TY - CONF A1 - Unger, Wolfgang T1 - 2-D materials standardization N2 - The implementation of new 2-D materials based technologies in production processes requires the development of quality management tools. These have to be underpinned by appropriate measurements. Consequently there is a need for the development of the metrology for measurement methods, the development of certified reference materials (CRM) and finally standardization. This chain represents the ideal way to practically useful standards. The presentation will give an overview on the main players in the field and summarize the recent status of activities. At the highest level the metrology of chemical characterization of 2D materials is in the scope of the International Meter Convention, specifically the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM). Pre-standardization is an activity field of the Versailles Project on Advanced Materials and Standards (VAMAS). Standardization is mainly addressed by addressed ISO Technical Committees. A summary on available CRMs relevant to the characterization of nano materials has been prepared by BAM. Examples from the work of BAM’s Division 6.1 “Surface Analysis and Interfacial Chemistry” showcasing the characterization of chemically modified graphene surfaces are given and specific needs for the development of metrology are addressed. In the discussion the audience is invited to define specific needs which will be streamlined to the respective bodies! T2 - Science-Industry-Workshop 2D Materials CY - EMPA Akademie, Dübendorf, Switzerland DA - 21.3.16 KW - Standardization KW - Graphene PY - 2016 AN - OPUS4-35866 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Wolfgang A1 - Stockmann, Jörg M. A1 - Senoner, Mathias A1 - Weimann, T. A1 - Bütefisch, S. A1 - Passiu, C. A1 - Spencer, N. D. A1 - Rossi, A. T1 - Introduction to lateral resolution and analysis area measurements in XPS N2 - Imaging and small-spot (small area) XPS have become increasingly important components of surface chemical analysis during the last three decades, and its use is growing. Some ambiguity in the use of terminology, understanding of concepts, and lack of appropriate reference materials leads to confusing and not always reproducible data. In this paper, it is shown that by using existing knowledge, appropriate test specimens, and standardized approaches, problems of comparability and such reproducibility issues recently observed for XPS data reported in the scientific literature can be overcome. The standardized methods of ISO 18516:2019, (i) the straight-edge, (ii) the narrow-line, and (iii) the grating method, can be used to characterize and compare the lateral resolution achieved by imaging XPS instruments and are described by reporting examples. The respective measurements are made using new test specimens. When running an XPS instrument in the small-spot (small area) mode for a quantitative analysis of a feature of interest, the question arises as to what contribution to the intensity originates from outside the analysis area. A valid measurement approach to control the intensity from outside the nominal analysis area is also described. As always, the relevant resolution depends on the specific question that needs to be addressed. The strengths and limitations of methods defining resolution are indicated. KW - Imaging XPS KW - Lateral resolution KW - Analysis area measurements KW - Small-spot XPS PY - 2020 DO - https://doi.org/10.1116/6.0000398 VL - 38 IS - 5 SP - 053206 AN - OPUS4-51394 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Häusler, Ines A1 - Dörfel, Ilona A1 - Peplinski, Burkhard A1 - Dietrich, Paul A1 - Unger, Wolfgang A1 - Österle, Werner T1 - Comprehensive characterization of ball-milled powders simulating a tribofilm system N2 - A model system was used to simulate the properties of tribofilms which form during automotive braking. The model system was prepared by ball milling of a blend of 70 vol.% iron oxides, 15 vol.% molybdenum disulfide and 15 vol.% graphite. The resulting mixture was characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and various transmission electron microscopic (TEM) methods, including energy dispersive X-ray spectroscopy (EDXS), high resolution investigations (HRTEM) with corresponding simulation of the HRTEM images, diffraction methods such as scanning nano-beam electron diffraction (SNBED) and selected area electron diffraction (SAED). It could be shown that the ball milling caused a reduction of the grain size of the initial components to the nanometer range. Sometimes even amorphization or partial break-down of the crystal structure was observed for MoS2 and graphite. Moreover, chemical reactions lead to a formation of surface coverings of the nanoparticles by amorphous material, molybdenum oxides, and iron sulfates as derived from XPS. KW - Tribofilm model system KW - Ball milling KW - X-ray powder diffraction KW - Transmission electron microscopy PY - 2016 DO - https://doi.org/10.1016/j.matchar.2015.11.024 SN - 1044-5803 SN - 1873-4189 VL - 111 SP - 183 EP - 192 PB - Elsevier CY - New York, NY AN - OPUS4-35051 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hentrich, D. A1 - Taabache, Soraya A1 - Brezesinski, G. A1 - Lange, Nele A1 - Unger, Wolfgang A1 - Kübel, C. A1 - Bertin, Annabelle A1 - Taubert, A. T1 - A dendritic amphiphile for efficient control of biomimetic calcium phosphate mineralization N2 - The phase behavior of a dendritic amphiphile containing a Newkome-type dendron as the hydrophilic moiety and a cholesterol unit as the hydrophobic segment is investigated at the air–liquid interface. The amphiphile forms stable monomolecular films at the air–liquid interface on different subphases. Furthermore, the mineralization of calcium Phosphate beneath the monolayer at different calcium and phosphate concentrations versus mineralization time shows that at low calcium and Phosphate concentrations needles form, whereas flakes and spheres dominate at higher concentrations. Energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and electron diffraction confirm the formation of calcium phosphate. High-resolution transmission electron microscopy and electron diffraction confirm the predominant formation of octacalcium phosphate and hydroxyapatite. The data also indicate that the final products form via a complex multistep reaction, including an association step, where nano-needles aggregate into larger flake-like objects. KW - Dendritic amphiphile KW - Calcium phosphate KW - Biomineralization PY - 2017 DO - https://doi.org/10.1002/mabi.201600524 SN - 1616-5187 SN - 1616-5195 VL - 17 IS - 8 SP - Article 1600524, 1 EP - 14 AN - OPUS4-41825 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kjaervik, Marit A1 - Schwibbert, Karin A1 - Dietrich, P.M. A1 - Unger, Wolfgang T1 - NAP-XPS spectra of the bacterial cell-envelope of Pseudomonas fluorescens bacteria N2 - Pseudomonas fluorescens (Gram-negative) bacteria purchased from Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures were analyzed using high-resolution x-ray photoelectron spectroscopy at near ambient pressure conditions (NAP-XPS), 1500 Pa water vapor atmosphere. Fresh layers of P. fluorescence bacteria were grown on Luria Broth agar plates. Bacteria were taken from the agar plate with a sterile spatula and gently spread on a Si-wafer piece for NAP-XPS analysis. The NAP-XPS spectra of the bacterial envelope of P. fluorescence were obtained using monochromatic Al Kα radiation and include a survey scan and high-resolution spectra of C 1s, N 1s, P 2p, and O 1s as well. The presentation of the C 1s high-resolution spectrum includes the results of peak fitting analysis. KW - Pseudomonas fluorescens KW - Cell-envelope KW - Water atmosphere KW - Near ambient x-ray photoelectron spectroscopy KW - NAP-XPS PY - 2022 DO - https://doi.org/10.1116/6.0001543 SN - 1055-5269 VL - 29 IS - 1 SP - 014008-1 PB - AVS AN - OPUS4-54464 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kulka, M. W. A1 - Donskyi, Ievgen A1 - Wurzler, Nina A1 - Salz, D. A1 - Özcan Sandikcioglu, Özlem A1 - Unger, Wolfgang A1 - Haag, R. T1 - Mussel-Inspired Multivalent Linear Polyglycerol Coatings Outperform Monovalent Polyethylene Glycol Coatings in Antifouling Surface Properties N2 - Biofouling constitutes a major challenge in the application of biosensors and biomedical implants, as well as for (food) packaging and marine equipment. In this work, an antifouling surface coating based on the combination of mussel-inspired dendritic polyglycerol (MI-dPG) and an amine-functionalized block copolymer of linear polyglycerol (lPG−b−OA11, OA = oligo-amine) was developed. The coating was compared to a MI-dPG surface which was postfunctionalized with commercially available amine-terminated Polyethylene glycol (HO−PEG−NH2) of similar molecular weight. In the current work, These coatings were compared in their chemical stability, protein fouling characteristics, and cell fouling characteristics. The lPG−b−OA11-functionalized coating showed high chemical stability in both phosphate buffered saline (PBS) and sodium dodecyl sulfate (SDS) solutions and reduced the adhesion of fibrinogen from human plasma with 99% and the adhesion of human serum albumin with 96%, in comparison to the bare titanium dioxide substrate. Furthermore, the Proliferation of human umbilical vein endothelial cells (HUVECs) was reduced with 85% when the lPG−b−OA11 system was compared to bare titanium dioxide. Additionally, a reduction of 94% was observed when the lPG−b−OA11 system was compared to tissue culture polystyrene. KW - Antifouling surface coatings KW - Human umbilical cell adhesion KW - Linear polyglycerol KW - Polyethylene glycol KW - Mussel-inspired adhesives PY - 2019 DO - https://doi.org/10.1021/acsabm.9b00786 VL - 2 IS - 12 SP - 5749 EP - 5759 PB - ACS AN - OPUS4-50342 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sobol, Oded A1 - Holzlechner, Gerald A1 - Holzweber, Markus A1 - Lohninger, H. A1 - Böllinghaus, Thomas A1 - Unger, Wolfgang T1 - First use of data fusion and multivariate analysis of ToF-SIMS and SEM image data for studying deuterium-assisted degradation processes in duplex steels N2 - Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and high-resolution scanning electron microscopy are well-acknowledged tools in materials characterization. The ability to map chemical species on the surface of an investigated sample with often low mass detection limits makes ToF-SIMS an essential tool in fields where many question marks concerning Degradation processes and damage mechanisms exist. The aim of this paper is to describe the power of data fusion of ToF-SIMS and high-resolution scanning electron microscopy results employing computational methods for multivariate data Analysis such as principal component analysis. As a case study the investigation of hydrogen distribution in an artificially charged Duplex stainless steel microstructure is presented aiming on a better understanding of hydrogen embrittlement. T2 - 16th European Conference on Applications of Surface and Interface Analysis CY - Granada, Spain DA - 28.09.2015 KW - ToF-SIMS KW - HR-SEM KW - Data fusion KW - Duplex stainless steel KW - Hydrogen embrittlement PY - 2016 UR - http://onlinelibrary.wiley.com/doi/10.1002/sia.6015/full DO - https://doi.org/10.1002/sia.6015 VL - 48 IS - 7 SP - 474 EP - 478 PB - John Wiley & Sons, Ltd CY - Surface and Interface Analysis AN - OPUS4-36832 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Silverstein, R. A1 - Sobol, Oded A1 - Böllinghaus, Thomas A1 - Unger, Wolfgang A1 - Eliezer, D. T1 - Hydrogen behavior in SAF 2205 duplex stainless steel N2 - This paper describes austenitic-ferritic duplex stainless steels, SAF 2205, in the presence of hydrogen. The duplex stainless steels (DSS) properties include excellent resistance to stress corrosion cracking, high strength and good weldability. Those steels are preferably used in industries combining hydrogen and loads. Hydrogen location in addition to hydrogen binding energy with the steel's defects are of great importance for the analysis of hydrogen embrittlement model in that steel. It is known from previously published works that the susceptibility to hydrogen embrittlement will depend on the competition between reversible and irreversible traps; meaning a direct relation to the hydrogen's state and position in the steel. In this work, we examine the local hydrogen concentration, trapping and distribution by two modern and advanced techniques: thermal desorption spectrometry (TDS) and we support it by time of flight-secondary ion mass spectrometer (ToF-SIMS). In this paper, we support and give for the first time new insights and better understanding to the hydrogen embrittlement mechanism in SAF 2205. The trapping energies levels were calculated using TDS and Lee and Lee's model. This model revealed reversible in addition to irreversible trapping sites. Also the trapping controlling mechanism was found to be a combination of detrapping controlled mechanism and diffusion controlled mechanism. The use of ToF-SIMS for local imaging the distribution of hydrogen species supports the discussion of the different hydrogen traps in this type of steel. The hydrogen embrittlemet phenomenon in SAF 2205 will be discussed in details in that paper. KW - Hydrogen trapping KW - Duplex stainless steel KW - Thermal desorption spectrometry (TDS) KW - ToF-SIMS PY - 2017 DO - https://doi.org/10.1016/j.jallcom.2016.11.184 SN - 0925-8388 SN - 1873-4669 VL - 695 SP - 2689 EP - 2695 PB - Elsevier B.V. AN - OPUS4-38856 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sobol, Oded A1 - Böllinghaus, Thomas A1 - Wirth, Thomas A1 - Unger, Wolfgang A1 - Eliezer, D. T1 - High resolution ToF-SIMS imaging of deuterium permeation and cracking in duplex stainless steels N2 - Fundamental understanding and elucidation of hydrogen assisted degradation and trapping mechanisms is dependent on sufficient imaging techniques for respective hydrogen interactions, in particular with multi-phase metallic microstructures. The present work shows the progress in elucidating the deuterium behavior in austenitic-ferritic duplex stainless steels under the consideration that deuterium behaves in many ways similarly to hydrogen. A novel combination of deuterium permeation and in-situ Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) imaging technique is compared with post charging ToF-SIMS imaging experiments. As a step beyond state-of-the-art, integration of chemo-metric and high resolution structural characterization techniques with computational multivariate data analysis (MVA) and data fusion is presented. T2 - 2016 International Hydrogen Conference CY - Grand Teton National Park, Jackson Lake Lodge, Wyoming, USA DA - 11.09.2016 KW - DSS KW - ToF-SIMS KW - Data-fusion KW - EBSD PY - 2017 SN - 978-0-7918-6138-7 SP - 407 EP - 415 PB - ASME Press CY - Two Park Ave. New-York, NY 10016, USA AN - OPUS4-42647 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Röhsler, Andreas A1 - Sobol, Oded A1 - Nolze, Gert A1 - Unger, Wolfgang A1 - Böllinghaus, Thomas T1 - Use of time-of-flight secondary ion mass spectrometry for the investigation of hydrogen-induced effects in austenitic steel AISI 304L N2 - During the energy transformation from fossil fuels to renewable energy sources, the use of hydrogen as fuel and energy storage can play a key role. This presents new challenges to industry and the scientific community alike. The storage and transport of hydrogen, which is nowadays mainly realized by austenitic stainless steels, remains problematic, which is due to the degradation of mechanical properties and the possibility of phase transformation by hydrogen diffusion and accumulation. The development of materials and technologies requires a fundamental understanding of these degradation processes. Therefore, studying the behavior of hydrogen in austenitic steel contributes to an understanding of the damage processes, which is crucial for both life assessment and safe use of components in industry and transportation. As one of the few tools that is capable of depicting the distribution of hydrogen in steels, time-of-flight secondary ion mass spectrometry was conducted after electrochemical charging. To obtain further information about the structural composition and cracking behavior, electron-backscattered diffraction and scanning electron microscopy were performed. Gathered data of chemical composition and topography were treated employing data fusion, thus creating a comprehensive portrait of hydrogen-induced effects in the austenite grade AISI 304L. Specimens were electrochemically charged with deuterium instead of hydrogen. This arises from the difficulties to distinguish between artificially charged hydrogen and traces existing in the material or the rest gas in the analysis chamber. Similar diffusion and permeation behavior, as well as solubility, allow nonetheless to draw conclusions from the experiments. T2 - 21st International Conference on Secondary Ion Mass Spectrometry CY - Kraków, Poland DA - 10.09.2017 KW - AISI 304L KW - Hydrogen KW - ToF-SIMS KW - Austenitic stainless steel PY - 2018 DO - https://doi.org/10.1116/1.5013931 SN - 1071-1023 VL - 36 IS - 3 SP - Article 03F103, 1 EP - 6 PB - American Vacuum Society (AVS) AN - OPUS4-44840 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -