TY - CONF A1 - Chemello, Giovanni A1 - Hodoroaba, Vasile-Dan A1 - Radnik, Jörg T1 - Characterization of Graphene using HAXPES N2 - Since its discovery, graphene has got growing attention in the industrial and application research due to its unique properties . However, graphene has not been yet implemented into the industrial market, in particularly due to the difficulty of properly characterizing this challenging material. As most of other nanomaterials, graphene’s properties are closely linked to its chemical and structural properties, such as number of layers, flake thickness, degree of functionalisation and C/O ratio. For the commercialization, suitable procedures for the measurement and characterization of the ultrathin flakes, of lateral dimensions in the range from µm to tens of µm, are essential.Surface chemical methods, especially XPS, have an outstanding role of providing chemical information on the composition. Thereby, one well-known problem for surface analytical methods is the influence of contamination on the composition as in the case of adventitious carbon. The differentiation between carbon originated from the contamination or from the graphene sample itself is often not obvious, which can lead to altered results in the determination of the composition. To overcome this problem, Hard Energy X-ray Photoelectron Spectroscopy (HAXPES) offers new possibilities due to its higher information depth. Therefore, XPS measurement obtained with Al Kα radiation (E = 1486. 6 eV) were compared with analyses performed with a Cr Kα (E = 5414. 8 eV) excitation on functionalized graphene samples. Differences are discussed in terms of potential carbon contamination, but also of oxygen on the composition of the samples. Measurements are performed on O-, N- and F-functionalized graphene. Different preparation procedures (powder, pellet, drop cast from liquid suspension) will be also discussed, correlation of the results with the flakes morphology as well as their validation with other independent methods are in progress. T2 - ECASIA 2022 CY - Limerick, Ireland DA - 29.05.2022 KW - Graphene KW - Functionalized graphene KW - Depth profiling PY - 2022 AN - OPUS4-56814 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute A1 - Keller, Lisa-Marie A1 - Scholz, Lena A1 - Weigert, Florian A1 - Radnik, Jörg A1 - Rühle, Bastian A1 - Bresch, Harald T1 - Nanocarriers – Challenges Imposed by Material Characterization N2 - A brief perspective of BAM on nanocarriers is presented including examples with special emphasis on the characterization of such materials and underlying challenges. In this respect, also ongoing activities at BAM on different types of core/shell nanomaterials and related systems are briefly summarized. T2 - Kolloquium BfR CY - Online meeting DA - 18.03.2021 KW - Nanomaterial KW - Nanocarrier KW - Size KW - Surface chemistry KW - Release kinetics KW - Chemical composition KW - Core/shell nanoparticle KW - Quantum dot KW - Spectroscopy KW - Fluorescence PY - 2021 AN - OPUS4-52412 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin A1 - Dietrich, Paul M. A1 - Radnik, Jörg T1 - The change of DNA AND PROTEIN radiation damage upon hydration: In-situ observations by near-ambient-pressure XPS N2 - X-ray photoelectron-spectroscopy (XPS) allows simultaneous irradiation and damage monitoring. Although water radiolysis is essential for radiation damage, all previous XPS studies were performed in vacuum. Here we present near-ambient-pressure XPS experiments to directly measure DNA damage under water atmosphere. They permit in-situ monitoring of the effects of radicals on fully hydrated double-stranded DNA. Our results allow us to distinguish direct damage, by photons and secondary low-energy electrons (LEE), from damage by hydroxyl radicals or hydration induced modifications of damage pathways. The exposure of dry DNA to x-rays leads to strand-breaks at the sugar-phosphate backbone, while deoxyribose and nucleobases are less affected. In contrast, a strong increase of DNA damage is observed in water, where OH-radicals are produced. In consequence, base damage and base release become predominant, even though the number of strand-breaks increases further. T2 - Dyson Conference 2023 CY - Prague, Czech Republic DA - 24.04.2023 KW - Base damage KW - Base loss KW - Cancer treatment KW - DNA KW - DNA radiation damage KW - Direct damage KW - Dissociative electron attachment (DEA) KW - Dissociative electron transfer (DET) KW - Dosimetry KW - Double-strand break (DSB) KW - ESCA KW - Energy deposit KW - Geant4 KW - Geant4-DNA KW - Hydrated DNA KW - Hydrated electron KW - Hydration shell KW - Hydroxyl radical KW - Indirect damage KW - Ionization KW - Ionisation KW - LEE KW - Low energy electrons KW - MCS KW - Microdosimetry KW - NAP-XPS KW - Near ambient pressure xray photo electron spectroscopy KW - Net-ionization reaction KW - OH radical KW - PES KW - Particle scattering KW - Prehydrated electron KW - Presolvated electron KW - Quasi-direct damage KW - ROS KW - Radiation damage KW - Radiation therapy KW - Radical KW - Radiolysis KW - Radiotherapy KW - Reactive oxygen species KW - Simulation KW - Single-strand break (SSB) KW - TOPAS KW - TOPAS-nbio KW - XPS KW - Xray KW - Xray photo electron spectrocopy KW - G5P KW - Protein KW - Single-stranded DNA-binding proteins PY - 2023 AN - OPUS4-57406 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Radnik, Jörg A1 - Chemello, Giovanni A1 - Hodoroaba, Vasile-Dan T1 - VAMAS ILC of functionalized Graphene by XPS and Graphene Oxide by SEM N2 - The ideas of the planned VAMAS interlaboratory comparisons of functionalized graphene and graphene oxide are presented. T2 - Stakeholder Advisory Board ISO-G-Scope CY - Online meeting DA - 12.01.2022 KW - Graphene KW - XPS KW - SEM PY - 2022 AN - OPUS4-54375 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sachse, René A1 - Pflüger, Mika A1 - Velasco-Vélez, Juan-Jesús A1 - Sahre, Mario A1 - Radnik, Jörg A1 - Bernicke, Michael A1 - Bernsmeier, Denis A1 - Hodoroaba, Vasile-Dan A1 - Krumrey, Michael A1 - Strasser, Peter A1 - Kraehnert, Ralph A1 - Hertwig, Andreas T1 - Operando electrochemical spectroscopic ellipsometry: Material properties of highly active mesoporous IrOx films revealed under realistic OER conditions N2 - Hydrogen production via water electrolysis will be an essential cornerstone in development of sustainable, fossil-free fuel and chemical production on a global scale. The activity and stability of each catalyst is highly dependent on the properties of the coating, i.e., phase composition, crystallinity, accessible surface area, and many other factors. The key to developing improved catalysts is a better understanding of the relationships between their performance, stability, and physicochemical properties. However, these relationships can be complex and are also strongly influenced by the reaction environment. Therefore, operando analysis of the catalyst material during catalysis at realistic potentials and current densities is highly desirable. However, many analytical techniques cannot be applied in liquid environments at realistic potentials and current densities. We propose environmental ellipsometric analysis in a dedicated electrochemical flow cell as a method to evaluate gas evolution reactions operando under realistic working conditions. Figure 1 illustrates schematically the developed technique. Key factors to success are highly active model-type catalysts, a suitable sample environment, and a deep understanding of the appropriate model development, as well as concise cross validation with numerous other analytical techniques. The method was developed and validated by analyzing a calcination series (300 – 600 °C) of mesoporous templated IrOx films ex-situ and operando under oxygen evolution reaction (OER) conditions. The employed environmental electrochemical spectroscopic ellipsometric (ECSE) analysis revealed during OER the change of optical and electronic properties, i.e. the dielectric functions, resistivity and band-to-band transitions (p-d band transitions). Film thickness and porosity were validated by means of scanning electron microscopy (SEM), X-ray reflectometry (XRR) or ellipsometric porosimetry (EP), electrical and electronic properties by means of conductivity measurements, X-ray photoelectron spectroscopy (XPS) or UV-Vis-NIR absorption spectroscopy. The electronic structures of the catalysts from valence electron energy loss spectra (VEELS) derived from ε1 and ε2 from SE measurements reveal a direct correlation with electrochemical activities in OER. In the presentation reversible and irreversible potential-dependent changes of the catalyst properties during operation will be discussed along with the dynamics of gas formation, transport and dissolution at different potentials. T2 - 11th Workshop Ellipsometry (WSE 11) CY - Steyr, Austria DA - 06.09.2021 KW - Ectrocatalysis KW - Mesoporous iridium oxide films KW - Non-destructive operando analysis KW - Oxygen evolution reaction KW - Spectroscopic ellipsometry PY - 2021 AN - OPUS4-53915 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Radnik, Jörg A1 - Chemello, Giovanni A1 - Hodoroaba, Vasile-Dan A1 - Howe, T. A1 - Vyas, N. A1 - Reed, B. P. A1 - Pollard, A. J. A1 - Clifford, C. A. T1 - Reliable Chemical Characterization Protocols for Industrial Graphene-Related Materials N2 - Since its isolation, graphene has received growing attention from academia and industry due to its unique properties. Promising opportunities for applications are discussed in different field like electronics and optoelectronics, detection, and sensing devices, biosystems or chemical and environmental corrosion inhibition. Here, functionalization with elements like oxygen, nitrogen or fluorine can broaden the application, for example in composite materials. However, lack of generally accepted operation procedures hinders the commercialization, the so-called “what is my material” barrier. Therefore, first efforts were done to develop common, reliable, and reproducible ways to characterize the morphological and chemical properties of the industrially produced material. In this contribution, our efforts in the development of reliable chemical characterizations protocols for functionalized graphene are presented. An ISO standard for the chemical characterization of graphene-related (GRM) is under development with X-ray photoelectron spectroscopy (XPS) having a prominent role. With its information depth of around 10 nm, which is the similar length scale as the thickness of particles of 2D materials consisting of a few monolayers, XPS seems to be highly suitable for the quantitative analysis of (functionalized) GRM. Thereby, different sample preparation methods like pressing the powders onto adhesive tapes, into recesses, or into solid pellets result in inconsistencies in the quantification. Furthermore, different morphologies like stacks of graphene layers (left figure) or irregular particles (right figure) lead to different analysis results for the chemical composition. For the validation of the quantification with XPS and the further development of standards an international interlaboratory comparison was initiated under the head of the “Versailles Project on Advanced Materials and Standards” (VAMAS). First results are reported showing the suitability of the protocols. Finally, the XPS results are compared with the elemental composition results obtained after quantification with energy-dispersive X-ray spectroscopy (EDS) as a fast analytical method which is usually combined with electron microscopy. T2 - nanoSAFE 2023 CY - Grenoble, France DA - 05.06.2023 KW - X-ray photoelectron spectroscopy KW - Functionalized graphene KW - Interlaboratory comparison KW - VAMAS PY - 2023 AN - OPUS4-57652 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Radnik, Jörg A1 - Chemello, Giovanni A1 - Hodoroaba, Vasile-Dan A1 - Howe, T. A1 - Vyas, N. A1 - Reed, B.P. A1 - Pollard, A.J. A1 - Clifford, C.A. T1 - Reliable chemical characterization of industrial graphene related materials N2 - International standards describing reliable protocols will facilitate the commercialization of graphene and related 2D materials. One physico-chemical key property next to flake size and thickness is the chemical composition of the material. Therefore, an ISO standard is under development with X-ray photoelectron spectroscopy having a prominent role. With its information depth of around 10 nm which is the similar length scale as the thickness as of particles of 2D materials consisting of a few monolayer XPS seems to be highly suitable for this purpose. Different sample preparation methods like pressing the powders onto adhesive tapes, into recesses, or into solid pellets result in inconsistencies in the quantification. For the validation of the quantification with XPS an interlaboratory comparison was initiated under the auspice of the “Versailles Project on Advanced Materials and Standards” (VAMAS). First results confirm that the sample preparation method (pellet vs. powder) influences the quantification results clearly. Considering this effect, a good agreement of the results from the different participants were observed. Similar results were observed for raw, N- and F-functionalized graphene. T2 - Graphene CY - Manchester, England, UK DA - 27.06.2023 KW - X-ray photoelectron spectroscopy KW - Functionalized graphene KW - Interlaboratory comparison KW - VAMAS PY - 2023 AN - OPUS4-57895 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hodoroaba, Vasile-Dan A1 - Radnik, Jörg T1 - Minimale Anforderungen an Referenzdaten anhand von Beispielen aus der Elektronenmikroskopie und Oberflächenanalytik N2 - In dem Vortrag werden, anhand ausgewählten Beispielen aus der Elektronenmikroskopie und Oberflächenanalytik (EDX und XPS), die minimalen Anforderungen an Referenzdaten für zuverlässige und reproduzierbare Ergebnisse (z.B. Partikelgrößenverteilung, Elementzusammensetzung) vorgestellt und diskutiert. T2 - Workshop "Referenzdaten" CY - Berlin, Germany DA - 13.03.2020 KW - Referenzdaten KW - Nanopartikel KW - Elektronenmikroskopie KW - Oberflächenanalytik KW - Standardarbeitsanweisung KW - SOP KW - Standardisierung PY - 2020 AN - OPUS4-50571 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Quantifizierung der Schädigung von DNA in wässriger Lösung unter direkter Elektronenbestrahlung N2 - To cure cancer radiation therapy is used to kill tumor cells. It is based on radiation induced damage to biomolecules. Especially DNA damage is of key interest due to its central role in apoptosis and mutation. Because of the high amount of water in biological tissue, most of the damage is caused by the secondary particles produced by the inelastic scattering of ionizing radiation and water. A detailed understanding of the underlying molecular processes under physiological conditions is the prerequisite to develop more efficient therapies. Goal of this work is to quantify the DNA damage caused by ionizing radiation in dependence of the inelastic scattering events and the energy deposit within the microscopic target volume of biological relevance. The irradiations have to be performed in liquid, under consideration of the chemical environment. Therefore, a new combination of experiment and Monte-Carlo simulations was developed and tested. To make it possible to irradiate liquids with electrons within scanning electron microscopes a new sample holder was constructed incorporating an electron transparent nanomembrane. It makes it possible to irradiate DNA, proteins or cells at different pH, salinity and in the presence of cosolutes. %The most important results of this work are as follows: The median lethal dose for a model system of plasmid DNA and water was determined by the combination of experimental data, particle scattering simulations (Geant4-DNA) and diffusion calculations as D0.5=(1.7+-0.3) Gy. From the convolution of plasmid positions and the spatially resolved energy deposit, as determined by electron scattering simulations, the histogram of the energy deposit within the target volume of the plasmids and the microscopic median lethal energy deposit was calculated as E0.5=6+-4eV. It could be deduced that on average less than two ionization events are sufficient to cause a single-strand-break. The relation of single-strand-breaks (SSB) to double-strand-breaks (DSB), which is of importance for microdosimetric modeling, was determined as SSB:DSB = 12:1. The presented method for the determination of microscopic dose-damage relations was further extended to be applicable for general irradiation experiments. It becomes independent of the type of primary radiation used, the experimental geometry, and the diffusional properties of the molecules under investigation. This way different experimental systems with varying, inhomogeneous energy deposit characteristics become comparable with each other, which is not possible when only macroscopic averaged values are taken into account. In addition, the radiation protection properties of the compatible solute ectoine, as well as its influence on the water properties and biomolecules were investigated. %In addition, the influence of the compatible solute ectoine on water, biomolecules and its radiation protection properties were investigated. Raman spectroscopy revealed a concentration dependent increase of the collective water modes in the OH-stretching region, which was found to be independent of the sodium chloride concentration. Molecular dynamic simulations showed that the zwitterionic properties of ectoine lead to its half-chair conformation. The hydrogen bonds in the first hydration shell are more stable and have an increased lifetime compared to the bulk water. Irradiation experiments with DNA in the presence of 1M ectoine revealed an increase of the survival rate by a factor of 1.41 as compared to the absence of ectoine. The protective properties of ectoine result from the increase of the inelastic scattering probabilities of low energy electrons at the acoustic vibrational modes of water and its properties as OH-radical scavenger. This was shown by Raman spectroscopy and electron paramagnetic resonance measurements (EPR). T2 - Vortrag CY - Freie Universität Berlin, Germany DA - 14.02.2018 KW - DNA KW - Radiation damage KW - Ionizing radiation KW - DNA strand break KW - Dosimetry KW - Microdosimetry KW - Ectoine KW - Ectoine radiation protection KW - Salt KW - Water PY - 2018 AN - OPUS4-44280 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Radnik, Jörg T1 - Photoelectron spectroscopy N2 - A short introduction into the basics of Photoelectron Spectroscopy with the focus on surface sensitivity and applications is presented. T2 - Industrietreffen im Forschungs- und Innovationszentrum (FIZ) der BMW Group CY - Munich, Germany DA - 09.01.2018 KW - XPS KW - ESCA KW - Surface analytics PY - 2018 AN - OPUS4-43737 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin A1 - Sturm, Heinz A1 - Solomun, Tihomir T1 - Bestimmung des mikroskopischen Energiedeposits an DNA in komplexen Geometrien N2 - Mikrodosimetrie zum Einsatz in der Charakterisierung von per 3D Druck erstellen medizinischen Röntgenphantomen. T2 - Charite PhantomX CY - Charite Campus Berlin, Germany DA - 21.03.2018 KW - Dosimetrie KW - Phantome KW - Strahlentherapie KW - Computertomographie KW - Medizintechnik KW - Geant4 KW - Monte-Carlo Simulationen PY - 2018 AN - OPUS4-44564 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Radnik, Jörg A1 - Kersting, R. A1 - Hagenhoff, B. A1 - Bennett, Francesca A1 - Ciornii, Dmitri A1 - Hodoroaba, Vasile-Dan T1 - Comprehensive characterization of Al-coated titania nanoparticles with electron microscopy and surface chemical analytics N2 - The wide use of nanoforms with at least one dimension below 100 nm in our daily life requires a detailed knowledge of their physicochemical properties which are needed for risk assessment or quality control. Therefore, a comprehensive characterization of these properties was considered as relevant including: chemical composition, crystallinity, particle size, particle shape, surface chemistry, and specific surface area (SSA). We want to discuss, how Scanning Electron Microscopy (SEM), Electron Probe Microanalysis (EPMA) in the version with energy dispersive X-ray spectroscopy (EDS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and X-ray Photoelectron Spectroscopy (XPS) can contribute to gain comprehensive insights into the nature of the nanoparticles. SEM results provide the particle size and shape (distribution). A quick identification of the main chemical elements present in the sample can be obtained with EDS, whereas XPS allows a more detailed chemical identification of the small nanoparticles below 20 nm or of the near-surface region of larger particles. ToF-SIMS is even much more surface-sensitive and leads to a deeper understanding of the surface chemistry of the nanoparticles. As exemplary samples, two Al-coated TiO2 samples in nanopowder form were chosen from the JRC repository, capped either with a hydrophilic or a hydrophobic organic shell. A focus of our case study was to show, how reliable, reproducible and traceable data can be obtained. Therefore, each step in the workflow of sample investigation must be described in detail. For the most of these steps, well-established standards are available. Usually, the conditions of the particular measurements with each analysis method are saved as meta-data in the common file formats. But other factors like sample preparation and data reduction approaches may influence the result of the investigations in a significant manner and must be described often in a separate file (as a protocol) together with the data file. For sensitive materials like nanoobjects, the preparation of the sample influences the results crucially, e.g. measured as suspension or as powders. Furthermore, data reduction like selection of relevant peaks in spectra or particles in images, background subtraction, peak deconvolution, models for the quantification of the spectra must be considered in the interpretation of the results ideally with associated individual measurement uncertainties. Only a detailed description of all these factors allows to obtain a comprehensive characterization with reliable, reproduceable and traceable data. Examples of standardized procedures of measurement or on data reduction will be highlighted. We thank for the funding from the European Unions’s Horizon 2020 for the project NanoSolveIt (grant agreement No. 814572) and for the project NANORIGO (grant agreement No. 814530). T2 - E-MRS Spring Meeting CY - Online meeting DA - 31.05.2021 KW - Scanning Electron Microscopy KW - Energy dispersive X-ray spectroscopy KW - Time-of-Flight Secondary Ion Mass Spectrometry KW - X-ray Photoelectron Spectroscopy KW - Titania nanoparticles PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527486 AN - OPUS4-52748 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Panne, Ulrich A1 - Gornushkin, Igor B. A1 - Riedel, Jens A1 - Schneider, Rudolf A1 - Emmerling, Franziska T1 - "Keine Dienstmagd" - Analytical Sciences in Action N2 - Analytical Sciences has developed from Ostwald’s “unentbehrlichen Dienstmagd” to a chemical discipline at the core of many of today’s fundamental and applied scientific problems and innovations. An atomic or molecular understanding of basic processes in chemistry, soft matter physics, materials and life science is enabled only through new analytical methods and instrumentation. Similar observations can be found for pressing sociopolitical conflicts of the future: A rational discussion of global climate change or new energy sources is only possible with reliable analytical results. Progress in Analytical Sciences is only possible if the underlying interdisciplinary character is acknowledged and valued. The talk will illustrate the scope of modern Analytical Science through examples from process analysis relevant to modern process intensification and industry 4.0 to bioanalysis and the use of synchrotron radiation to elucidate fundamental reactions materials. T2 - MChG Talk CY - Technische Universität München, Germany DA - 27.11.2018 KW - Analytical Sciences PY - 2018 AN - OPUS4-46940 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Wolfgang A1 - Müller, Anja A1 - Heinrich, Thomas A1 - Kunz, Valentin A1 - Nymark, P. A1 - Radnik, Jörg T1 - Chemical characterization of nanoparticles by PCA-assisted ToF-SIMS: a) Core-shell character, b) transformation and c) grouping studies N2 - This talk was given within the scope of the SIMS-22 conference in October 2019 in Kyoto (Japan). It deals with the surface analytical investigation of nanoparticles by PCS-assisted ToF-SIMS. This technique is applicable to core-shell nanoparticles, in order to distinguish a complete encapsulation from an incomplete encapsulation of the core by the shell material. Furthermore, the depletion process of organic nanoparticle coatings caused by UV-weathering is investigated. Finally, the significance of grouping studies for nanomaterials research and risk assessment is demonstrated. T2 - The 22nd International Conference on Secondary Ion Mass Spectrometry (SIMS-22) CY - Kyoto, Japan DA - 20.10.2019 KW - Nanoparticles KW - ToF-SIMS KW - Principal component analysis (PCA) PY - 2019 AN - OPUS4-50075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -