs(0.25)Pb(I0.8Br0.2)(3) perovskite with high Cs content is investigated for improved stability. A 10% molarity increase to 1.1 m of the perovskite precursor solution results in approximate to 75 nm thicker absorber layers and 0.7 mA cm(-2) higher short-circuit current density. With the optimized absorber, tandem devices reach a high fill factor of 80% and up to 25.1% certified efficiency. The unencapsulated tandem device shows an efficiency improvement of 2.3% (absolute) over 5 months, showing the robustness of the absorber against degradation. Moreover, a photoluminescence quantum yield analysis reveals that with adapted charge transport materials and surface passivation, along with improved antireflection measures, the high bandgap perovskite absorber has the potential for 30% tandem efficiency in the near future. KW - heterojunction silicon solar cells KW - interfaces KW - perovskite solar cells KW - tandem solar cells KW - thin films Y1 - 2020 VL - 4 IS - 7 PB - John Wiley & Sons, Inc. CY - New Jersey ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Heuer, Axel A1 - Menzel, Ralf T1 - 27 Watt average output power with 1.2*DL beam quality from a single rod Nd:YAG-Laser with phase conjugating SBS- mirror BT - Siebenundzwanzig Watt average output power with 1.2*DL beam quality from a single rod Nd:YAG-Laser with phase conjugating SBS-mirror Y1 - 1998 ER - TY - JOUR A1 - Evans, Chris J. A1 - van Loon, Jacco Th. A1 - Hainich, Rainer A1 - Bailey, M. T1 - 2dF-AAOmega spectroscopy of massive stars in the Magellanic Clouds The north-eastern region of the Large Magellanic Cloud JF - Astronomy and astrophysics : an international weekly journal N2 - We present spectral classifications from optical spectroscopy of 263 massive stars in the north-eastern region of the Large Magellanic Cloud. The observed two-degree field includes the massive 30 Doradus star-forming region, the environs of SN1987A, and a number of star-forming complexes to the south of 30 Dor. These are the first classifications for the majority (203) of the stars and include eleven double-lined spectroscopic binaries. The sample also includes the first examples of early OC-type spectra (AA Omega 30 Dor 248 and 280), distinguished by the weakness of their nitrogen spectra and by C IV lambda 4658 emission. We propose that these stars have relatively unprocessed CNO abundances compared to morphologically normal O-type stars, indicative of an earlier evolutionary phase. From analysis of observations obtained on two consecutive nights, we present radial-velocity estimates for 233 stars, finding one apparent single-lined binary and nine (>3 sigma) outliers compared to the systemic velocity; the latter objects could be runaway stars or large-amplitude binary systems and further spectroscopy is required to investigate their nature. KW - Magellanic Clouds KW - stars: early-type KW - stars: fundamental parameters KW - open clusters and associations: general Y1 - 2015 U6 - https://doi.org/10.1051/0004-6361/201525882 SN - 1432-0746 VL - 584 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Menzel, Ralf T1 - 34 Watt flash lamp pumped single rod ND:YAG laser with 1.2 * DL beam quality via special resonator design BT - Vierunddreißig Watt flash lamp pumped single rod ND:YAG laser with 1.2 * DL beam quality via special resonator design Y1 - 1997 ER - TY - JOUR A1 - Pham, Cong Duc A1 - Petre, Anca A1 - Berquez, Laurent A1 - Flores Suárez, Rosaura A1 - Mellinger, Axel A1 - Wirges, Werner A1 - Gerhard, Reimund T1 - 3D high-resolution mapping of polarization profiles in thin poly(vinylidenefluoride-trifluoroethylene) (PVDF- TrFE) films using two thermal techniques N2 - In this paper, two non-destructive thermal methods are used in order to determine, with a high degree of accuracy, three-dimensional polarization distributions in thin films (12 mu m) of poly(vinylidenefluoride- trifluoroethylene) (PVDF-TrFE). The techniques are the frequency-domain Focused Laser Intensity Modulation Method (FLIMM) and time-domain Thermal-Pulse Tomography (TPT). Samples were first metalized with grid-shaped electrode and poled. 3D polarization mapping yielded profiles which reproduce the electrode-grid shape. The polarization is not uniform across the sample thickness. Significant polarization values are found only at depths beyond 0.5 mu m from the sample surface. Both methods provide similar results, TPT method being faster, whereas the FLIMM technique has a better lateral resolution. Y1 - 2009 UR - http://ieeexplore.ieee.org/servlet/opac?punumber=94 U6 - https://doi.org/10.1109/TDEI.2009.5128505 SN - 1070-9878 ER - TY - JOUR A1 - Madura, T. I. A1 - Clementel, N. A1 - Gull, T. R. A1 - Kruip, C. J. H. A1 - Paardekooper, J.-P. A1 - Icke, V. T1 - 3D hydrodynamical and radiative transfer modeling of η Carinae's colliding winds JF - Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015 N2 - We present results of full 3D hydrodynamical and radiative transfer simulations of the colliding stellar winds in the massive binary system η Carinae. We accomplish this by applying the SimpleX algorithm for 3D radiative transfer on an unstructured Voronoi-Delaunay grid to recent 3D smoothed particle hydrodynamics (SPH) simulations of the binary colliding winds. We use SimpleX to obtain detailed ionization fractions of hydrogen and helium, in 3D, at the resolution of the original SPH simulations. We investigate several computational domain sizes and Luminous Blue Variable primary star mass-loss rates. We furthermore present new methods of visualizing and interacting with output from complex 3D numerical simulations, including 3D interactive graphics and 3D printing. While we initially focus on η Car, the methods employed can be applied to numerous other colliding wind (WR 140, WR 137, WR 19) and dusty `pinwheel' (WR 104, WR 98a) binary systems. Coupled with 3D hydrodynamical simulations, SimpleX simulations have the potential to help determine the regions where various observed time-variable emission and absorption lines form in these unique objects. Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-87930 SP - 163 EP - 166 ER - TY - JOUR A1 - Reyes-Iturbide, J. A1 - Velázquez, Pablo F. A1 - Rosado, M. T1 - 3D numerical model for NGC 6888 Nebula JF - Wolf-Rayet Stars : Proceedings of an International Workshop held in Potsdam, Germany, 1.–5. June 2015 N2 - We present 3D numerical simulations of the NGC6888 nebula considering the proper motion and the evolution of the star, from the red supergiant (RSG) to the Wolf-Rayet (WR) phase. Our simulations reproduce the limb-brightened morphology observed in [OIII] and X-ray emission maps. The synthetic maps computed by the numerical simulations show filamentary and clumpy structures produced by instabilities triggered in the interaction between the WR wind and the RSG shell. Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-88485 SP - 363 ER - TY - JOUR A1 - Thompson, W. T. A1 - Kliem, Bernhard A1 - Toeroek, Tibor T1 - 3D reconstruction of a rotating erupting prominence JF - Solar physics : a journal for solar and solar-stellar research and the study of solar terrestrial physics N2 - A bright prominence associated with a coronal mass ejection (CME) was seen erupting from the Sun on 9 April 2008. This prominence was tracked by both the Solar Terrestrial Relations Observatory (STEREO) EUVI and COR1 telescopes, and was seen to rotate about the line of sight as it erupted; therefore, the event has been nicknamed the "Cartwheel CME." The threads of the prominence in the core of the CME quite clearly indicate the structure of a weakly to moderately twisted flux rope throughout the field of view, up to heliocentric heights of 4 solar radii. Although the STEREO separation was 48A degrees, it was possible to match some sharp features in the later part of the eruption as seen in the 304 line in EUVI and in the H alpha-sensitive bandpass of COR1 by both STEREO Ahead and Behind. These features could then be traced out in three-dimensional space, and reprojected into a view in which the eruption is directed toward the observer. The reconstructed view shows that the alignment of the prominence to the vertical axis rotates as it rises up to a leading-edge height of a parts per thousand aEuro parts per thousand 2.5 solar radii, and then remains approximately constant. The alignment at 2.5 solar radii differs by about 115A degrees from the original filament orientation inferred from H alpha and EUV data, and the height profile of the rotation, obtained here for the first time, shows that two thirds of the total rotation are reached within a parts per thousand aEuro parts per thousand 0.5 solar radii above the photosphere. These features are well reproduced by numerical simulations of an unstable moderately twisted flux rope embedded in external flux with a relatively strong shear field component. KW - Corona, active KW - Prominences, active KW - Coronal mass ejections KW - Initiation and propagation KW - Magnetic fields, corona Y1 - 2012 U6 - https://doi.org/10.1007/s11207-011-9868-5 SN - 0038-0938 VL - 276 IS - 1-2 SP - 241 EP - 259 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Ostermeyer, Martin A1 - Menzel, Ralf T1 - 50 Watt average output power with 1.2*DL beam quality from a single rod Nd:YALO laser with phase-conjugating SBS mirror BT - Fünfzig Watt average output power with 1.2*DL beam quality from a single rod Nd:YALO laser with phase- conjugating SBS mirror Y1 - 1999 ER - TY - JOUR A1 - Gerhard, Reimund T1 - 50 years of International Symposia on Electrets from 1967 to 2017 BT - a global history JF - IEEE electrical insulation magazine / Institute of Electrical and Electronics Engineers N2 - The prehistory of electrets is not known yet, but it is quite likely that the electrostatic charging behavior of amber (Greek: τò ηλεκτρoν, i.e., “electron”) already was familiar to people in ancient cultures (China, Egypt, Greece, etc.), before the Greek philosopher and scientist Thales of Miletus (6th century BCE)-or rather his disciples and followers-reported it in writing (cf. Figure 1). More than two millennia later, William Gilbert (1544–1603), the physician of Queen Elizabeth I, coined the term “electric” in his book De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure (1600) for dielectric materials that attract like amber and that included sulfur and glass [1]. The second half of the 18th century saw the invention of the electrophorus or electrophore [2], a capacitive electret device, in 1762 by Johan Carl Wilcke (1732–1796). Y1 - 2021 U6 - https://doi.org/10.1109/MEI.2021.9352710 SN - 0883-7554 SN - 1558-4402 VL - 37 IS - 2 SP - 50 EP - 55 PB - IEEE CY - New York, NY ER - TY - JOUR A1 - Koesterke, Lars A1 - Hamann, Wolf-Rainer T1 - [WC]-type CSPN : clumping and wind-driving N2 - Many Central Stars of Planetary Nebulae are very similar to massive Wolf-Rayet stars of the carbon sequence with respect to their spectra, chemical composition and wind properties. Therefore their study opens an additional way towards the understanding of the Wolf-Rayet phenomenon. While the study of Line Profile Variation will be difficult, espescially for the very compact early types, the comparision with other hydrogen-deficient Central Stars illuminates the driving mechanism of their winds. We speculate that at least two ingredients are needed. The ionization of their atmpospheres has to be stratified to enable multi-scattering processes and the amount of carbon and oxygen has to be high (more than a few percent by mass). Y1 - 2002 ER -