TY - CONF A1 - Bonse, Jörn T1 - Laser-Induced Periodic Surface Structures: when Maxwell meets Marangoni N2 - Laser-Induced Periodic Surface Structures (LIPSS, ripples) are a universal phenomenon and can be generated in a contactless, single-step process on almost any material upon irradiation of solids with intense laser radiation. Nowadays, processing rates of up to m^2/min are enabling new industrial applications in medicine, optics, tribology, biology, etc. Depending on the specific type of LIPSS, their structural sizes typically range from several micrometers down to less than 100 nanometers – far beyond the optical diffraction limit – while their orientations exhibit a clear correlation with the local polarization direction of the laser radiation. From a theoretical point of view, however, a controversial and vivid debate has emerged during the last two decades, whether LIPSS originate from electromagnetic effects (seeded already during the laser irradiation) – or whether they emerge from matter reorganization processes, i.e. distinctly after the laser irradiation. This presentation reviews the currently existent theories of LIPSS. A focus is laid on the historic development of the fundamental ideas, their corresponding mathematical descriptions and numerical implementations, along with a comparison and critical assessment of the different approaches. T2 - 16th International Conference on Laser Ablation (COLA 2021/22) CY - Matsue, Japan DA - 24.04.2022 KW - Laser-induced periodic surface structures (LIPSS) KW - Laser ablation KW - Theoretical modelling KW - Electromagnetic scattering KW - Hydrodynamics PY - 2022 AN - OPUS4-54716 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kolmangadi, Mohamed Aejaz T1 - Side Chain length dependent dynamics and conductivity of Ionic Liquid crystals N2 - We investigate the molecular dynamics and electrical conductivity for a homologous series of linear shaped guanidinium based cyclic ILCs that vary in alkyl chain length, CLCRs (R = 8, 10, 12, 14, 16) by employing broadband dielectric spectroscopy (BDS), and calorimetry comprised of Fast Scanning Calorimetry (FSC) and temperature modulated FSC (TMFSC). Besides conductivity at high temperatures, the dielectric dispersion reveals two relaxation modes: the fast γ and the slow α1 relaxation. The former is assigned to the localized fluctuations while the latter is due to segmental dynamics of the alkyl chains. The γ mode slows down for long chain length CLCs (12,14,16) compared to their shorter analogues. Calorimetric investigation reveals one process, the α2 process, for all ILCs. The α2 process for CLC10, 12, and 14 has a similar temperature dependence as the dielectric α1 relaxation, while for the CLC8 and 10, it's shifted to a higher temperature. For all CLCRs, the absolute values of DC conductivity increase by 4 orders of magnitude at the transition from the plastic crystalline to hexagonal columnar phase. This increase is due to the change in the underlying conduction mechanism from delocalized electron hopping in the crystalline phase to one-dimensional ion mobility in the columnar phase. The glassy dynamics shifts to higher temperatures with increasing alkyl chain length. Conversely, the DC conductivity drops by 3 orders of magnitude from CLC8 to CLC16. T2 - APS March Meeting 2022 CY - Chicago, IL, USA DA - 13.03.2022 KW - Glass transition KW - Conductivity KW - Fast Scanning Calorimetry KW - Dynamics PY - 2022 AN - OPUS4-54760 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kuchenbecker, Petra T1 - Bestimmung der Partikelgrößenverteilung mittels Zentrifugen-Sedimentationsverfahren nach ISO 13318-2 (Küvette) N2 - Im Vortrag werden das Messprinzip des Zentrifugen-Sedimentationsverfahrens erläutert und die Anforderungen der zugrundeliegenden Normen diskutiert. Es schließen sich umfangreiche Ausführungen zur praktischen Durchführung der Messung, insbesondere auch zu den vorbereitenden Arbeiten, sowie zur Auswertung der Rohdaten an. Gezeigt werden die Validierung sowie ein Beispiel zur regelmäßigen Verifizierung des Verfahrens. Nach Beispielen und Vergleichen zu Ergebnissen mit anderen Messverfahren, wird das Verfahren in einer Zusammenfassung bewertet. T2 - Seminar Rheologie und Stabilität von dispersen Systemen CY - Potsdam, Germany DA - 09.05.2022 KW - Nano powder KW - Cetrifugal Liquid Sedimentation CLS KW - Particle size determination PY - 2022 AN - OPUS4-54863 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Deumer, J. A1 - Pauw, Brian Richard A1 - Marguet, S. A1 - Skroblin, D. A1 - Taché, O. A1 - Krumrey, M. A1 - Gollwitzer, C. T1 - Small-angle X-ray scattering: characterization of cubic Au nanoparticles using Debye’s scattering formula N2 - A versatile software package in the form of a Python extension, named CDEF (computing Debye’s scattering formula for extraordinary form factors), is proposed to calculate approximate scattering profiles of arbitrarily shaped nanoparticles for small-angle X-ray scattering (SAXS). CDEF generates a quasi-randomly distributed point cloud in the desired particle shape and then applies the open-source software DEBYER for efficient evaluation of Debye’s scattering formula to calculate the SAXS pattern (https://github.com/j-from-b/CDEF). If self-correlation of the scattering signal is not omitted, the quasi-random distribution provides faster convergence compared with a true-random distribution of the scatterers, especially at higher momentum transfer. The usage of the software is demonstrated for the evaluation of scattering data of Au nanocubes with rounded edges, which were measured at the four-crystal monochromator beamline of PTB at the synchrotron radiation facility BESSY II in Berlin. The implementation is fast enough to run on a single desktop computer and perform model fits within minutes. The accuracy of the method was analyzed by comparison with analytically known form factors and verified with another implementation, the SPONGE, based on a similar principle with fewer approximations. Additionally, the SPONGE coupled to McSAS3 allows one to retrieve information on the uncertainty of the size distribution using a Monte Carlo uncertainty estimation algorithm. KW - X-ray scattering KW - SAXS KW - Non-spherical nanoparticles KW - Nanoparticles KW - Nanomaterials KW - Debye scattering equation KW - Simulation KW - Data fitting PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-557652 DO - https://doi.org/10.1107/S160057672200499X VL - 55 IS - Pt 4 SP - 993 EP - 1001 PB - International Union of Crystallography CY - Chester, England AN - OPUS4-55765 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Laser-induced Periodic Surface Structures (LIPSS): Mechanisms, Applications, and unsolved Problems N2 - Laser-induced Periodic Surface Structures (LIPSS, ripples) are a universal phenomenon and can be generated in a contactless, single-step process on almost any type of solid upon irradiation with intense laser pulses. They represent a (quasi-)periodic modulation of the surface topography in the form of a linear grating and are typically formed in a “self-ordered” way in the focus of a laser beam. Thus, they are often accompanying laser material processing applications. The structural sizes of LIPSS typically range from several micrometers down to less than 100 nanometers – far beyond the optical diffraction limit – while their orientations exhibit a clear correlation with the local polarization direction of the laser radiation. From a theoretical point of view, a controversial debate has emerged during the last decades, whether LIPSS originate from electromagnetic effects (seeded already during the laser irradiation) – or whether they emerge from matter-reorganization processes (distinctly after the laser irradiation). From a practical point of view, however, LIPSS represent a simple and robust way for the nanostructuring of solids that allows creating a wide range of different surface functionalities featuring applications in optics, tribology, medicine, energy technologies, etc. While the currently available laser and scanner technology already allows surface processing rates at the m^2/min level, industrial applications of LIPSS are sometimes limited by the complex interplay between the nanoscale surface topography and the specific surface chemistry. This typically manifests in difficulties to control the processing of LIPSS and in limitations to ensure the long-term stability of the created surface functions. This presentation reviews the currently existent theories of LIPSS. A focus is laid on the historic development of the fundamental ideas behind the LIPSS, their corresponding mathematical descriptions and numerical implementations, along with a comparison and critical assessment of the different approaches. Moreover, some unsolved scientific problems related to LIPSS are identified and the pending technological limitations are discussed. Hereby, it is intended to stimulate further research and developments in the field of LIPSS for overcoming these limitations and for supporting the transfer of the LIPSS technology into industry T2 - 10th International LIPSS Workshop 2022 CY - Orléans, France DA - 21.09.2022 KW - Laser-induced periodic surface structures (LIPSS) KW - Surface functionalization KW - Femtosecond laser processing KW - Time-resolved coherent scattering PY - 2022 AN - OPUS4-55814 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chambers, M. S. A1 - Hunter, R. D. A1 - Hollamby, M. J. A1 - Pauw, Brian Richard A1 - Smith, A. J. A1 - Snow, T. A1 - Danks, A. E. A1 - Schnepp, Z. T1 - In Situ and Ex Situ X‑ray Diffraction and Small-Angle X‑ray Scattering Investigations of the Sol−Gel Synthesis of Fe3N and Fe3C N2 - Iron nitride (Fe3N) and iron carbide (Fe3C) nanoparticles can be prepared via sol−gel synthesis. While sol−gel methods are simple, it can be difficult to control the crystalline composition, i.e., to achieve a Rietveld-pure product. In a previous in situ synchrotron study of the sol−gel synthesis of Fe3N/Fe3C, we showed that the reaction proceeds as follows: Fe3O4 → FeOx → Fe3N → Fe3C. There was considerable overlap between the different phases, but we were unable to ascertain whether this was due to the experimental setup (side-on heating of a quartz capillary which could lead to thermal gradients) or whether individual particle reactions proceed at different rates. In this paper, we use in situ wide- and small-angle X-ray scattering (wide-angle X-ray scattering (WAXS) and small-angle X-ray scattering (SAXS)) to demonstrate that the overlapping phases are indeed due to variable reaction rates. While the initial oxide nanoparticles have a small range of diameters, the size range expands considerably and very rapidly during the oxide−nitride transition. This has implications for the isolation of Rietveld-pure Fe3N, and in an extensive laboratory study, we were indeed unable to isolate phasepure Fe3N. However, we made the surprising discovery that Rietveld-pure Fe3C nanoparticles can be produced at 500 °C with a sufficient furnace dwell time. This is considerably lower than the previous reports of the sol−gel synthesis of Fe3C nanoparticles. KW - Small-angle X-ray Scattering KW - SAXS KW - Diffraction KW - XRD KW - Scattering KW - Sol-gel KW - Iron nitride KW - Nanoparticles KW - Iron carbide KW - Catalyst KW - In-situ KW - Ex-situ KW - Synthesis KW - Synchrotron PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-548226 DO - https://doi.org/10.1021/acs.inorgchem.1c03442 VL - 61 IS - 18 SP - 6742 EP - 6749 PB - ACS Publications CY - Washington AN - OPUS4-54822 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Szymoniak, Paulina A1 - Omar, Hassan A1 - Gawek, Marcel A1 - Hertwik, Andreas A1 - Madkour, Sherif A1 - Schönhals, Andreas T1 - Investigation of the behavior of thin polymeric films including the adsorbed layer on the substrate by nano-sized relaxation spectroscopy and complementary methods N2 - Thin polymeric films are of great importance of high number of high-tech applications for instance in sensors and nanoelectronics. Form the scientific point of view thin films with thickness below 100 nm are ideal model systems to study confinement effects on its properties for instance on the molecular relaxation processes. In this contribution an overview is presented about the behavior of different systems as investigated by nanosized relaxation spectroscopy like broadband dielectric spectroscopy employing nano structured capacitors and AC chip calorimetry complimented by ellipsometry. The systems considered are PVME1, PVME/PS blends2,3 P2VP4, PBAC5 and polysulfone6. Besides the film also the adsorbed layer on the substrate prepared by a leaching approach and investigated by AFM is considered.1,4-7. For these investigationsss it is found that the adsorbed layer itself exhibits a relaxation dynamics which might be assigned either to molecular motions or to adsorptions desorption kinetics. T2 - 9. International Discussion Meeting Relaxation Complex Systems CY - Chiba, Japan DA - 12.08.2023 KW - Thin polymer films PY - 2023 AN - OPUS4-58103 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Pauw, Brian Richard T1 - The SPONGE v.1.0.0: Modeling scattering of shapes by STL input, with absolute intensities and size distribution. N2 - Simulates X-ray and Neutron scattering patterns from arbitrary shapes defined by STL files. Features: - Uses multithreading to compute a number of independent solutions, then uses the variance of the results to estimate an uncertainty on the output. - Can be launched from the command line using an excel sheet to define settings, or from a jupyter notebook. - Outputs scattering patterns in absolute units if the contrast is set. - A Gaussian size distribution is available, where the relative scaling of objects for each repetion can be varied. Recommended to be used with limited width (max. 10%) to avoid artefacts. - Writes results with settings to an archival HDF5 file. Application examples: This software has been used in several studies to date. For example, it has been used here to simulate a model scattering pattern for a cuboid shape, which was then fed forward into the McSAS3 analysis program for analyzing scattering patterns of polydisperse cuboids. A second use is here, where it was used for the modeling of flattened helices. In this paper, scattering pattern features could be matched with particular morphological changes in the structure. Lastly, this paper has an example where it was used to validate the analytical analysis model, and explore the realistic limits of application of the analytical model. KW - Software KW - Scattering pattern analysis KW - Scattering pattern simulation KW - X-ray KW - Neutron KW - Command-line interface KW - Scattering pattern KW - STL file input KW - Python KW - Arbitrary shapes PY - 2023 DO - https://doi.org/10.6084/m9.figshare.21857130.v1 PB - Digital Science CY - Cambridge, MA, USA AN - OPUS4-56815 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hahn, Marc Benjamin T1 - Accessing radiation damage to biomolecules on the nanoscale by particle-scattering simulations N2 - Radiation damage to DNA plays a central role in radiation therapy to cure cancer. The physico-chemical and biological processes involved encompass huge time and spatial scales. To obtain a comprehensive understanding on the nano and the macro scale is a very challenging tasks for experimental techniques alone. Therefore particle-scattering simulations are often applied to complement measurements and aide their interpretation, to help in the planning of experiments, to predict their outcome and to test damage models. In the last years, powerful multipurpose particle-scattering framework based on the Monte-Carlo simulation (MCS) method, such as Geant4 and Geant4-DNA, were extended by user friendly interfaces such as TOPAS and TOPAS-nBio. This shifts their applicability from the realm of dedicated specialists to a broader range of scientists. In the present review we aim to give an overview over MCS based approaches to understand radiation interaction on a broad scale, ranging from cancerous tissue, cells and their organelles including the nucleus, mitochondria and membranes, over radiosensitizer such as metallic nanoparticles, and water with additional radical scavenger, down to isolated biomolecules in the form of DNA, RNA, proteins and DNA-protein complexes. Hereby the degradation of biomolecules by direct damage from inelastic scattering processes during the physical stage, and the indirect damage caused by radicals during the chemical stage as well as some parts of the early biological response is covered. Due to their high abundance the action of hydroxyl radicals (•OH) and secondary low energy electrons (LEE) as well as prehydrated electrons are covered in additional detail. Applications in the prediction of DNA damage, DNA repair processes, cell survival and apoptosis, influence of radiosensitizer on the dose distribution within cells and their organelles, the study of linear energy transfer (LET), the relative biological effectiveness (RBE), ion beam cancer therapy, microbeam radiation therapy (MRT), the FLASH effect, and the radiation induced bystander effect are reviewed. KW - DNA KW - Protein KW - G5P KW - OH KW - Au KW - AuNP KW - Radiation KW - SSB KW - DSB KW - Beta decay KW - Brachytherapy KW - Cancer treatment KW - Clustered nanoparticles KW - DNA damage KW - Dosimetry KW - Energy deposit KW - Geant4 KW - Geant4-DNA KW - Gold Nanoparticles KW - Livermore model KW - Low energy electrons KW - MCS KW - Microdosimetry KW - Monte-Carlo simulation KW - NP KW - OH radical KW - Particle scattering KW - Penelope model KW - Proteins KW - Radiation damage KW - Radiation therapy KW - Radiationtherapy KW - Radioactive decay KW - Radiolysis KW - Radiotherapy KW - Simulation KW - TOPAS KW - TOPAS-nbio KW - Base damage KW - Base loss KW - DNA radiation damage KW - Direct damage KW - Dissociative electron attachment (DEA) KW - Dissociative electron transfer (DET) KW - Double-strand break (DSB) KW - ESCA KW - Hydrated DNA KW - Hydrated electron KW - Hydration shell KW - Hydroxyl radical KW - Indirect damage KW - Ionization KW - Ionisation KW - NAP-XPS KW - Near ambient pressure xray photo electron spectroscopy KW - Net-ionization reaction KW - Prehydrated electron KW - Presolvated electron KW - Quasi-direct damage KW - ROS KW - Radical KW - Reactive oxygen species KW - Single-strand break (SSB) KW - XPS KW - Xray KW - Xray photo electron spectrocopy KW - Cosolute KW - Ectoin KW - Ectoine KW - GVP KW - Gene five protein KW - Hydroxyectoine KW - Ionizing radiation damage KW - OH radical scavenger KW - Monte-Carlo simulations KW - Nanodosimetry KW - Osmolyte KW - Particle scattering simulations KW - Protein unfolding KW - Radical Scavenge KW - Radical scavenger KW - Single-stranded DNA-binding proteins KW - SAXS KW - Bio-SAXS KW - X-ray scattering KW - ssDNA KW - dsDNA KW - FLASH effect KW - Bystander effect KW - Ion beam therapy KW - Bragg peak KW - LET KW - MCNP KW - Photons KW - Electrons KW - Carbon ions KW - MRT KW - RNA KW - RBE KW - base loss KW - abasic side KW - DMSO KW - Cells PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-573240 DO - https://doi.org/10.1088/2399-6528/accb3f SN - 2399-6528 VL - 7 IS - 4 SP - 042001 PB - Institute of Physics (IOP) Publishing CY - London AN - OPUS4-57324 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kolmangadi, Mohamed Aejaz T1 - Suppressed Transition and Dynamic self-asembly of ionic superdiscs in cylindrical nanochannels N2 - Liquid crystalline mesophases in nanoconfinement exhibit intriguing phase transition behaviors and relaxation dynamics. Here, we investigate the molecular mobility and electrical conductivity of a columnar ionic liquid crystal confined in self-ordered nanoporous alumina oxide membranes of pore size ranging from 180 nm down to 25 nm. We use nano-broadband dielectric spectroscopy (BDS) and calorimetry to study the dynamics and phase behavior. Calorimetric investigation reveals a complete suppression of the columnar – isotropic transition, while the plastic crystalline – columnar transition temperature decreases with inverse pore size and deviates from the Gibbs – Thomson equation. For the bulk case, BDS detects two relaxation modes in the crystalline phase, the γ relaxation and the α1 relaxation, and two relaxation modes in the columnar phase, the α2 and α3 relaxation. All relaxation modes slow down for the confined case compared to the bulk. However, a new relaxation mode reflecting the interfacial layer emerges for the 80 and 25 nm. We discuss the possible molecular origins of the different relaxation modes observed. For the bulk ILC, a clear jump of 4 orders of magnitude in the absolute values of DC conductivity occurs at the transition from the plastic crystalline to hexagonal columnar phase, for the confined ILC, this transition is smooth. DC conductivity is reduced for the confined case, except for the 25nm, where the values are similar to the bulk. T2 - APS March Meeting 2023 CY - Las Vegas, NV, USA DA - 05.03.2023 KW - Ionic Liquid crystals KW - Nanoconfinement KW - Conductivity PY - 2023 AN - OPUS4-57342 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krauss, S. W. A1 - Eckardt, M. A1 - Will, J. A1 - Spiecker, E. A1 - Siegel, R. A1 - Dulle, M. A1 - Schweins, R. A1 - Pauw, Brian Richard A1 - Senker, J. A1 - Zobel, M. T1 - H-D-isotope effect of heavy water affecting ligand-mediated nanoparticle formation in SANS and NMR experiments N2 - An isotopic effect of normal (H2O) vs. heavy water (D2O) is well known to fundamentally affect structure and chemical properties of proteins, for instance. Here we correlate results from small angle X-ray and neutron scattering (SAXS, SANS) with high-resolution scanning transmission electron microscopy to track the evolution of CdS nanoparticle size and crystallinity from aqeuous solution in presence of the organic ligand ethylenediaminetetraacetate (EDTA) at room temperature in both H2O and D2O. We provide evidence via SANS experiments that exchanging H2O by D2O impacts nanoparticle formation by changing the equilibria and dynamics of EDTA clusters in solution as investigated by nuclear magnetic resonance. The colloidal stability of the CdS nanoparticles, covered by a layer of [Cd(EDTA)]2- complexes, is significantly reduced in D2O despite the strong stabilizing effect of EDTA in suspensions of normal water. Hence, conclusions about nanoparticle formation mechanisms from D2O solutions can bare limited transferability to reactions in normal water due to isotopic effects, which thus need to be discussed for contrast match experiments. KW - General Materials Science KW - Quantum dots KW - CdS KW - Deuterium KW - X-ray scattering KW - MOUSE PY - 2023 DO - https://doi.org/10.1039/D3NR02419A SN - 2040-3364 VL - 15 IS - 40 SP - 16413 EP - 16424 PB - Royal Society of Chemistry (RSC) AN - OPUS4-58294 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Sokolowski‐Tinten, Klaus T1 - Probing Laser‐Driven Structure Formation at Extreme Scales in Space and Time N2 - Irradiation of solid surfaces with high intensity, ultrashort laser pulses triggers a variety of secondary processes that can lead to the formation of transient and permanent structures over a large range of length scales from mm down to the nano‐range. One of the most prominent examples are LIPSS – Laser‐Induced Periodic Surface Structures. While LIPSS have been a scientific evergreen for of almost 60 years, experimental methods that combine ultrafast temporal with the required nm spatial resolution have become available only recently with the advent of short pulse, short wavelength free electron lasers. Here, the current status and future perspectives in this field are discussed by exploiting the unique possibilities of these 4th‐generation light sources to address by time‐domain experimental techniques the fundamental LIPSS‐question, namely why and how laser irradiation can initiate the transition of a “chaotic” (rough) surface from an aperiodic into a periodic structure. KW - Laser-induced periodic surface structures (LIPSS) KW - Free electron laser KW - Pump-probe experiments KW - Time-resolved scattering KW - Capillary waves PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595048 DO - https://doi.org/10.1002/lpor.202300912 SN - 1863-8899 VL - 18 SP - 1 EP - 11 PB - Wiley-VCH GmbH CY - Weinheim AN - OPUS4-59504 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pauw, Brian Richard T1 - Everything SAXS Part 1: Introduction, Sample Requirements and Measurement "Space" N2 - This talk for the Swiss Society for Crystallography (SSCr) workshop on SAXS will introduce scattering from various angles, focusing in particular on: - Information content of X-ray scattering experiments, three entry points… - An introduction to Fourier Transforms - Sample criteria, compatibility, and selection - Key indicators of a measurement – where is the information? - Key indicators of measurement quality - Experiment planning, the basics T2 - Topical workshop of the Swiss Society for Crystallography CY - Zurich, Switzerland DA - 08.09.2023 KW - X-ray scattering KW - Data stewardship KW - Measurement science KW - MOUSE KW - Holistic experiment approaches PY - 2023 AN - OPUS4-58235 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pauw, Brian Richard T1 - Everything SAXS Part 2: Data Processing, Workflow and Pitfalls N2 - The second talk for the Swiss Society for Crystallography (SSCr) workshop on SAXS will highlight the data processing challenges, holistic experimental workflow developments, and the pitfalls. In particular, the following items will be addressed: - The importance of data processing and estimating uncertainty - A universal correction pipeline – away with the headaches, at least for this step! - Experiment planning part 2, some tips and advice to improve your corrected data. - Sample preparation, background selection, some tips and advice to improve your corrected data. - Automate for your mental well-being; electronic logbooks, measurement catalogs and workflow management software - Life on the edge: several pitfalls to avoid… T2 - Topical workshop of the Swiss Society for Crystallography CY - Zurich, Switzerland DA - 08.09.2023 KW - X-ray scattering KW - MOUSE KW - Data processing KW - Uncertainties KW - Pitfalls PY - 2023 AN - OPUS4-58236 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Pauw, Brian Richard T1 - Trinamic TMCL IOC for exposing Trinamics motor controllers to EPICS CA N2 - Trinamic TMCL IOC is a Python package designed for controlling stepper motors connected to a Trinamic board using the TMCL language (all boards supported by PyTrinamic should now work, has been tested on the TMCM 6110 and the TMCM 6214). Since it is implementing the TMCL protocol, it should be easy to adapt to other Trinamic motor controller boards. This package assumes the motor controller is connected over a machine network via a network-to-serial converter, but the underlying PyTrinamic package allows for other connections too. This allows the control of attached motors via the EPICS Channel-Access virtual communications bus. If EPICS is not desired, plain Pythonic control via motion_control should also be possible. An example for this will be provided in the example.ipynb Jupyter notebook. This package leverages Caproto for EPICS IOCs and a modified PyTrinamic library for the motor board control, and interfaces between the two via an internal set of dataclasses. Configuration for the motors and boards are loaded from YAML files (see tests/testdata/example_config.yaml). The modifications to PyTrinamic involved extending their library with a socket interface. This was a minor modification that should eventually find its way into the official package (a pull request has been submitted). KW - Instrumentation KW - Motor controller KW - EPICS KW - Channel access KW - Instrument control KW - Laboratory automation PY - 2024 DO - https://doi.org/10.5281/zenodo.10792593 PB - Zenodo CY - Geneva AN - OPUS4-59624 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ermilova, Elena T1 - Imaging spectroscopic ellipsometry for investigation of energy materials and materials for nano-electronics N2 - Ellipsometry is a very powerful tool used for accurate material investigation in a wide wavelength range. It is a non-destructive and fast method. Imaging ellipsometry as a combination of optical microscopy and ellipsometry enables spatially resolved measurements when determining the layer thickness and dielectric properties of thin layers. It is known for its high polarisation sensitivity and high contrast for the surface structures. In this contribution we show the application of the imaging ellipsometry for detection of defects in energy materials and quality validation of possible reference materials for nano-electronics. Defects in wide bandgap semiconductors, in homoepitaxial SiC and heteroepitaxial GaN layers on transparent SiC substrates, can be successfully detected and classified by means of imaging ellipsometry. Correlation of imaging ellipsometry results with results from complementary techniques such as white light interference microscopy as well as atomic force microscopy contribute to understanding of surface topography and defect formation mechanisms. We discuss the potential of different methods for analysing ellipsometric map data for monitoring the defect densities. Electric properties of materials at the nanoscale can be investigated by means of scanning probe microscopy methods such as scanning microwave microscopy and conductive atomic force microscopy. However, development of new robust and easy-to-use calibration methods and calibration standards is essential to increase the traceability of these methods and allow their broad application in industry. We show how imaging spectroscopic ellipsometry can be used for development and monitoring of processing quality of patterned reference samples based on indium tin oxide (ITO) layer with different thickness and conductivity. T2 - 12th Workshop on Spectroscopic Ellipsometry (WSE) CY - Prague, Czech Republic DA - 18.09.2023 KW - Ellipsometry KW - Thin Films KW - Transparent Conductive Oxides KW - Energy materials KW - White light interference microscopy KW - Nanoelectronics KW - Wide-bandgap semiconductors PY - 2023 AN - OPUS4-59340 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ayerdi Gomez, A. A1 - Slachciak, Nadine A1 - Zubia Aranburu, J. A1 - Zabala, A. A1 - Aginagalde, A. A1 - Bonse, Jörn A1 - Spaltmann, Dirk T1 - Improvement of the tribological performance of titanium alloy using FS-laser-induced periodic surface structures in combination with ZDDP and ionic liquid lubricant additives N2 - The performance of titanium alloy (Ti6Al4V) surfaces was investigated in lubricated reciprocating sliding tribological tests (RSTT). Special emphasis was laid on the effect of surface nanostructures in area of contact on the respective friction and wear behaviour. These so-called laser-induced periodic surface structures (LIPSS, ripples) were produced on the titanium alloy surface upon scan processing in air by an ultrashort pulsed femtosecond (fs) laser. As lubricant served two types of base oils, a pure polyalcylene-glycol, and an SAE 0W30 oil containing only antioxidants and temperature stabilizers. Tribological tests were carried out on polished as well as LIPSS covered areas using both types of base oil. A test metrics was established, combining the additive 2-ethylhexyl-zincdithiophosphate (ZDDP) or the ionic liquid [P6,6,6,14] [DEHP] (98% purity) with the respective base oils. The test metrics also considered the orientation of motion with respect to the orientation of the structures formed on the surface. Results are presented which show that the interplay between LIPSS and the local chemistry formed by the respective additives is beneficial for the tribological behaviour of the titanium alloy. Certain combinations of base oil, additive and LIPSS reduced friction and wear significantly in the tribological contact. T2 - 64. Tribologie-Fachtagung CY - Göttingen, Germany DA - 25.09.2023 KW - TiAl64V KW - 100Cr6 KW - Friction KW - Wear KW - LIPSS KW - Lubrication KW - PAG KW - Ionic liquid PY - 2023 SP - 1 EP - 5 AN - OPUS4-58642 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Laser-induced periodic surface structures: mechanisms, applications, and unsolved problems N2 - Laser-induced Periodic Surface Structures (LIPSS, ripples) are a universal phenomenon and can be generated in a contactless, single-step process on almost any type of solid upon irradiation with intense laser pulses. They represent a (quasi-)periodic modulation of the surface topography in the form of a linear grating and are typically formed in a “self-ordered” way in the focus of a laser beam. Thus, they are often accompanying laser material processing applications. The structural sizes of LIPSS typically range from several micrometers down to less than 100 nanometers – far beyond the optical diffraction limit – while their orientations exhibit a clear correlation with the local polarization direction of the laser radiation. From a theoretical point of view, a controversial debate has emerged during the last decades, whether LIPSS originate from electromagnetic effects (seeded already during the laser irradiation) – or whether they emerge from matter-reorganization processes (distinctly after the laser irradiation). From a practical point of view, however, LIPSS represent a simple and robust way for the nanostructuring of solids that allows creating a wide range of different surface functionalities featuring applications in optics, tribology, medicine, energy technologies, etc. This presentation reviews the currently existent theories of LIPSS. A focus is laid on the historic development of the fundamental ideas behind the LIPSS, their corresponding mathematical descriptions and numerical implementations, along with a comparison and critical assessment of the different approaches. Fourth generation light sources, namely short wavelength, short pulse free electron lasers (FELs) are offering new and fascinating possibilities to resolve laser-induced structure formation at surfaces on the sub-micrometer to nanometer length scale and in temporal regimes ranging from picoseconds to several nanoseconds with sub-picosecond resolution. This unique spatio-temporal resolution allows to reveal early signatures of coherent/plasmonic electromagnetic scattering effects followed by the excitation of hydrodynamic capillary waves – providing new insights to the above-mentioned debate. Finally, some unsolved scientific problems related to LIPSS are identified and the pending technological limitations are discussed. While the currently available laser and scanner technology already allows large area surface processing with rates at the m2/min level, industrial applications of LIPSS are sometimes limited by the complex interplay between the nanoscale surface topography and the specific surface chemistry. This typically manifests in difficulties to control the processing of LIPSS and in limitations to ensure the long-term stability of the created surface functions. Strategies for overcoming such limitations are outlined. T2 - Institutskolloquium des Leibniz-Instituts für Oberflächenmodifizierung CY - Leipzig, Germany DA - 02.02.2023 KW - Laser-induced periodic surface structures (LIPSS) KW - Surface functionalization KW - Industrial applications KW - Femtosecond laser PY - 2023 AN - OPUS4-56949 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Würth, Christian T1 - Time resolved spectroscopy of upconverting lanthanide based upconversion nanocrystals N2 - The optical properties of these materials strongly depend on the excitation power density, i.e., the number of photons absorbed per time interval. The upconversion quantum efficiencies (ΦUC) of these materials, the excitation power dependent population i.e. the emission characteristics, and the deactivation dynamics are influenced by nanoparticle architecture, doping concentration, and the microenvironment. We will discuss how time resolved measurements can help to understand the fundamental photophysical mechanisms and discuss differences to other nanocrystals like quantum dots. T2 - 19th International Course on “Principles and Applications of Time-resolved Fluorescence Spectroscopy” CY - Berlin, Germany DA - 16.11.2022 KW - Nanoparticle KW - Lanthanide KW - Upconversion KW - Energy transfer PY - 2022 AN - OPUS4-57000 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ermilova, Elena A1 - Hertwig, Andreas A1 - Döhring, Thorsten A1 - Stanik, Eva A1 - Cotroneo, Vincenzo A1 - Gibertini, Eugenio T1 - Ellipsometrical characterization of poly-dopamine layers considered for technical applications N2 - Although the organic molecule dopamine (3,4-dihydroxyphenethylamine) is commonly known as the “hormone of happiness”, thin films of poly-dopamine also have interesting technical properties. When produced by dip coating, the self-organizing layers grow in a reproducible thickness of single or multiple molecule monolayers of a few nanometer thickness only. In this work, we introduce a method of determining the layer thickness of poly-dopamine on mirrors for astronomical X-ray telescopes. This work is based on spectroscopic ellipsometry measurements and involves the development of an optical model for the poly-dopamine layers including the dielectric function. Thereby the complex refractive index of the produced layers was determined, covering the range from the ultraviolet to the near infrared spectral region. These measurement results and the corresponding technical challenges are presented in this contribution. Furthermore, an outlook to potential technical applications of this interesting material is given and poly-dopamine layers will make scientist and engineers hopefully happy as an innovative and fascinating technical solution for the future. T2 - SPIE PHOTONICS EUROPE CY - Strasbourg. France DA - 08.04.2024 KW - Polydopamine KW - Thin Solid Layers KW - X-ray optics KW - Spectroscopic Ellipsometry PY - 2024 SN - 978-1-5106-7344-1 DO - https://doi.org/10.1117/12.3015281 VL - 13013 SP - 1 EP - 8 PB - SPIE digital library AN - OPUS4-60954 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Omar, Hassan A1 - Hertwig, Andreas A1 - Szymoniak, Paulina A1 - Schönhals, Andreas T1 - Signature of the Adsorbed Layer on the glass transition of thin polymer Films: Broadband Dielectric spectroscopy and related techniques N2 - In well annealed thin polymer films with non-repulsive polymer/substrate interaction with a substrate an irreversibly adsorbed layer is expected to form. These adsorbed layers have shown a great potential for technological applications [1]. However, the growth kinetics and the molecular mobility of the adsorbed layer is still not fully understood. This concerns also the influence of the adsorbed layer on the thickness dependence of the glass transition temperature of thin films. This is partly due to the difficult accessibility of these layers in thin films. Here, the irreversibly adsorbed layers of semi-rigid mail chain polymers like polycarbonate or polysulfone are revealed by solvent-leaching experiments. First, the growth kinetics of these layers is investigated as a function of annealing time. The film thickness, topography and the quality of the adsorbed layer is controlled by Atomic Force Microscopy (AFM). Secondly, the molecular mobility of the adsorbed layer is investigated by Broadband Dielectric Spectroscopy (BDS). A developed nanostructured capacitor arrangement is employed to measure the layer with a free surface. In addition to the dielectric experiments, spectroscopic Ellipsometry measurements are carried out to estimate the glass transition of the thin films. The thickness dependence of the glass transition of the thin films is correlated with the adsorbed layer [2,3]. Acknowledgments D. Hülagü and G. Hidde thanked for the help with the ellipsometry measurements. T2 - 12. Conference on Broabband Dielectric Spectroscopy and its Application CY - Lisbon, Portugal DA - 01.09.2024 KW - Thin films PY - 2024 AN - OPUS4-60959 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wegner, Karl David A1 - Hildebrandt, N. T1 - Near infrared quantum dots for biosensing and bioimaging N2 - Quantum dots (QDs) possess unique optoelectronic properties, which make them very attractive to be used as optical probes in biosensing and bioimaging applications. The strong absorbance and light scattering of biological compounds like tissue and blood in the visible range pose a problem. However, if optical probes emitting in the near-infrared (NIR) range are used, scattering, absorption, and autofluorescence of biological components are strongly reduced. This allows for an increased light penetration depth and higher spatial and temporal resolution for the investigation of biological processes. The synthesis and application of NIR emitting QDs is a fast-growing research field and the benefits of using QDs were demonstrated for a variety of applications, such as photoelectrochemical biosensor, in vivo vascular imaging, and fluorescence-guided surgery. This article reviews the state-of-the-art developments in the preparation of NIR/IR QDs and highlights the latest research about their utilization in biosensing and bioimaging applications. KW - Quantum dots KW - Near-infrared KW - Biosensing KW - Bioimaging KW - NIR-II / SWIR KW - Advanced nanomaterials PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-609708 SN - 0165-9936 DO - https://doi.org/10.1016/j.trac.2024.117922 VL - 180 SP - 1 EP - 19 PB - Elsevier B.V. AN - OPUS4-60970 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Surface nanotexturing by ultrashort laser pulses N2 - The presentation reviews the BAM activities in the field of surface processing by ultrashort laser pulses. A focus is laid on the generation of laser-induced periodic surface structures (LIPSS) which allow various surface functionalizations for applications in optics, tribology, liquid management, and medicine. T2 - Photonics Days Berlin Brandenburg 2022 CY - Berlin, Germany DA - 05.10.2022 KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser KW - Surface functionalization PY - 2022 AN - OPUS4-55921 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pauw, Brian Richard T1 - The Dark Side of Science (2024.v2 edition) N2 - This talk introduces the dark side of science (the ever increasing levels of fraudulent activities in science and scientific publishing). It furthermore explores why the focus on inherently limited metrics drives this phenomenon, and how one can arm themselves against going down this gradient. Tools and tips are presented to enable assessment of other works, and what can be done in general to move away from this. T2 - Informationsmanagement“ im Master Lebensmitteltechnologie CY - Berlin, Germany DA - 26.11.2024 KW - Research fraud KW - Scientific misconduct KW - Literature research KW - Materials science PY - 2024 AN - OPUS4-61792 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kärcher, Victor A1 - Reiker, Tobias A1 - da Costa, Pedro F.G.M. A1 - de Camargo, Andrea S.S. A1 - Zacharias, Helmut T1 - Quantum control in size selected semiconductor quantum dot thin films N2 - We introduce a novel technique for coherent control that employs resonant internally generated fields in CdTe quantum dot (QD) thin films at the L-point. The bulk band gap of CdTe at the L-point amounts to 3.6 eV, with the transition marked by strong Coulomb coupling. Third harmonic generation (λ3 = 343 nm, hν = 3.61 eV) for a fundamental wavelength of λ 1 = 1,030 nm is used to control quantum interference of three-photon resonant paths between the valence and conduction bands. Different thicknesses of the CdTe QDs are used to manipulate the phase relationship between the external fundamental and the internally generated third harmonic, resulting in either suppression or strong enhancement of the resonant third harmonic, while the nonresonant components remain nearly constant. This development could pave the way for new quantum interference–based applications in ultrafast switching of nanophotonic devices. KW - Nonlinear nanophotonics KW - Quantum interference KW - Third harmonic KW - Coherent control KW - Thin films KW - Quantum dots PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-625859 DO - https://doi.org/10.1515/nanoph-2024-0529 VL - 14 IS - 2 SP - 229 EP - 239 PB - Walter de Gruyter GmbH AN - OPUS4-62585 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Arai, Marylyn Setsuko A1 - Ravaro, Leandro Piaggi A1 - Brambilla, Gabriel A1 - Maia, Lauro June Queiroz A1 - Reza Dousti, Mohammad A1 - de Camargo, Andrea Simone Stucchi T1 - Upconverting Nanoparticles and Cu(I) Complex-Based Platform for Oxygen Sensing, Thermometry, and Emission Color Tuning N2 - Multifunctional nanoplatforms combine different material properties to meet a wide range of applications, allowing highly customizable systems. In this rapidly advancing research field, we introduce a multifunctional nanomaterial based on the synergy between Tm3+-doped upconverting nanoparticles (UCNPs) and a Cu(I) complex (CuCom). This material is designed for oxygen sensing, optical thermometry, and emission color tuning. In various concentrations, the CuCom complex was electrostatically integrated into a mesoporous silica shell surrounding the core UCNPs (UCNP@mSiO2). The optimized system, UCNP@mSiO2@CuCom-10, was evaluated for different applications. Due to the spectral overlap between the CuCom absorption and the nanoparticles emission, excitation at 980 nm allows most of the UV-blue emission output from the UCNPs to be transferred to the CuCom via luminescent resonance energy transfer (LRET), producing red emission from the molecule. The remaining Tm3+ emission enables optical thermometry, while CuCom’s sensitivity to molecular oxygen supports its application in gas sensing. In upconversion mode, the nanoplatform achieved a Stern−Volmer constant for O2 sensing of 1.64 and demonstrated thermometric relative sensitivities of 0.9% and 1% K−1 at room temperature, with a linear response from 193 to 373 K. Additionally, the emission color of UCNP@mSiO2@CuCom-10 can be tuned from blue to white and yellow, by varying the excitation and temperature, adding further functionality to the system. This multifunctional platform suggests promising applications in biology, medicine, and environmental monitoring. KW - M KW - O2 sensing KW - Upconversion KW - Luminescence resonance energy transfer (LRET) KW - Optical thermometry KW - Mesoporous silica shell PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-625869 SN - 2574-0970 DO - https://doi.org/10.1021/acsanm.4c06351 VL - 8 SP - 854 EP - 862 PB - American Chemical Society (ACS) AN - OPUS4-62586 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Omar, Hassan A1 - Ahmadi, Shayan A1 - Szymoniak, Paulina A1 - Schönhals, Andreas T1 - Molecular Mobility of Thin Films of Poly (bisphenol-A carbonate) Capped and with one Free Surface: From Bulk-like Samples down to the Adsorbed Layer N2 - The molecular mobility of thin films of poly(bisphenol A carbonate) (PBAC) was systematically investigated using broadband dielectric spectroscopy, employing two distinct electrode configurations. First, films were prepared in a capped geometry between aluminum electrodes employing a crossed electrode capacitor (CEC) configuration, down to film thicknesses of 40 nm. The Vogel temperature, derived from the temperature dependence of relaxation rate of the α-relaxation, increases with decreasing film thickness characterized by an onset thickness. The onset thickness depends on the annealing conditions, with less intense annealing yielding a lower onset thickness. Additionally, a broadening of the β-relaxation peak was observed with decreasing thickness, attributed to the interaction of phenyl groups with thermally evaporated aluminum, resulting in a shift of certain relaxation modes to higher temperatures relative to the bulk material. A novel phenomenon, termed the slow Arrhenius process (SAP), was also identified in proximity to the α-relaxation temperature. For films with thicknesses below 40 nm, nanostructured electrodes (NSE) were utilized, incorporating nanostructured silica spacers to establish a free surface with air. This free surface causes an enhancement in the molecular mobility for the 40 nm sample, preserving the β-relaxation as a distinct peak. The α-relaxation was detectable in the dielectric loss down to 18 nm, shifting to higher temperatures as film thickness is decreased. Notably, the onset thickness for the increase in Vogel temperature was lower in the NSE configuration compared to the CEC setup, attributed to the presence of the polymer-air interface. KW - Thin polymer films PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623422 DO - https://doi.org/10.1039/d4sm01238k SN - 1744-6848 VL - 21 IS - 2 SP - 241 EP - 254 PB - RSC AN - OPUS4-62342 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - McGonigle, Rebecca A1 - Glasgow, Jodie A1 - Houston, Catriona A1 - Cameron, Iain A1 - Homann, Christian A1 - Black, Dominic J. A1 - Pal, Robert A1 - MacKenzie, Lewis E. ED - MacKenzie, Lewis E. T1 - Autoclave reactor synthesis of upconversion nanoparticles, unreported variables, and safety considerations N2 - Autoclave reactors are widely used across chemical and biological sciences, including for the synthesis of upconversion nanoparticles (UCNPs) and other nanomaterials. Yet, the details of how autoclave reactors are used in such synthesis are rarely reported in the literature, leaving several key synthesis variables widely unreported and thereby hampering experimental reproducibility. In this perspective, we discuss the safety considerations of autoclave reactors and note that autoclaves should only be used if they are (a) purchased from reputable suppliers/manufacturers and (b) have been certified compliant with relevant safety standards. Ultimately, using unsuitable autoclave equipment can pose a severe physical hazard and may breach legal safety requirements. In addition, we highlight several parameters in autoclave synthesis that should be reported as standard to maximise the reproducibility of autoclave synthesis experiments across materials and chemistry research. We encourage users of autoclave synthesis vessels to: (1) adopt high-safety autoclaves and (2) report the many experimental variables involved to enhance experimental reproducibility. KW - Reference material KW - Nano KW - Particle KW - Shell KW - Fluorescence KW - Lifetime KW - Decay kinetics KW - Synthesis KW - Quality assurance KW - Method KW - Energy transfer KW - Upconversion KW - Autoclave synthesis KW - Data comparability PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-625672 DO - https://doi.org/10.1038/s42004-025-01415-3 VL - 8 IS - 1 SP - 1 EP - 7 PB - Springer Science and Business Media LLC AN - OPUS4-62567 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pauw, Brian Richard T1 - AI/ML starts with data, …a practical example N2 - A brief introduction to the efforts we have done in our lab towards AI/ML analysis of SAXS data. For this, we need to extend the data with an extensive, structured hierarchy of metadata and associated data. A practical look into the information stored in our files, and the organization of the files in a data catalog is presented. T2 - Benchmarking for AI for Science at the Exascale A2 Workshop for Materials Science CY - Online meeting DA - 23.11.2020 KW - Small angle scattering KW - Machine learning KW - Data organization KW - Data curation KW - Metadata structuring PY - 2020 AN - OPUS4-51660 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Szymoniak, Paulina T1 - Spatial Inhomogeneity, Interfaces and Complex Vitrification Behavior of Epoxy and Corresponding Nanocomposites by Broadband Dielectric Spectroscopy and Hyphenated Calorimetry N2 - Polymer nanocomposites (PNCs) with inorganic nanofillers dispersed in a polymer matrix have been widely studied from the 1990s, since the pioneering work by Toyota Central Research. The possibility of producing advanced tailor-made, light weight and low-cost materials, inspired academic and commercial research towards numerous potential applications, facilitating PNCs to become a billion-dollar global industry. The introduction of nanoparticles (NPs) to a polymer matrix is expected to result in improved properties. The outstanding performance of PNCs is determined not only by the characteristics of the used components but also by their phase morphology, including the dispersion of NPs and interfacial properties. Understanding of structure-property relationships is particularly important for polymer nanocomposites with high industrial significance, such as epoxy-based materials reinforced with inorganic nanofillers. These PNCs have been successfully adopted by the marine, automotive and aerospace industries, although they are still rarely studied on a fundamental level. Therefore, this thesis aims for a detailed understanding of the structure, molecular mobility and vitrification kinetics first, of two epoxy-based materials with different network structures and second, of the corresponding nanocomposites with different alumina-based nanofillers. The first system considered (EP/T-LDH) was based on bisphenol A diglycidyl ether (DGEBA) cured with diethylenetriamine (DETA) and taurine-modified layered double hydroxide (T-LDH) NPs. The taurine molecule bears additional functionalities that could enhance the interactions between the matrix and the nanofiller, improving the interphase formation. The seconds system (EP/BNP) was based on DGEBA and methyl tetrahydrophtalic acid anhydride (MTHPA) as a hardener, reinforced with boehmite nanoparticles (BNPs). The comparison of the two systems enables for a comparative study on the effect of different hardeners and the morphology and modification of the alumina-based nanofillers on the material behavior. The materials were investigated employing complementary techniques with different sensitivities and frequency windows. The following methodology was used: transmission electron microscopy (TEM), small – and wide – angle X-ray scattering (SAXS/WAXS), broadband dielectric spectroscopy (BDS), calorimetry in a form of conventional DSC and fast scanning calorimetry (FSC), as well as specific heat spectroscopy (SHS) in a form of temperature modulated DSC, temperature modulated FSC and static FSC by calculating the thermal relaxation rates from the cooperativity approach. The FSC method (based on adiabatic chip calorimetry to probe micrometer-sized samples) was successfully employed in this work, exploiting all its possibilities for the first time in literature for a PNC. Moreover, a systematic analysis technique was established to overcome the problem of vague glass transition regions observed for highly loaded PNCs in the heat flow and heat capacity curves. First, TEM, SAXS/WAXS and indirectly BDS and SHS were employed to obtain the information about the approximate morphology of the PNCs. It was found that epoxy-based materials exhibit a structural heterogeneity in a form of regions with different average crosslinking density. This was indicated by multiple-peak scattering pattern of the polymer matrix and two distinct α-processes (dynamic glass transition) related to the cooperative fluctuation of the epoxy network found by BDS and SHS. This was described for the first time for epoxy-based materials. The two α-relaxations were evidenced differently for the two systems, which is related to different network structures and dipole moments due to the employed hardeners. Nevertheless, structural heterogeneity is an intrinsic feature of these materials, independent of the type of hardener used for the network formation and nanofiller. In addition, matrix inhomogeneities were more pronounced with increasing nanoparticle content. Furthermore, a powerful new technique was applied for X-ray scattering data, using Monte Carlo fits, to describe the NPs dispersion throughout the whole sample volume (as opposed to the local investigations performed by most researches). Additional structural information of the two systems was extracted by BDS and SHS, such as qualitative and quantitative estimation of polymer segments physically adsorbed and/or chemically bonded onto the nanoparticles. Due to the immobilized character of this interphase with respect to the cooperative segmental motions, it is denoted as a rigid amorphous fraction (RAF). For instance, on the contrary to EP/BNP, for EP/T-LDH a dielectrically active process was found, related to the localized fluctuations within RAF. Moreover, the amount of RAF in EP/T-LDH was reaching up to 40 wt % of the system, whereas in EP/BNP it ranged between 1-7 wt %. In the latter case the presence of NPs was found to simultaneously increase and decrease the number of mobile segments, due to the interphase formation and changes in crosslinking density. The difference between the two systems was ascribed to the presence of additional amine functionalities in the T-LDH nanofiller. Second, employing BDS and SHS, a systematic study on the effect of NPs on the segmental dynamics was performed. For example, depending on the nanofiller, the α-processes related to regions with higher crosslinking density was found to shift to higher and lower temperatures with increasing T-LDH and BNPs concentration, respectively. The observed difference is due to the different synergism of the polymer matrix with the nanofiller. Third, a detailed investigation of the vitrification kinetics was performed with DSC and FSC. The concentration dependence of the glass transition temperature was found, similar to the behavior of the α-processes. It was shown that, in parallel to the detected main glass transition, epoxy-based materials can exhibit an additional low temperature vitrification mechanism. As expected from the two distinct α-processes, this behavior was however not discussed in prior studies for an unfilled network former. This finding was correlated to the structural heterogeneity evidenced by other techniques. This thesis, dealing with an in-depth research on the epoxy-based materials that are already successfully employed in numerous applications underlines the necessity of more fundamental research in this field. It shines light on the complexity of these systems and contributes to defining how the structure-property relationships can be determined by combining multiple experimental techniques and analytical methodology. T2 - PhD defense CY - Online meeting DA - 18.12.2020 KW - Interfaces KW - Nanocomposites KW - Rigid amorphous fraction KW - TMDSC KW - BDS PY - 2020 AN - OPUS4-52035 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Tache, O. T1 - Synthesis of SiO2 Nanoparticles as reference materials: Metrological measurements and in-situ kinetics in lab with Small Angle X-Ray Scattering N2 - The unambiguous correlation of possible health and sustainability risks to nanoparticle size must be enabled by reliable measurement of nanoparticle size, to ensure comparability and compatibility between results measured under different methods. The NPSIZE project funded by European Metrology Program (EMPIR) develop methods, reference materials and modelling to improve the traceability chain, comparability and compatibility of nanoparticle size measurements. In this work, we present how spherical silica nanoparticles are synthetized with controlled monomodal or bimodal dispersion to be use as reference materials and international round-robin. Improving the fabrication requires a fine understanding of synthesis (1), coupled with an expertise of in-situ or ex-situ analysis methods. This is a new challenge for the analysis : determining not only average characteristics (size, chemical composition and shape ...) but also the concentration and the distribution over the population studied (2). Small-Angle X-ray Scattering (3) allows very precise measurements of the nanoparticles size and concentration that can be directly link to the metric system (4) (metrological traceability) . We developed a SAXS laboratory instrument dedicated to the in-situ characterization of nanoparticles, which enable fast measurements, and the monitoring of the synthesis parameters. Measurement protocols and software processing chain (5) (i.e. size distribution) are also combined & optimized. T2 - CNANO2021 CY - Toulouse, France DA - 25.11.2021 KW - X-ray scattering KW - Silica particles KW - Synthesis KW - Reference materials PY - 2021 DO - https://doi.org/10.5281/zenodo.5749256 AN - OPUS4-53931 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kuchenbecker, Petra T1 - Praktische Erfahrungen zur Granulometrie von Pulvern im Submikron- und Nanobereich N2 - Der Vortrag beleuchtet insbesondere die Herausforderungen die sich bei der Dispergierung der Nanopulver aufgrund der hohen Adhäsivkräfte ergeben. Die Bewertung der Probenpräparation ist nur indirekt zugänglich, aber essentiell für die Zuverlässigkeit der Messergebnisse. Anhand von Beispielen werden Lösungsvorschläge aufgezeigt. Der Vortrag schließt mit einem Vorschlag zur Strategie der Herangehensweise bei der Partikelgrößenbestimmung von Nanopulvern. T2 - Sitzung des Fachausschusses "Material- und Prozessdiagnostik" der Deutschen Keramischen Gesellschaft: Zuverlässige granulometrische Charakterisierung von Mikro- und Nanopulvern – Voraussetzung für optimierte Keramikwerkstoffe in der Energietechnik CY - Online meeting DA - 19.11.2020 KW - Nano-powder KW - particle size determination KW - dispersion KW - sample preparation PY - 2020 AN - OPUS4-51665 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Szymoniak, Paulina T1 - Spatial Inhomogeneity, Interfaces and Complex Vitrification Behavior of Epoxy-based Materials by Broadband Dielectric Spectroscopy and Calorimetry N2 - Although in the last decades epoxy-based nanocomposites have been successfully adopted by the marine, automotive and aerospace industries they are still rarely studied on a fundamental level. This work deals with an in-depth comparative investigation of the structure, molecular mobility and vitrification kinetics of three bisphenol A diglycidyl ether (DGEBA)-based materials with different nanofillers: I) taurine-modified layered double hydroxide (T-LDH), II) boehmite (BNPs) and III) halloysite nanotubes (HNTs). Moreover, the effect of different hardeners (diethylene triamine and methyl tetrahydrophtalic acid anhydride) on the unfilled epoxy matrix is addressed as well. The chosen methodology comprises I) small – and wide – angle X-ray scattering (SAXS/WAXS) II) calorimetry in the forms of a) conventional DSC and b) static fast scanning calorimetry (FSC), III) broadband dielectric spectroscopy (BDS), as well as IV) specific heat spectroscopy in the forms of a) temperature modulated DSC, and b) temperature modulated FSC. The combination of these techniques proved an intrinsic spatial heterogeneity of epoxy-based materials, evidenced by two separate segmental relaxation processes. Although, depending on the hardener the response of the systems to calorimetric and dielectric investigations was different, in a broader sense similar conclusions can be extracted on the structural heterogeneity. As expected from the two distinct α-processes, it was shown that, in parallel to the main glass transition, epoxy-based materials can exhibit an additional low temperature vitrification mechanism, which was not discussed in prior studies for an unfilled network former. Furthermore, the interfacial region (so-called rigid amorphous fraction) was qualitatively and quantitatively addressed, in dependence of the employed nanofiller structure. T2 - Webinar University of Southern Denmark CY - Online meeting DA - 20.01.2021 KW - BDS KW - Nanocomposites KW - Epoxy KW - Rigid amorphous fraction KW - TMDSC KW - Flash DSC PY - 2021 AN - OPUS4-52036 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Laser-induced periodic surface structures: When electromagnetics drives hydrodynamics N2 - Laser-induced Periodic Surface Structures (LIPSS, ripples) are a universal phenomenon and can be generated in a contactless, single-step process on almost any material upon irradiation of solids with intense laser radiation. Nowadays processing rates of up to m^2/min are enabling new industrial applications in medicine, optics, tribology, biology, etc. Depending on the specific type of LIPSS, their structural sizes typically range from several micrometers down to less than 100 nanometers – far beyond the optical diffraction limit – while their orientations exhibit a clear correlation with the local polarization direction of the laser radiation. From a theoretical point of view, however, a vivid, controversial, and long-lasting debate has emerged during the last two decades, whether LIPSS originate from electromagnetic effects (seeded already during the laser irradiation) – or whether they emerge from matter reorganization processes (distinctly after the laser irradiation). This presentation reviews the currently existent theories of LIPSS. A focus is laid on the historic development of the fundamental ideas, their corresponding mathematical descriptions and numerical implementations, along with a comparison and critical assessment of the different approaches. T2 - 28th International Conference on Advanced Laser Technologies (ALT'21) CY - Online meeting DA - 06.09.2021 KW - Laser-induced periodic surface structures, LIPSS KW - Electromagnetic scattering KW - Matter reorganization PY - 2021 DO - https://doi.org/10.24412/cl-35039-2021-21-25-25 AN - OPUS4-53218 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kolmangadi, Mohamed Aejaz T1 - Phase Behaviour and Molecular Mobility of a confined Ionic Liquid Crystal N2 - Liquid crystalline mesophases in nanoconfinement exhibit intriguing orientational order and phase transition behaviors. Here, the plastic crystal to hexagonal columnar, and hexagonal columnar to isotropic transition temperatures are studied for the guanidinium-based ionic discotic liquid crystal confined in self- ordered nanoporous alumina membranes. The phase transition temperature of the plastic crystal to hexagonal columnar phase is reduced with inverse pore diameter. The hexagonal columnar to isotropic transition is suppressed completely in all pores and a possible explanation is given. The results are of technological relevance for the design of liquid crystal-based devices such as batteries and sensors with optimum tunable properties. T2 - Interpore Konferenz CY - Online meeting DA - 31.05.2021 KW - Ionic Liquid crystals KW - Nanoconfinement KW - Conductivity PY - 2021 AN - OPUS4-53298 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stawski, Tomasz T1 - Scattering is a powerful tool to follow nucleation and growth of minerals from solutions N2 - In recent years, we have come to appreciate the astounding intricacy of the formation process of minerals from ions in aqueous solutions. The original ‘textbook’ image of these phenomena, stemming from the adaptation of classical nucleation and growth theories, has increased in complexity due to the discovery of a variety of precursor and intermediate species [e.g. 1], including solute clusters (e.g. prenucleation clusters, PNCs), liquid(-like) phases, as well as amorphous and nanocrystalline solids etc. In general, these precursor or intermediate species constitute different, often short-lived, points along the pathway from dissolved ions to the final solids (typically crystals in this context). In this regard synchrotron-based scattering (SAXS/WAXS/HEXD) appears to be the perfect tool to follow in situ and in a time-resolved manner the crystallization pathways because of the temporal and spatial length scales that can be directly accessed with these techniques. Here, we show how we used scattering to probe the crystallization mechanisms of calcium sulfate. CaSO4 minerals (i.e. gypsum, anhydrite and bassanite) are widespread in natural and industrial environments. During the last several years, a number of studies have revealed indeed that nucleation in the CaSO4-H2O system is non-classical. Our SAXS data demonstrate that gypsum precipitation, involves formation and aggregation of sub-3 nm primary species. These species constitute building blocks of an amorphous precursor phase [2]. Further, we show how in situ high-energy X-ray diffraction experiments and molecular dynamics (MD) simulations can be combined to derive the atomic structure of the primary CaSO4 clusters seen at small-angles [3]. We fitted several plausible structures to the derived pair distribution functions and explored their dynamic properties using unbiased MD simulations based on polarizable force fields. Finally, based on combined SAXS/WAXS, broad-q-range measurements, we show that the process of formation of bassanite, a less hydrated form of CaSO4, is very similar to the formation of gypsum: it also involves the aggregation of small primary species into larger disordered aggregates [4]. Based on these recent insights we formulated a tentative general model for calcium sulfate precipitation from solution. This model involves primary species that are formed through the assembly of multiple Ca2+ and SO42- ions into nanoclusters. These nanoclusters assemble into poorly ordered (i.e. amorphous) hydrated aggregates, which in turn undergo ordering into coherent crystalline units of either gypsum or bassanite (and possibly anhydrite). Determination of the structure and (meta)stability of the primary species is important from both a fundamental, e.g. establishing a general non-classical nucleation model, and applied perspective; e.g. allow for an improved design of additives for greater control of the nucleation pathway. T2 - Annual Meeting of German Crystallographic Society (29. Jahrestagung der Deutschen Gesellschaft für Kristallographie - DGK CY - Online meeting DA - 15.03.2021 KW - Scattering KW - Calcium sulfate KW - SAXS/WAXS PY - 2021 AN - OPUS4-53619 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kolmangadi, Mohamed Aejaz T1 - ILC Meeting N2 - We summarized our recent findings about the molecular dynamics investigation of bulk and finite ionic liquid crystals. We investigate the molecular dynamics and electrical conductivity for a homologous series of linear shaped guanidinium based cyclic ILCs that vary in alkyl chain length, CLCRs (R = 8, 10, 12, 14, 16) by employing broadband dielectric spectroscopy (BDS), and calorimetry comprised of Fast Scanning Calorimetry (FSC) and temperature modulated FSC (TMFSC). Besides conductivity at high temperatures, the dielectric dispersion reveals two relaxation modes: the fast γ and the slow α1 relaxation. The former is assigned to the localized fluctuations while the latter is due to segmental dynamics of the alkyl chains. The γ mode slows down for long chain length CLCs (12,14,16) compared to their shorter analogues. Calorimetric investigation reveals one process, the α2 process, for CLC12,14 and 16 and two processes, α2 and α3, for CLC8 and 10. The α2 process of all CLCRs has a similar temperature dependence as the dielectric α1 relaxation, which indicates both BDS and FSC probe the segmental dynamics of alkyl side chains, as observed for the bent shaped cyclic ILCs. We interpret the α3 process of CLC8 and 10 as the segmental dynamics of the cation core. For all CLCRs, the absolute values of DC conductivity increase by 4 orders of magnitude at the transition from the plastic crystalline to hexagonal columnar phase. This increase is due to the change in the underlying conduction mechanism from delocalized electron hopping in the crystalline phase to one dimensional ion mobility in the columnar phase. The glassy dynamics shifts to higher temperatures with increasing alkyl chain length. Conversely, the DC conductivity drops by 3 orders of magnitude from CLC8 to CLC16. T2 - ILC Project Meeting CY - Berlin, Germany DA - 14.09.2021 KW - Ionic Liquid crystals KW - Nanoconfinement KW - Conductivity PY - 2021 AN - OPUS4-53675 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bresch, Harald T1 - Nanomaterial characterisation - The long way to standardisation N2 - In 1981 the OECD published the Test Guideline on Particle size and size distribution. This TG is still a valid document for the measurement of particles all over the world. When nanomaterials gained importance, ISO set up a technical commitee for Nanotechnologies in 2005 and the OECD followed this step in 2006 with the Working Party on Manufactured Nanomaterials. In the following years ISO and OECD published several documents about nanomaterials and the systematisation developed. In 2017 it was finally clear that nanomaterials need to be adressed in another way than chemicals and in 2020 ECHA revised the REACH-Annexes accordingly and included nanomaterials. Unfortunately there is a little problem with this: Only a few applicable test guidelines exit for the measurement of the nanomaterials. Several test guidelines date from 1981 and do not address nanomaterials. The logical next step for the OECD would be to publish a series of test guidelines which are indeed currently prepared and will be shown in this talk. Finally there is an additional need for the future of NM standardisation: Digitalisation. T2 - Bilateral workshop with Uni Bermingham CY - Online meeting DA - 10.03.2021 KW - Nano KW - Standardisation KW - Test guideline KW - OECD KW - Nanomaterial PY - 2021 AN - OPUS4-53822 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bresch, Harald T1 - Size matters! - Auf dem Weg zu einer neuen OECD Prüfrichtlinie zur Bestimmung der Partikelgröße und Anzahlgrößenverteilung von Nanomaterialien N2 - Vorstellung der Ergebnisse bei der Entwicklung einer neuen OECD Prüfrichtlinie zur Bestimmung der Partikelgröße und Anzahlgrößenverteilung von Nanomaterialien. Ergebnisse: Ideal sphärische Partikel sind gut und verlässlich mit vielen Methoden charakterisierbar. Reale (Nicht ideale) Materialien sind gut charakterisierbar, wenn eine gewisse Homogenität und Stabilität vorliegt. Stark inhomogene und stark agglomerierende Partikel liefern deutlich unterschiedliche Ergebnisse für verschiedene Methoden. Partikel mit geringen Größenunterschieden lassen sich mit allen Methoden gut charakterisieren. Partikel mit sehr deutlichen Größenunterschieden führen häufig zu einer Unterbewertung der kleineren Partikel. Vollautomatische Partikeldetektion bei elektronenmikroskopischen Aufnahmen ist z.Zt. noch stark fehleranfällig und kann daher nicht empfohlen werden. Es hat sich gezeigt, dass alle Methoden zur Bestimmung der Partikelgrößenverteilung Vor- und Nachteile haben. Es ist dringend zu empfehlen Größenverteilungen immer mit mindestens zwei unterschiedlichen Methoden zu bestimmen: Bildgebend und mit gute Anzahlstatistik. Verschiedene Durchmesser wurden in der TG-PSD mit einem Indexsystem versehen, welches zukünftig Verwechslungen zwischen unterschiedlichen Durchmessern vermeiden soll. Wird ein bestimmter Durchmesser benötigt (z.B. hydrodynamisch, aerodynamisch), muss die Methode passend gewählt werden. Eine Umrechnung von einem Durchmesser in einen anderen ist in der Regel fehlerbehaftet. Es wurde ein einheitliches Reporting-System in der TG-PSD eingeführt. T2 - Fachseminar des Umweltbundesamtes CY - Online meeting DA - 14.04.2021 KW - Nano KW - OECD KW - Prüfrichtlinie KW - Nanomaterial KW - BMU PY - 2021 AN - OPUS4-53823 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bresch, Harald T1 - OECD Prüfrichtlinie zur Bestimmung der Partikelgröße und Anzahlgrößenverteilung von Nanomaterialien N2 - Abschlusspräsentation des Projektes "OECD Prüfrichtlinie zur Bestimmung der Partikelgröße und Anzahlgrößenverteilung von Nanomaterialien" - Projektteil Nanopartikel. Es hat sich gezeigt, dass alle Methoden zur Bestimmung der Partikelgrößenverteilung Vor- und Nachteile haben. Es wird dringend empfohlen Größenverteilungen immer mit mindestens zwei unterschiedlichen Methoden zu bestimmen: Bildgebend und mit gute Anzahlstatistik. Verschiedene Durchmesser wurden in der TG-PSD mit einem Indexsystem versehen, welches zukünftig Verwechslungen zwischen unterschiedlichen Durchmessern vermeiden soll. Wird ein bestimmter Durchmesser benötigt (z.B. hydrodynamisch, aerodynamisch), muss die Methode passend gewählt werden. Eine Umrechnung von einem Durchmesser in einen anderen ist in der Regel fehlerbehaftet. Es wurde ein einheitliches Reporting-System in der TG-PSD eingeführt. T2 - Fachgespräch zur OECD - TG PSD - BMU BMWi BAM BAuA UBA CY - Online meeting DA - 10.09.2021 KW - Nano KW - OECD KW - Nanopartikel KW - Prürfrichtlinie KW - Nanomaterial PY - 2021 AN - OPUS4-53825 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Florian, Camilo T1 - Femtosecond laser-induced oxidation in the formation of periodic surface structures N2 - Laser-induced oxide graded layers may contribute to the formation of a new type of embedded low-spatial frequency LIPSS with an anomalous orientation parallel to the laser polarization. In this contribution, we explore this effect experimentally with femtosecond laser pulses and numerically by finite-difference time-domain (FDTD) calculations. T2 - 2021 Conference on Lasers and Electro-Optics/Europe – European Quantum Electronics Virtual Conferences CY - Online meeting DA - 21.06.2021 KW - Laser-induced periodic surface structures (LIPSS) KW - Surface oxidation KW - Femtosecond laser ablation KW - Finite-difference time-domain calculations PY - 2021 AN - OPUS4-52859 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kuchenbecker, Petra T1 - Sample Preparation of Nano-Powders for Particle Size Determination N2 - The use of increasingly finer starting powders up to nanopowders can also be observed in the field of ceramics. Their advantages consist, for example, in their lower activation energy, an increase in strength or unique optical properties. However, handling and characterization of the powders are much more difficult. The main reason for this is the very high adhesive forces between the particles and between particles and other surfaces, too. Therefore, submicron and even more so nanoparticles tend to agglomerate and their separation into primary particles during sample preparation prior to particle sizing is of particular challenge. A representative measurement sample is only obtained when it no longer contains agglomerates. The evaluation of the dispersion process and a decision on whether it was successful thus increases in importance for the reliability of the measurement results of particle sizing. The presentation uses examples to show possible approaches and provides information on possible sources of error. It is shown that successful granulometric characterisation of fine powders requires both an improved dispersion technique and very often an effective combination of two or more measurement methods. T2 - 96. Jahrestagung der Deutschen Keramischen Gesellschaft CY - Online Meeting DA - 19.04.2021 KW - Agglomerates KW - Nano-powder KW - Dispersion process PY - 2021 AN - OPUS4-52503 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fiedler, Saskia T1 - Giant photon bunching of WS2 monolayer in cathodoluminescence N2 - Cathodoluminescence (CL) spectroscopy has become a powerful tool to study nanostructures due to its high spectral and spatial resolution down to sub-nanometer. More recently, CL technique has also been used for second order auto-correlation measurements (g(2)(t)) to identify different single photon emitters and photon bunching in different materials [1-2]. In this work, tungsten disulfide (WS2) monolayers encapsulated in hexagonal boron nitride (hBN) with and without monocrystalline Au nanodisks (NDs) have been studied, using CL and PL spectroscopy as well as g(2)-CL- and PL-measurements. CL and PL maps of different WS2 monolayers before/after Au ND deposition show a narrow peak at ~625 nm without any background emission. In CL, the hBN not only protects WS2 from the electron beam but also acts as a charge carrier sink which substantially increases the CL signal [3]. A further CL enhancement is achieved by Au ND deposition, exhibiting the maximum at the center of the NDs without any size dependence. The PL intensity is unaffected. This indicates that Purcell enhancement cannot be the underlying mechanism. Furthermore, a giant CL-photon bunching of the hBN-encapsulated WS2 monolayers is found which is independent of the applied voltage but highly dependent on the electron beam current. At the lowest current of ~2 pA, a CL bunching factor of up to 160 is observed. Varying thicknesses of the surrounding hBN increases the overall CL signal but does not affect the bunching factor, though it exhibits small local changes within the same flake. In contrast, there is no PL correlation (g(2)(0) = 1). Interestingly, this photon bunching can be further increased by Au NDs, resulting in the highest ever observed bunching factor of close to 2200. Once again, this enhancement is independent of the Au ND’s diameter although some disks show higher bunching factors than others. Most likely, the Au acts as shield for the incoming primary electrons, resulting in an even further decreased current, and thereby, increased bunching. In conclusion, large CL-photon bunching is found in hBN-encapsulated WS2 monolayers which can be substantially enhanced by Au NDs. References [1] M.A. Feldmann, E.F. Demitrescu, D. Bridges, M.F. Chisholm, R.B. Davidson, P.G. Evans, J.A. Hachtel, A. Hu, R.C. Pooser, R.F. Haglund, B.J. Lawrie, Phys. Rev. B, 97, 081404(R) (2018) [2] S. Meuret, L.H.G. Tizei, T. Cazimajou, R. Bourrellier, H.C. Chang, F. Treussartm M. Kociak, Phys. Rev. Letter, 114, 197401 (2015) [3] S. Zheng, J.-K. So, F. Liu, Z. Liu, N. Zheludev, H.J. Fan, Nano Lett., 17, 6475-6480 (2017) T2 - GSELOP2021 CY - Paris, France DA - 23.08.2021 KW - Cathodoluminescence KW - Photon bunching KW - 2D materials KW - TMDCs KW - Au nanodisks KW - Transition metal dichalcogenide KW - Au nanoparticles PY - 2021 AN - OPUS4-53153 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Florian, Camilo T1 - Silicon surface amorphization and re-crystallization via single femtosecond laser pulses N2 - Silicon is the material responsible for most of the technological developments during the past century, making it one of the most studied materials along different disciplines. However, there are still unturned stones regarding its superficial re-solidification after femtosecond laser-induced local melting. In this presentation, we report irradiation experiments with single femtosecond pulses (790 nm, 30 fs) with a spatially Gaussian distribution on two different types of silicon with orientations <111> and <100>. The surface modifications were studied in detail via different techniques, including optical microscopy, atomic force microscopy, spectroscopic imaging ellipsometry, energy dispersive X-ray spectroscopy and high-resolution transmission electron microscopy. We quantitatively estimate the resulting radial amorphous layer depth profiles with maximum thicknesses around some tenths of nanometers for fluences in between the melting and ablation thresholds. In particular, spectroscopic imaging ellipsometry (SIE) allowed fast data acquisition using multiple wavelengths to provide experimental measurements for calculating the nanometric radial amorphous layer thickness profiles with micrometric lateral resolution based on a thin-film layer model. SIE proved to be capable of detecting and measuring nanometric structural and chemical modifications (oxidation) on the studied laser spots. The accuracy of the SIE-based calculations is verified experimentally by characterizing an in-depth material lamella via high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (STEM-EDX). For completeness, we present a mathematical modelling for the melt layer thickness considering different optical absorption processes including one photon absorption, two photon absorption and free-carrier absorption, highlighting the relevance of the latter one in the femtosecond laser-induced melting of silicon. T2 - 28th International Conference on Advanced Laser Technologies (ALT'21) CY - Online meeting DA - 06.09.2021 KW - Silicon KW - Femtosecond laser KW - Phase transitions KW - Spectroscopic imaging ellipsometry KW - Transmission electron microscopy PY - 2021 AN - OPUS4-53235 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Omar, Hassan A1 - Hiid, Gundula A1 - Szymoniak, Paulina A1 - Hertwig, Andreas A1 - Schönhals, Andreas T1 - Growth kinetics of the adsorbed layer of poly(bisphenol A carbonate) and its effect on the glass transition behavior in thin films N2 - The glass transition behavior of thin films of poly(bisphenol A carbonate) (PBAC) was studied employing ellipsometry. The glass transition temperature increases with the reduction of the film thickness. This result is attributed to the formation of an adsorbed layer with a reduced mobility compared to bulk PBAC. Therefore, for the first time, the growth kinetics of the adsorbed layer of PBAC was investigated, prepared by leaching samples from a 200 nm thin film which were annealed for several times at three different temperatures. The thickness of each prepared adsorbed layer was measured by multiple scans using atomic force microscopy (AFM). Additionally, an unannealed sample was measured. Comparison of the measurements of the unannealed and the annealed samples provides proof of a pre-growth regime for all annealing temperatures which was not observed for other polymers. For the lowest annealing temperature after the pre-growth stage only a growth regime with a linear time dependence is observed. For higher annealing temperatures the growth kinetics changes from a linear to a logarithmic growth regime at a critical time. At the longest annealing times the films showed signs of dewetting where segments of the adsorbed film were removed from the substrate (dewetting by desorption). The dependence of the surface roughness of the PBAC surface on annealing time also confirmed that the films annealed at highest temperatures for the longest times desorbed from the substrate. KW - Ultra thin polymer films PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-574531 DO - https://doi.org/10.1039/D3RA02020G SN - 2046-2069 VL - 13 IS - 21 SP - 14473 EP - 14483 PB - RSC Publishing CY - London AN - OPUS4-57453 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fritzsche, Sven A1 - Pauw, Brian Richard A1 - Weimann, Christiane A1 - Sturm, Heinz T1 - First of its kind: A test artifact for direct laser writing N2 - With femtosecond-laser direct writing (fs-LDW) maturing in all aspects as a manufacturing technology, a toolset for quality assurance must be developed. In this work we introduce a first of its kind test artifact. Test artifacts are standardized 3D models with specific geometric features to evaluate the performance of writing parameters. Test artifacts are already common in other 3D additive manufacturing technologies e.g. selective laser melting. The test artifact introduced in this work was developed in particular to accommodate the high geometrical resolution of fs-LDW structures and the limited possibilities to examine the resulting structure. Geometric accuracy, surface adhesion as well as confocal Raman spectroscopy results were considered when evaluating the design of the test artifact. We will explain the individual features and design considerations of our fs-LDW test artifact. The difference between two slicers, Cura and 3DPoli, and the implications on measured feature sizes and the general shape is quantified. The measured geometries are used to derive a general design guide for a specific combination of photoresists, laser power and scanning speed and to analyze the geometric accuracy of a structure produced using these guidelines. The shown test artifact is publicly available as STL file on GitHub (https://github.com/BAMresearch/2PP-TestArtifact) and in the supplement. KW - Laser direct writing KW - Multi photon lithography KW - Reference material KW - Raman spectroscopy KW - Confocal raman imaging KW - Slicers KW - Open data on zenodo PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-580951 DO - https://doi.org/10.1088/1361-6501/acc47a VL - 34 IS - 7 SP - 1 EP - 14 PB - IOP Science AN - OPUS4-58095 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fiedler, Saskia A1 - Ton-That, C. A1 - Phillips, M. R. T1 - Defect-free ZnO nanorods with high angular distribution for enhanced excitonic emission N2 - AbstractLow-temperature hydrothermal growth has emerged as a popular method for the fabrication of ZnO nanorods (NRs), increasing the functionality and utility of ZnO-based devices. In this work, we study the influence of growth time, temperature and seed layer on the dimensions and angular distribution of ZnO NRs. High-quality NRs with a crisscrossed 60° angular distribution have been grown with a 20–60 nm diameter and 600 nm length. We show that, within the ideal range of growth parameters, the growth time and temperature have no controllable influence on NR diameter and length, while the deposition method and size of the pre-growth deposited ZnO seeds affects diameter and NR angular alignment. We demonstrate advantages of using crisscross-aligned NRs over planar ZnO for the enhancement of ZnO excitonic emission by optical coupling with gold nanoparticles. These results can be readily adapted for applications that involve surface coating-mediated enhancement of both light emission and injection. KW - ZnO nanorod KW - Hydrothermal growth KW - Seed layer KW - Angular distribution KW - Cathodoluminescence KW - Luminescence enhancement PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-618176 DO - https://doi.org/10.1557/s43578-023-00941-x SN - 0884-2914 SN - 2044-5326 VL - 38 IS - 8 SP - 2145 EP - 2155 PB - Springer CY - Berlin AN - OPUS4-61817 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schardt, Annika A1 - Schmitt, Johannes A1 - Engelhard, Carsten T1 - Single particle inductively coupled plasma mass spectrometry with nanosecond time resolution N2 - In this proof-of-principle study, we present our contribution to single particle inductively coupled plasma mass spectrometry (spICP-MS) developments with a novel in-house built data acquisition system with nanosecond time resolution (nanoDAQ) and a matching data processing approach. The new system can continuously sample the secondary electron multiplier (SEM) detector signal and enables the detection of gold nanoparticles (AuNP) as small as 7.5 nm with the commercial single quadrupole ICP-MS instrument used in this study. Recording of the SEM signal by the nanoDAQ is performed with a dwell time of approximately 4 ns. A tailored method was developed to process this type of transient data, which is based on determining the temporal distance between detector events that is denoted as event gap (EG). We found that the inverse logarithm of EG is proportional to the particle size and that the number of detector events corresponding to a particle signal distribution can be used to calibrate and determine the particle number concentration (PNC) of a nanoparticle dispersion. Due to the high data acquisition frequency, a statistically significant number of data points can be obtained in 60 s or less and the main time limitation for analyses is merely the sample uptake time and rinsing step between analyte solutions. At this stage, the data processing method provides average information on complete data sets only and will be adapted to enable particle-by-particle analysis with future hardware/software revision. KW - ICP-MS KW - Nanoparticles KW - Nanosecond time resolution KW - Single particle detection PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612706 DO - https://doi.org/10.1039/d3ja00373f SN - 1364-5544 SN - 0267-9477 VL - 39 IS - 2 SP - 389 EP - 400 PB - Royal Society of Chemistry (RSC) CY - Cambridge AN - OPUS4-61270 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mezera, Marek A1 - Alamri, S. A1 - Hendriks, W. A. P. M. A1 - Hertwig, Andreas A1 - Elert, Anna Maria A1 - Bonse, Jörn A1 - Kunze, T. A1 - Lasagni, A. F. A1 - Römer, G. R. B. E. T1 - Hierarchical micro-/nano-structures on polycarbonate via UV pulsed laser processing N2 - Hierarchical micro/-nanostructures were produced on polycarbonate polymer surfaces by employing a two-step UV-laser processing strategy based on the combination of Direct Laser Interference Patterning (DLIP) of gratings and pillars on the microscale (3 ns, 266 nm, 2 kHz) and subsequently superimposing Laser-induced Periodic Surface Structures (LIPSS; 7–10 ps, 350 nm, 100 kHz) which adds nanoscale surface features. Particular emphasis was laid on the influence of the direction of the laser beam polarization on the morphology of resulting hierarchical surfaces. Scanning electron and atomic force microscopy methods were used for the characterization of the hybrid surface structures. Finite-difference time-domain (FDTD) calculations of the laser intensity distribution on the DLIP structures allowed to address the specific polarization dependence of the LIPSS formation observed in the second processing step. Complementary chemical analyzes by micro-Raman spectroscopy and attenuated total reflection Fourier-transform infrared spectroscopy provided in-depth information on the chemical and structural material modifications and material degradation imposed by the laser processing. It was found that when the linear laser polarization was set perpendicular to the DLIP ridges, LIPSS could be formed on top of various DLIP structures. FDTD calculations showed enhanced optical intensity at the topographic maxima, which can explain the dependency of the morphology of LIPSS on the polarization with respect to the orientation of the DLIP structures. It was also found that the degradation of the polymer was enhanced for increasing accumulated fluence levels. KW - Direct laser interference patterning KW - Laser-induced periodic surface structures (LIPSS) KW - Polycarbonate KW - Hierarchical structures KW - Surface functionalization PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509101 DO - https://doi.org/10.3390/nano10061184 SN - 2079-4991 VL - 10(6) IS - Special issue "Laser-generated periodic nanostructures" SP - 1184-1 EP - 1184-19 PB - MDPI CY - Basel AN - OPUS4-50910 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fosodeder, P. A1 - Baumgartner, W. A1 - Steinwender, C. A1 - Hassel, A. W. A1 - Florian, Camilo A1 - Bonse, Jörn A1 - Heitz, J. T1 - Repellent rings at titanium cylinders against overgrowth by fibroblasts N2 - The invention of new miniaturized and smart medical implants continues in all medical fields, including miniaturized heart pacemakers. These implants often come with a titanium (Ti) casing, which may have to be removed after several months or years and shall therefore not be completely overgrown by cells or scar tissue after implantation. Scar tissue is mainly formed by fibroblast cells and extracellular matrix proteins like collagen produced by them. Suppression of fibroblast growth at Ti surfaces could be achieved by 800 nm femtosecond laser-ablation creating self-organized sharp spikes with dimensions in the 10 μm-range which are superposed by fine sub-μm parallel ripples. On flat Ti control samples, the best results regarding suppression of cell growth were obtained on spike-structures which were additionally electrochemically anodized under acidic conditions. When Ti cylinders with a diameter of 8 mm (similar as the pacemakers) were placed upright in a culture of murine fibroblasts, a multi-layer cell growth up to a height of at least 1.5 mm occurred within 19–22 days. We have demonstrated that a laser-structured and anodized ring around the Ti cylinder surface is an effective way to create a barrier that murine fibroblasts were not able to overgrow within this time. KW - Cell-repellent surfaces KW - Femtosecond laser-processing KW - Electrochemical treatment KW - Laser-induced micro- and nanostructures KW - Medical implants PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509966 DO - https://doi.org/10.1515/aot-2019-0070 SN - 2193-8576 SN - 2193-8584 VL - 9 IS - 3 (Topical issue: Laser micro- and nano-material processing - Part 2) SP - 113 EP - 120 PB - De Gruyter CY - Berlin AN - OPUS4-50996 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -