TY - JOUR A1 - Ehlert, Christopher A1 - Holzweber, Markus A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Saalfrank, Peter T1 - A detailed assignment of NEXAFS resonances of imidazolium based ionic liquids JF - Physical Chemistry Chemical Physics N2 - In Near Edge X-Ray Absorption Fine Structure (NEXAFS) spectroscopy X-Ray photons are used to excite tightly bound core electrons to low-lying unoccupied orbitals of the system. This technique offers insight into the electronic structure of the system as well as useful structural information. In this work, we apply NEXAFS to two kinds of imidazolium based ionic liquids ([CnC₁im]⁺[NTf₂]⁻ and [C₄C₁im]⁺[I]⁻). A combination of measurements and quantum chemical calculations of C K and N K NEXAFS resonances is presented. The simulations, based on the transition potential density functional theory method (TP-DFT), reproduce all characteristic features observed by the experiment. Furthermore, a detailed assignment of resonance features to excitation centers (carbon or nitrogen atoms) leads to a consistent interpretation of the spectra. KW - Ionic liquids KW - NEXAFS KW - DFT spectrum simulations PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-367223 DO - https://doi.org/10.1039/c5cp07434g SN - 1463-9076 SN - 1463-9084 VL - 18 IS - 12 SP - 8654 EP - 8661 PB - Royal Society of Chemistry CY - Cambridge, UK AN - OPUS4-36722 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Holzweber, Markus A1 - Hodoroaba, Vasile-Dan A1 - Lippitz, Andreas A1 - Hesse, R. A1 - Denecke, R. A1 - Unger, Wolfgang T1 - Ionische Flüssigkeiten als Referenzmaterial in der Oberflächenanalytik N2 - Die Bestimmung der chemischen Zusammensetzung einer Oberfläche und deren Quantifizierung mit wichtig für die Qualitätssicherung vieler industrieller Produkte und Materialien. Die chemische Beschaffenheit von Oberflächen bzw. Grenzflächen muss genau kontrolliert werden um die Produktqualität zu garantieren. Diese Prüfung ist oft auch für individuelle Prozessschritte durchzuführen. Referenzmaterialien sind unverzichtbar, wenn es darum geht, die Richtigkeit und Zuverlässigkeit von Messergebnissen zu gewährleisten. Falsche Messwerte können zu erheblichen Mehrkosten führen. Referenzmaterialien gewährleisten die Rückführung von Messergebnissen auf anerkannte Bezugsgrößen (Standards), dienen der Ermittlung der Messunsicherheit von analytischen Verfahren und wer-den zur Kalibrierung verwendet. Für zertifizierte/akkreditierte (ISO 9000 und ISO 17025) Prüf- und Kalibrierlaboratorien ist der Einsatz von Referenzmaterialien in der Qualitätssicherung obligatorisch. Ionischen Flüssigkeiten (IL) sind vielversprechende Kandidaten für die Verwendung als Referenzmaterial in oberflächenanalytischen Verfahren wie Energie-dispersive Röntgenspektroskopie (EDX) und Röntgenphotoelektronenspektroskopie (XPS). In zwei Machbarkeitsstudien wurde eine geeignete Klasse von ILs als Referenzmaterial getestet: Für die Anwendung in EDX wurde die Eignung von ILs als Referenzmaterial zur routinemäßigen Überprüfung der Energieskala, der Energieauflösung und der Spektrometer-Effizienz untersucht. Es kann gezeigt werden, dass mit einer einzigen Messung an einem einzigen Referenzmaterial mehrere Geräteparameter überprüft werden können. Damit ist es im niederenergetischen Bereich möglich, regelmäßige Funktionsprüfungen von Spektrometern durchzuführen, aber auch die Leistungsfähigkeit verschiedener Spektrometer zu vergleichen Für Die Anwendung in XPS wurde die Eignung von ILs als Referenzmaterial zur Bestimmung der Transmissionsfunktion T(E) von Photoelektronenspektrometern getestet. Dazu wurde die Auswertesoftware UNIFIT entsprechend adaptiert und erlaubt nun T(E) anhand der bekannten Stöchiometrie der IL zu ermitteln. Es wird gezeigt, dass durch die Verwendung ausgewählter ILs als Referenzmaterial die Genauigkeit der Quantifizierung von XPS Daten unter Nutzung einer experi-mentell bestimmten T(E) wesentlich verbessert werden kann. T2 - 19. Arbeitstagung Angewandte Oberflächenanalytik CY - Soest, Germany DA - 05-09-2016 KW - Ioniosche Flüssigkeiten KW - Referenzmaterial KW - REM-EDX KW - XPS PY - 2016 AN - OPUS4-37640 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Holzweber, Markus A1 - Nietzold, Carolin A1 - Dietrich, Paul A1 - Lippitz, Andreas A1 - Kamalakumar, A. A1 - Ivanov-Pankov, S. A1 - Blanchard, V. A1 - Weigel, W. A1 - Panne, Ulrich A1 - Unger, Wolfgang T1 - Surface chemical characterization and shelf life studies of reference glycan microarrays using ToF-SIMS, XPS and fluorescence spectroscopy N2 - Covalent modification of surfaces with carbohydrates (glycans) is a prerequisite for a variety of glycomics-based biomedical applications, including functional biomaterials, glycan-arrays, and glycan-based biosensors. The chemistry of glycan immobilization plays an essential role in the bioavailability and function of surface bound carbohydrate moieties. For biomedical applications the stability over time (shelf life) of a glycan-array is a crucial factor. Basic requirements for the production of microarrays are first of all stable signals without any loss of quality. Therefore, the investigation of the shelf life for carbohydrate microarrays is an important part in the development of glycan-arrays. Motivated by the need of reliable quality control for glycan microarrays, we developed reference arrays using fluorescent model glycans. Since the long term stability of glycan microarrays is a crucial factor for their clinical application the shelf life at different storage conditions of glycan microarrays was studied in detail using the two model glycan compounds. Herein, we present a shelf life study of model glycan microarrays on epoxy modified glass surfaces over a period of 320 days. This was carried out using different analyzing techniques such as Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), X-ray Photoelectron Spectroscopy (XPS) and Fluorescence Spectroscopy. To analyze and interpret the ToF-SIMS dataset the multivariate technique principal component analysis (PCA) was used. The dependence of the array´s shelf life upon storage conditions was specifically studied. T2 - SIMS Europe 2016 CY - Münster, Germany DA - 18.9.2016 KW - Glycan microarray KW - XPS KW - SIMS KW - Fluorescence spectroscopy PY - 2016 AN - OPUS4-37638 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Holzweber, Markus A1 - Sobol, Oded A1 - Wirth, Thomas A1 - Böllinghaus, Thomas A1 - Unger, Wolfgang T1 - Deuterium permeation and cracking in duplex steels as viewed by ToF-SIMS and HR-SEM with data fusion N2 - Better understanding of hydrogen assisted degradation and trapping mecha-nisms requires sufficient imaging techniques for respective hydrogen-microstructure interaction studies, in particular with multi-phase metallic micro-structures [1]. The present work is focusing on the elucidation of deuterium be-havior in two austenitic-ferritic duplex stainless steels (DSS) under the assumption that deuterium behaves in many ways similarly to hydrogen [2]. For case studies standard 2205 and lean 2101 DSSs were chosen due to the extensive use of these steels in industry [3]. The analyses were conducted by using a novel in-situ permeation and Time-of-Flight secondary ion mass spectrometry (ToF-SIMS) imaging technique or by ex-situ ToF-SIMS imaging following electrochemical charging experiments. Another pioneering procedure was data fusion (including chemometry) of results of powerful laterally resolved chemical analysis and high resolution structural characterization techniques . Results for the ex-situ observations showed a different influence of deuterium loading on the two steel grades as well as different damage mechanisms in each phase. Formation of sub-surface blisters between the ferrite and austenite were obtained in both the standard and the lean DSS. In both steels, an increased deuterium concentration was observed around deformed regions such as cracks, confirming that they originate from the presence of deuterium [4]. The formation of parallel cracks was obtained only in the austenite within the standard duplex whereas in the lean duplex the highest intensity of deuterium was obtained in the austenite along the ferrite-austenite interphase. In comparison, application of the novel in-situ permeation technique enabled to register and record the deuterium permeation through the material and the respective saturation sequence of the two phases as well as the interfaces. Faster diffusion of the deuterium was observed in the ferrite and a direct proof for deuterium enrichment at the austenite-ferrite interface has been given [1]. The integration of the specified techniques gives a better insight into the processes leading to hydrogen induced failure. These two experimental techniques provide very valuable tools for elucidation of respective metallurgical failure mechanisms that can be used for the validation of respective numerical models for hydrogen assisted cracking (HAC). T2 - 19. Arbeitstagung Angewandte Oberflächenanalytik CY - Soest, Germany DA - 05.09.2016 KW - ToF-SIMS KW - Hydrogen assisted cracking KW - Data fusion KW - SEM PY - 2016 AN - OPUS4-37484 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Holzweber, Markus A1 - Unger, Wolfgang A1 - Hodoroaba, Vasile-Dan T1 - Ionic liquids as a reference material candidate for the quick performance check of energy dispersive X-ray spectrometers for the low energy range below 1 keV JF - Analytical Chemistry N2 - Ionic liquids (ILs) are proposed as simple and efficient test materials to evaluate the performance of energy dispersive X-ray spectrometers (EDS) in the low energy range below 1 keV. By only one measurement, C Kα, N Kα, O Kα, and F Kα X-ray lines can be excited. Additionally, the S Kα line at 2.3 keV and, particularly, the S L series at 149 eV complete the picture with X-ray lines offered by the selected ILs. The well-known (certifiable) elemental composition of the ILs selected in the present study can be used to check the accuracy of results produced with the available EDS quantification routines in the low energy range, simultaneously, for several low atomic number elements. A comparison with other reference materials in use for testing the performance of EDS in the low energy range is included. KW - Ionic liquids KW - EDX KW - CRM KW - Reference material KW - Low energy KW - X-rays PY - 2016 UR - http://pubs.acs.org/doi/abs/10.1021/acs.analchem.6b01444 DO - https://doi.org/10.1021/acs.analchem.6b01444 SN - 0003-2700 SN - 1520-6882 VL - 88 IS - 14 SP - 6967 EP - 6970 PB - ACS Publications CY - 1155 Sixteenth Street N.W., Washington, DC 20036 AN - OPUS4-36912 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ortel, Erik A1 - Häusler, Ines A1 - Österle, Werner A1 - Narbey, S. A1 - Oswald, F. A1 - Andersen, I. H. A1 - Holzweber, Markus A1 - Unger, Wolfgang A1 - Hodoroaba, Vasile-Dan T1 - In-depth structural and chemical characterization of engineered TiO2 films JF - Surface and Interface Analysis N2 - Analytical routines for a comprehensive in-depth morphological, structural, and chemical characterization of functionalized TiO2 films by using different state-of-the-art analytical techniques are presented and discussed with the main objective to identify potential reference TiO2 coating parameters able to be certified at a later stage. TiO2 films fabricated by two different synthetic procedures as representative for two main large-scale applications were selected: (i) pulsed d.c. magnetron sputtering for photocatalytic applications and (ii) screen printing from preformed anatase nanoparticles. The screen-printed films were further loaded with a sensitizing dye for application as a dye-sensitized solar cell. Film properties such as microstructure and crystallographic texture of pulsed d.c. magnetron sputtering synthesized films were systematically studied by means of scanning nanobeam electron diffraction in a transmission electron microscope and the surface and inner morphology by scanning electron microscopy. The dye distribution over the depth of screen-printed TiO2 layers was analyzed before and after dye-loading by means of energy dispersive X-ray spectroscopy at scanning electronmicroscope, Auger electron spectroscopy and time-of-flight secondary ion mass spectrometry. The long-term goal of the present study is the improvement of quality of the TiO2 film parameters as measured by using different types of reference TiO2 coatings having specific parameters certified. T2 - 16th European Conference on Applications of Surface and Interface Analysis ECASIA'15 CY - Granada, Spain DA - 28.09.2015 KW - Mapping KW - Line scan KW - Depth profiling KW - TiO2 films KW - Crystallinity KW - Ru dye sensitizer PY - 2016 DO - https://doi.org/10.1002/sia.5966 SN - 0142-2421 SN - 1096-9918 VL - 48 SP - 664 EP - 669 PB - John Wiley & Sons, Ltd. AN - OPUS4-36791 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 JF - ECASIA special issue paper 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 -