TY - JOUR A1 - Dietrich, Paul A1 - Hennig, Andreas A1 - Holzweber, Markus A1 - Thiele, T. A1 - Borcherding, H. A1 - Lippitz, Andreas A1 - Schedler, U. A1 - Resch-Genger, Ute A1 - Unger, Wolfgang T1 - Surface analytical study of poly(acrylic acid)-grafted microparticles (beads): characterization, chemical derivatization, and quantification of surface carboxyl groups N2 - We report a surface analytical study of poly(methyl methacrylate) (PMMA) microparticles (beads) with a grafted shell of poly(acrylic acid) (PAA) with thicknesses up to 4 nm using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and near-edge X-ray adsorption fine structure (NEXAFS) spectroscopy. These polymer microparticles were analyzed before and after reaction of the surface carboxyl (CO2H) groups with 2,2,2-trifluoroethylamine (TFEA) to gain a better understanding of methods with use of covalently bound probe molecules for surface group analysis. The results obtained with chemical derivatization XPS using TFEA are discussed in terms of surface quantification of reactive CO2H groups on these PAA-coated microparticles. A labeling yield of about 50% was found for TFEA-derivatized particles with amounts of surface-grafted CO2H groups of 99 µmol/g or more, which is consistent with predicted reaction yields for homogeneously dispersed PAA hydrogels. KW - Polymer microparticles KW - Poly(acrylic acid)-grafted microparticles KW - Beads KW - XPS KW - SEM KW - NEXAFS KW - Surface analysis KW - Fluorine labeling PY - 2014 DO - https://doi.org/10.1021/jp505519g SN - 1932-7447 SN - 1089-5639 VL - 118 IS - 35 SP - 20393 EP - 20404 PB - Soc. CY - Washington, DC AN - OPUS4-31326 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietrich, Paul A1 - Streeck, C. A1 - Glamsch, Stephan A1 - Ehlert, Christopher A1 - Lippitz, Andreas A1 - Nutsch, A. A1 - Kulak, N. A1 - Beckhoff, B. A1 - Unger, Wolfgang T1 - Quantification of silane molecules on oxidized silicon: Are there options for a traceable and absolute determination? N2 - Organosilanes are used routinely to functionalize various support materials for further modifications. Nevertheless, reliable quantitative information about surface functional group densities after layer formation is rarely available. Here, we present the analysis of thin organic nanolayers made from nitrogen containing silane molecules on naturally oxidized silicon wafers with reference-free total reflection X-ray fluorescence (TXRF) and X-ray photoelectron spectroscopy (XPS). An areic density of 2−4 silane molecules per nm2 was calculated from the layer’s nitrogen mass deposition per area unit obtained by reference-free TXRF. Complementary energy and angle-resolved XPS (ER/ARXPS) in the Si 2p core-level region was used to analyze the outermost surface region of the organic (silane layer)−inorganic (silicon wafer) interface. Different coexisting silicon species as silicon, native silicon oxide, and silane were identified and quantified. As a result of the presented proof-of-concept, absolute and traceable values for the areic density of silanes containing nitrogen as intrinsic marker are obtained by calibration of the XPS methods with reference-free TXRF. Furthermore, ER/AR-XPS is shown to facilitate the determination of areic densities in (mono)layers made from silanes having no heteroatomic marker other than silicon. After calibration with reference-free TXRF, these areic densities of silane molecules can be determined when using the XPS component intensity of the silane’s silicon atom. PY - 2015 DO - https://doi.org/10.1021/acs.analchem.5b02846 SN - 0003-2700 SN - 1520-6882 VL - 87 IS - 19 SP - 10117 EP - 10124 PB - American Chemical Society CY - Washington, DC AN - OPUS4-34796 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ortel, Erik A1 - Bernicke, M. A1 - Eckhardt, B. A1 - Bernsmeier, D. A1 - Schmack, R. A1 - Kraehnert, R. A1 - Lippitz, Andreas T1 - Synthesis and OER activity of NiO coatings with N2 - Catalysts based on nickel oxide are some of the most active catalysts for the oxygen evolution reaction (OER) in alkaline media. However, preparing catalytic coatings with high surface area and good accessibility of the active sites remains challenging. We present a new approach for the synthesis of homogeneous and binder-free nickel oxide coatings comprising a highly accessible ordered mesopore structure. The synthesis is achieved via evaporation induced self assembly utilizing PEOPB-PEO triblock copolymers as pore template and a chemical complex of Ni2+ and citric acid as precursor. Excessive crystallization behaviour of NiO is avoided by thermal conversion of the precursor into an amorphous Ni carbonate intermediate, followed by transition of the carbonate into the metal oxide. We present a comprehensive analysis of the obtained materials in terms of morphology, crystallinity, surface area, composition, and OER activity of differently calcined catalysts. Retaining a low crystallinity and high surface area during the Synthesis proofs to be the most important factor in obtaining a highly active OER catalyst. KW - XPS KW - nanoparticle KW - catalysis PY - 2016 UR - http://onlinelibrary.wiley.com/doi/10.1002/slct.201600110/abstract DO - https://doi.org/10.1002/slct.201600110 VL - 2016 IS - 3/2016 SP - 482 EP - 489 PB - Wiley Online Library CY - Weinheim AN - OPUS4-35725 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietrich, Paul A1 - Glamsch, Stephan A1 - Ehlert, Christopher A1 - Lippitz, Andreas A1 - Kulak, N. A1 - Unger, Wolfgang T1 - Synchrotron-radiation XPS analysis of ultra-thin silane films: Specifying the organic silicon N2 - The analysis of chemical and elemental in-depth variations in ultra-thin organic layers with thicknesses below 5 nm is very challenging. Energy- and angle-resolved XPS (ER/AR-XPS) opens up the possibility for non-destructive chemical ultra-shallow depth profiling of the outermost surface layer of ultra-thin organic films due to its exceptional surface sensitivity. For common organic materials a reliable chemical in-depth analysis with a lower limit of the XPS information depth z95 of about 1 nm can be performed. As a proof-of-principle example with relevance for industrial applications the ER/AR-XPS analysis of different organic monolayers made of amino- or benzamidosilane molecules on silicon oxide surfaces is presented. It is demonstrated how to use the Si 2p core-level region to non-destructively depth-profile the organic (silane monolayer) – inorganic (SiO2/Si) interface and how to quantify Si species, ranging from elemental silicon over native silicon oxide to the silane itself. The main advantage of the applied ER/AR-XPS method is the improved specification of organic from inorganic silicon components in Si 2p core-level spectra with exceptional low uncertainties compared to conventional laboratory XPS. KW - Synchrotron radiation XPS KW - Depth profiling KW - Silanes KW - Monolayer KW - Amines KW - Amides PY - 2016 DO - https://doi.org/10.1016/j.apsusc.2015.12.052 SN - 0169-4332 SN - 1873-5584 VL - 363 SP - 406 EP - 411 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-35262 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Hidde, Gundula A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Plasma bromination of graphene for covalent bonding of organic molecules N2 - Plasma-chemical bromination applied to graphitic materials, in particular to highly ordered pyrolytic graphite is reviewed. The resulting bromination efficiency of the plasma-chemical treatment was subject of systematic process optimization. The plasma of elemental bromine vapour produced bromine concentrations on graphene surfaces of more than 30 % Br/C using either inductively or capacitively coupled low-pressure radio-frequency plasmas. Plasma brominated graphite surfaces have been studied by Near Edge X-ray Absorption Fine Structure, X-ray Photoelectron Spectroscopy, Atomic Force Microscopy and Scanning Electron Microscopy. The introduction of bromine into graphene-like graphite layers and its binding situation were investigated. To study the physical effect of the plasma bromination process, Kr plasma was also used because of its chemical inertness but similar atomic mass. Covering the samples with a Faraday cage or with a LiF window should help to differentiate between physical, chemical and radiation effects of the plasma. Bromination was assigned to radical or electrophilic addition of bromine onto fully substituted aromatic double bonds (sp² C) with exothermal reaction enthalpy. Low bromination shows a strong decay of aromatic double bonds, higher bromination percentage let disappear all aromatic rings. The formed C–Br bonds were well suited for efficient grafting of organic molecules by post-plasma wet-chemical nucleophilic substitution. This grafting onto the graphene surface was demonstrated using aminosilane and different diamines. The bromination of double bonds changes the hybridization of carbon atoms from plane sp² to tetrahedral sp³ hybridization. Thus, the plane topography of graphene is destroyed and the conductivity is lost. KW - Graphene KW - Bromination KW - Grafting of diamines KW - Plasma KW - Organic graphting PY - 2014 DO - https://doi.org/10.1007/s11090-013-9509-x SN - 0272-4324 VL - 34 SP - 621 EP - 645 PB - Plenum Publ. Corp. CY - New York, NY, USA AN - OPUS4-30575 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nietzold, Carolin A1 - Dietrich, Paul A1 - Ivanov-Pankov, S. A1 - Lippitz, Andreas A1 - Gross, Thomas A1 - Weigel, W. A1 - Unger, Wolfgang T1 - Functional group quantification on epoxy surfaces by chemical derivatization (CD)-XPS N2 - In this study, epoxy-terminated silicon oxide surfaces were chemically derivatized with trifluoroacetic anhydride (TFAA) and 4-(trifluoromethyl)-benzylamine (TFMBA) and analyzed by X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy and water contact angle measurements. TFAA was used for quantitative derivatization to determine the amount of reactive epoxy groups on these surfaces. Furthermore, epoxy-terminated surfaces were derivatized with TFMBA (a model compound for biomolecules with an amino linker) yielding secondary amines because of formation of covalent C–N bonds between TFMBA and the epoxy films. Fluorine being part of TFAA and TFMBA composition was used to follow the progress of the chemical derivatization reaction. Both derivatization agents – TFAA and TFMBA – gave comparable reaction yields of ~60% on epoxy silicon surfaces, whereas on epoxy glass slides, the derivatization yields were considerably lower (30–40%).The protocol for attachment of TFMBA (model compound) on epoxy-modified surfaces was adapted to (bio)molecules with an amino linker, e.g. carbohydrates to prepare carbohydrate-functionalized biointerfaces. KW - Biomolecular interfaces KW - Epoxy-functionalized surfaces KW - CD-XPS KW - Functional group quantification KW - Contact angle measurements PY - 2014 DO - https://doi.org/10.1002/sia.5433 SN - 0142-2421 SN - 1096-9918 VL - 46 IS - 10-11 SP - 668 EP - 672 PB - Wiley CY - Chichester AN - OPUS4-31605 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Wolfgang A1 - Schwarz, F. A1 - Heinrich, Thomas A1 - Kaufmann, J. O. A1 - Lippitz, Andreas A1 - Puttreddy, R. A1 - Rissanen, K. A1 - Schalley, C. A. T1 - Photocontrolled on-surface pseudorotaxane formation with well-ordered macrocycle multilayers N2 - The photoinduced pseudorotaxane formation between a photoresponsive axle and a tetralactam macrocycle was investigated in solution and on glass surfaces with immobilized multilayers of macrocycles. In the course of this reaction, a novel photoswitchable binding station with azobenzene as the photoswitchable unit and diketopiperazine as the binding station was synthesized and studied by NMR and UV/Vis spectroscopy. Glass surfaces have been functionalized with pyridine-terminated SAMs and subsequently withmultilayers of macrocycles through layer-by-layer self assembly. A preferred orientation of the macrocycles could be confirmed by NEXAFS spectroscopy. The photocontrolled Deposition of the axle into the surface-bound macrocycle-multilayers was monitored by UV/Vis spectroscopy and led to an increase of the molecular order, as indicated by more substantial linear dichroism effects in angle-resolved NEXAFS spectra. KW - Well-ordered macrocycle multilayers KW - XPS KW - NEXAFS PY - 2016 DO - https://doi.org/10.1002/chem.201603156 SN - 0947-6539 SN - 1521-3765 VL - 22 IS - 40 SP - 14383 EP - 14389 PB - Wiley-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-38270 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lange, Nele A1 - Dietrich, Paul M. A1 - Lippitz, Andreas A1 - Kulak, N. A1 - Unger, Wolfgang T1 - New azidation methods for the functionalization of silicon nitride and application in copper-catalyzed azide-alkyne cycloaddition (CuAAC) N2 - In this study, a new direct functionalization method of silicon nitride (Si3N4) using azidation and click chemistry is presented. First, amino groups (NHx) were created on a Si3N4 substrate by fluoride etching. These NHx-terminated Si3N4 surfaces were analyzed by chemical derivatization X-ray photoelectron spectroscopy (CD-XPS) with 4-trifluoromethylbenzaldehyde (TFBA) and a derivatization yield of 20% was concluded. In the second step freshly prepared NHx surfaces were transformed into azides which were used immediately in a click reaction with halogenated alkynes. The presented combination of amination, azidation and click reaction is a promising alternative for common silane-based Si3N4 functionalization methods. T2 - 16th European Conference on Applications of Surface and Interface Analysis CY - Granada, Spain DA - 28.09.2015 KW - XPS KW - Azidation KW - Click chemistry KW - Silicon nitride KW - Chemical derivatization PY - 2016 UR - http://onlinelibrary.wiley.com/doi/10.1002/sia.5950/full DO - https://doi.org/10.1002/sia.5950 VL - 48 SP - 621 EP - 625 PB - John Wiley & Sons, Ltd AN - OPUS4-36841 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Khosravi, Z. A1 - Kotula, S. A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Klages, C.-P. T1 - IR- and NEXAFS-spectroscopic characterization of plasma-nitrogenated polyolefin surfaces N2 - Modification of polyethylene and polypropylene surfaces by atmospheric-pressure plasmas using mixtures of nitrogen and hydrogen was studied using Fouriertransform infrared spectroscopy in the attenuated total reflection mode (FTIR-ATR) and by near-edge x-ray absorption fine structure spectroscopy (NEXAFS) in order to shed some light on the chemical nature of nitrogen-containing functional Groups on the polymer surface. Using FTIR-ATR spectroscopy combined with hydrogendeuterium isotope exchange of active hydrogen atoms, it was shown that the direct treatment of PE foils by dielectric barrier discharges (DBDs) in N2/H2 mixtures and a subsequent exposure of the samples to the ambient air results in the formation of –NH2 moieties of primary amides on the polymer surface. Corresponding in situ experiments with streaming N2/H2 DBD post-discharges virtually free of H2O and O2, on the other hand, showing the absence of –NH2, proving that no primary amines or amides are formed by this treatment although substantial amounts of nitrogen are incorporated. Moreover, directly N2/H2-plasma-treated polymer surfaces, similar to afterglow-treated low-density polyethylene (LDPE), show amphiphilic character as to be seen by chemical derivatization with nucleophilic reagents 4-(trifluoromethyl) phenylhydrazine and 4-(trifluoromethyl)benzylamine, in addition to electrophilic aromatic aldehydes normally used to derivatize such surfaces. The presence of imines or other functional groups with CN moieties which may be invoked to explain the dual (amphiphilic) reactivity is proven by NEXAFS studies on ultrathin plasma-treated PE films, confirming significant amounts of nitrogen in CN bonds and carbon in CC bonds. KW - X-ray spectroscopy KW - IR spectroscopy KW - Plasma-nitrogenated polyolefin surfaces KW - Unsaturated CN bonds KW - NEXAFS PY - 2017 DO - https://doi.org/10.1002/ppap.201700066 SN - 1612-8869 SN - 1612-8850 VL - 15 IS - 1 SP - e1700066, 1 EP - 15 PB - WILEY-VCH Verlag GmbH & Co. KGaA, CY - Weinheim AN - OPUS4-43786 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Holzweber, Markus A1 - Lippitz, Andreas A1 - Krüger, K. A1 - Jankowski, J. A1 - Unger, Wolfgang T1 - Surface characterization of dialyzer polymer membranes by imaging ToF-SIMS and quantitative XPS line scans N2 - The surfaces of polymeric dialyzer membranes consisting of polysulfone and polyvinylpyrrolidone were investigated regarding the lateral distribution and quantitative surface composition using time-of-flight secondary-ion-mass-spectrometry and x-ray photoelectron spectroscopy. Knowledge of the distribution and composition on the outer surface region is of utmost importance for understanding the biocompatibility of such dialyzer membranes. Both flat membranes and hollow fiber membranes were studied. KW - Tof SIMS KW - XPS KW - Dialyzer membrane KW - Surface analysis KW - Polymer PY - 2015 DO - https://doi.org/10.1116/1.4907937 SN - 1934-8630 SN - 1559-4106 VL - 10 IS - 1 SP - 019011-1 EP - 019011-7 PB - AVS CY - New York, NY, USA AN - OPUS4-32740 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Guo, Y. A1 - Lippitz, Andreas A1 - Saftien, P. A1 - Unger, Wolfgang A1 - Kemnitz, E. T1 - Tuning the surface properties of novel ternary iron(III) fluoride-based catalysts using the template effect of the matrix N2 - Sol–gel prepared ternary FeF3–MgF2 materials have become promising heterogeneous catalysts due to their porosity and surface Lewis/Brønsted acidity (bi-acidity). Despite the good catalytic performance, nanoscopic characterisations of this type of material are still missing and the key factors controlling the surface properties have not yet been identified, impeding both a better understanding and further development of ternary fluoride catalysts. In this study, we characterised the interaction between the bi-acidic component (FeF3) and the matrix (MgF2) on the nano-scale. For the first time, the formation pathway of FeF3–MgF2 was profiled and the template effect of MgF2 during the synthesis process was discovered. Based on these new insights two novel materials, FeF3–CaF2 and FeF3–SrF2, were established, revealing that with decreasing the atomic numbers (from Sr to Mg), the ternary fluorides exhibited increasing surface acidity and surface area but decreasing pore size. These systematic changes gave rise to a panel of catalysts with tuneable surface and bulk properties either by changing the matrix alkaline earth metal fluoride or by adjusting their ratios to Fe or both. The template effect of the alkaline earth metal fluoride matrix was identified as the most probable key factor determining the surface properties and further influencing the catalytic performance in ternary fluoride based catalysts, and paves the way to targeted design of next-generation catalysts with tunable properties. KW - Catalysis KW - Surface analysis KW - XPS PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-327410 DO - https://doi.org/10.1039/c4dt03229b SN - 1477-9226 SN - 1477-9234 SN - 1364-5447 VL - 44 IS - 11 SP - 5076 EP - 5085 PB - RSC CY - Cambridge AN - OPUS4-32741 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Saravanan, S. A1 - Balamurugan, M. A1 - Lippitz, Andreas A1 - Fonda, E. A1 - Swaraj, Sufal T1 - XANES studies of titanium dioxide nanoparticles synthesized by using Peltophorum pterocarpum plant extract N2 - The preparation and characterization of a Titanium dioxide (TiO2) by a simple, cost effective, facile and eco-friendly green synthesis method using Peltophorum pterocarpum plant extract is presented. The green synthesized nanoparticles were characterized using X-ray diffraction (XRD), Raman spectroscopy, High-resolution transmission electron microscopy (HR-TEM) and X-ray absorption near edge spectroscopy (XANES). XRD results show that the prepared TiO2 NPs were significantly crystalline with various percentages of anatase and rutile phases. The nanoparticles were found to have different diameters ranging from 20 to 80 nm. No evidence of any intermediate or different TiO2 phases were found in XANES measurements performed at the Ti K- and L-edge. It is shown that the TiO2 NPs with high uniformity, high surface area and minimum aggregation can be prepared with relative ease and the desired anatase: rutile phase ratio can be obtained by controlling the experimental conditions. KW - XANES KW - Raman KW - XRD KW - NEXAFS KW - Titanium dioxide PY - 2016 UR - http://www.sciencedirect.com/science/article/pii/S0921452616304197 DO - https://doi.org/10.1016/j.physb.2016.09.011 SN - 0921-4526 IS - 503 SP - 86 EP - 92 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-39805 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bernsmeier, D. A1 - Bernicke, M. A1 - Ortel, Erik A1 - Bergmann, A. A1 - Lippitz, Andreas A1 - Nissen, J. A1 - Schmack, R. A1 - Strasser, P. A1 - Polte, J. A1 - Kraehnert, R. T1 - Nafion-free carbon-supported electrocatalysts with superior hydrogen evolution reaction performance by soft templating N2 - Efficient water electrolysis requires electrode coatings with high catalytic activity. Platinum efficiently catalyzes the hydrogen evolution reaction in acidic environments, but is a rare and expensive metal. The activity achieved per metal atom can be increased if small Pt particles are dispersed onto electrically conductive, highly accessible and stable support materials. However, the addition of Nafion, a typical binder material used in the manufacture of electrode coatings, can decrease catalytic activity by the blocking of pores and active surface sites. A new approach is reported for the direct synthesis of highly active Nafion-free Pt/C catalyst films consisting of small Pt nanoparticles supported in size-controlled mesopores of a conductive carbon film. The synthesis relies on the co-deposition of suitable Pt and C precursors in the presence of polymer micelles, which act as pore templates. Subsequent carbonization in an inert atmosphere produces porous catalyst films with controlled film thickness, pore size and particle size. The catalysts clearly outperform all Nafion-based Pt/C catalysts reported in the literature, particularly at high current densities. KW - XPS KW - SEM KW - TEM KW - SAXS KW - Catalysis KW - Electrochemistry PY - 2017 DO - https://doi.org/10.1002/celc.201600444 SN - 2196-0216 VL - 4 IS - 1 SP - 221 EP - 229 PB - Wiley Online Library CY - Weinheim AN - OPUS4-39733 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Graf, Nora A1 - Yegen, E. A1 - Gross, Thomas A1 - Lippitz, Andreas A1 - Weigel, W. A1 - Krakert, S. A1 - Terfort, A. A1 - Unger, Wolfgang T1 - XPS and NEXAFS studies of aliphatic and aromatic amine species on functionalized surfaces N2 - The chemical constitution of functionalized supports is an important parameter that determines their performance in a broad range of applications, e.g. for immobilization of biomolecules. Supports with amino functionalized surfaces are also often used for DNA microarray experiments. However, spectral data which have been reported for surfaces with amino functionalities suffer from some inconsistencies. In this article a detailed XPS (X-ray photoelectron spectroscopy) and NEXAFS (Near edge X-ray absorption fine structure) database for amino functionalized surfaces is presented. Amino-terminated surfaces prepared from aliphatic and aromatic aminosilanes or aminothiols and a field sample are considered. Effects of aging in air and damage by radiation are addressed as well. KW - Near edge X-ray absorption fine structure (NEXAFS) KW - Self-assembled monolayers KW - Amino-functionalized surfaces KW - X-ray photoelectron spectroscopy (XPS) PY - 2009 DO - https://doi.org/10.1016/j.susc.2009.07.029 SN - 0039-6028 VL - 603 IS - 18 SP - 2849 EP - 2860 PB - Elsevier CY - Amsterdam AN - OPUS4-19832 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietrich, Paul A1 - Graf, Nora A1 - Gross, Thomas A1 - Lippitz, Andreas A1 - Krakert, S. A1 - Schüpbach, B. A1 - Terfort, A. A1 - Unger, Wolfgang T1 - Amine species on self-assembled monolayers of omega-aminothiolates on gold as identified by XPS and NEXAFS spectroscopy N2 - Functionalised surfaces are of interest in many fields, e.g. in biomedicine, materials science and molecular electronics. In this study a series of self-assembled aliphatic and aromatic monolayers on gold substrates with terminal amino groups was investigated. Four different thiol molecules were used: aliphatic 11-aminoundecane-1-thiol (AUDT), aromatic 4-aminobenzenethiol (ABT) and aromatic ω-amino thiols with an alkyl spacer as 4-aminophenylbutane-1-thiol (APBT) and 3-(4''-amino-1,1':4',1''-terphenyl-4-yl)propane-1-thiol (ATPT). Evaluation of N 1s XPS data revealed that on the aromatic self-assembled monolayers (SAMs) amino groups exist preferentially as primary amines, whereas on the aliphatic SAM protonated and/or hydrogen-bonded amines are the major species. This result is crosschecked by N K edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy and can be rationalised by the different basicity of aliphatic and aromatic amines. KW - Self-assembled monolayer KW - Amines KW - XPS KW - NEXAFS KW - Surface analysis PY - 2010 DO - https://doi.org/10.1002/sia.3224 SN - 0142-2421 SN - 1096-9918 VL - 42 SP - 1184 EP - 1187 PB - Wiley CY - Chichester AN - OPUS4-21498 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Dietrich, Paul A1 - Graf, Nora A1 - Gross, Thomas A1 - Lippitz, Andreas A1 - Schüpbach, B. A1 - Terfort, A. A1 - Unger, Wolfgang T1 - Characterization of self-assembled monolayers of terphenylthiols with amine head groups KW - Terphenylthiolate SAMs KW - Gold KW - Microarray KW - NEXAFS PY - 2008 SP - 195 EP - 197 AN - OPUS4-22909 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Graf, Nora A1 - Yegen, E. A1 - Lippitz, Andreas A1 - Treu, Dieter A1 - Wirth, Thomas A1 - Unger, Wolfgang T1 - Optimization of cleaning and aminosilanization protocols for Si wafers to be used as platforms for biochip microarrays by surface analysis (XPS, ToF-SIMS and NEXAFS spectroscopy) N2 - It is known that aminosilanized Si wafers may be used as microarray platforms. Results of an XPS study of a cleaning applied to Si wafers prior to aminosilanization are presented and discussed. Furthermore, the results of an aminosilanization protocol optimized in terms of nitrogen chemistry are described. After optimization of the protocol a free amine content of 94% was reached. The surface chemistry was investigated in this study by using XPS, time of flight (ToF)-SIMS and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Reference to aminosilanization protocols reported in the literature has been made. KW - Aminosilanization KW - Si wafers KW - Microarray KW - XPS KW - ToF-SIMS KW - NEXAFS PY - 2008 DO - https://doi.org/10.1002/sia.2621 SN - 0142-2421 SN - 1096-9918 VL - 40 IS - 3-4 SP - 180 EP - 183 PB - Wiley CY - Chichester AN - OPUS4-17192 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yegen, E. A1 - Lippitz, Andreas A1 - Treu, Dieter A1 - Unger, Wolfgang T1 - Derivatization of amino groups by pentafluorobenzaldehyde (PFB) as observed by XPS and NEXAFS spectroscopy on spin coated 4,4'-methylenebis(2,6-diethylaniline) films N2 - A toluene solution of 4,4´-methylenebis(2,6-diethylaniline) was spin coated on Si wafers. The samples were derivatized with pentafluorobenzaldehyde (PFB) in order to determine the primary amino groups on the surface. XPS C 1s and N 1s and C and N K-edge NEXAFS of underivatized and derivatized films were carefully analyzed. The result was that after 10 min of exposure the gas-surface reaction was already completed. A reasonable derivatization reaction yield in the order of 90% is derived from the experiments. This number correlates well to a reaction yield obtained by a wet chemical approach. KW - Amino groups KW - Derivatization KW - PFB KW - XPS KW - NEXAFS PY - 2008 DO - https://doi.org/10.1002/sia.2685 SN - 0142-2421 SN - 1096-9918 VL - 40 IS - 3-4 SP - 176 EP - 179 PB - Wiley CY - Chichester AN - OPUS4-17193 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietrich, Paul A1 - Graf, Nora A1 - Gross, Thomas A1 - Lippitz, Andreas A1 - Schüpbach, B. A1 - Bashir, A. A1 - Wöll, Ch. A1 - Terfort, A. A1 - Unger, Wolfgang T1 - Self-assembled monolayers of aromatic omega-aminothiols on gold: surface chemistry and reactivity N2 - Amino-terminated self-assembled monolayers on gold substrates were studied by X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS) measurements, and atomic force microscopy (AFM). Two different ω-amino-4,4'-terphenyl substituted alkanethiols of the general structure H2N-(C6H4)3-(CH2)n-SH (ATPn) were used: 2-(4''-amino-1,1':4',1''-terphenyl-4-yl)ethane-1-thiol (n = 2, ATP2) and 3-(4''-amino-1,1':4',1''-terphenyl-4-yl)propane-1-thiol (n = 3, ATP3). Moreover, the addressability of amino groups within the films was investigated by chemical derivatization of ATPn SAMs with 3,5-bis(trifluoromethyl)phenyl isothiocyanate (ITC) forming fluorinated thiourea ATPn-F films. Evaluation of high-resolution C 1s and N 1s XPS data revealed successful derivatization of at least 50% of surface amino species. Furthermore, it could be demonstrated by angle-resolved NEXAFS spectroscopy that chemical derivatization with ITC has no noticeable influence on the preferential upright orientation of the molecules in the SAMs. KW - Gold KW - Self-assembled monolayer KW - Thiols KW - Amino surfaces KW - XPS KW - NEXAFS PY - 2010 DO - https://doi.org/10.1021/la903293b SN - 0743-7463 SN - 1520-5827 VL - 26 IS - 6 SP - 3949 EP - 3954 PB - American Chemical Society CY - Washington, DC AN - OPUS4-20990 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietrich, Paul A1 - Horlacher, T. A1 - Girard-Lauriault, Pierre-Luc A1 - Gross, Thomas A1 - Lippitz, Andreas A1 - Min, Hyegeun A1 - Wirth, Thomas A1 - Castelli, R. A1 - Seeberger, P. H. A1 - Unger, Wolfgang T1 - Adlayers of dimannoside thiols on gold: surface chemical analysis N2 - Carbohydrate films on gold based on dimannoside thiols (DMT) were prepared, and a complementary surface chemical analysis was performed in detail by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), near-edge X-ray absorption fine structure (NEXAFS), FT-IR, and contact angle measurements in order to verify formation of ω-carbohydrate-functionalized alkylthiol films. XPS (C 1s, O 1s, and S 2p) reveals information on carbohydrate specific alkoxy (C–O) and acetal moieties (O–C–O) as well as thiolate species attached to gold. Angle-resolved synchrotron XPS was used for chemical speciation at ultimate surface sensitivity. Angle-resolved XPS analysis suggests the presence of an excess top layer composed of unbound sulfur components combined with alkyl moieties. Further support for DMT attachment on Au is given by ToF-SIMS and FT-IR analysis. Carbon and oxygen K-edge NEXAFS spectra were interpreted by applying the building block model supported by comparison to data of 1-undecanethiol, poly(vinyl alcohol), and polyoxymethylene. No linear dichroism effect was observed in the angle-resolved C K-edge NEXAFS. KW - Carbohydrates KW - Self-assembled monolayer KW - XPS KW - NEXAFS KW - ToF-SIMS KW - Surface chemical analysis PY - 2011 DO - https://doi.org/10.1021/la104038q SN - 0743-7463 SN - 1520-5827 VL - 27 IS - 8 SP - 4808 EP - 4815 PB - American Chemical Society CY - Washington, DC AN - OPUS4-23554 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Manier, Charles-Alix A1 - Spaltmann, Dirk A1 - Woydt, Mathias A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - NEXAFS study of carbon hard coatings tribo-tested under slip-rolling conditions KW - Synchrotron KW - NEXAFS KW - Carbon hard coating KW - Tribology PY - 2007 UR - http://www.helmholtz-berlin.de/media/media/oea/web/pr_webseite/druckschriften/berichte/bessy/annual_report_2006.pdf#page=159 SN - 0179-4159 SP - 159 EP - 161 PB - Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung CY - Berlin AN - OPUS4-17452 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Girard-Lauriault, P.-L. A1 - Wertheimer, M. R. A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - NEXAFS Surface Chemical Characterisation of Atmospheric Pressure deposited N-rich Plasma-Polymer Films for Tissue Engineering KW - Synchrotron KW - NEXAFS KW - Plasma-Polymer KW - Tissue Engineering PY - 2007 UR - http://www.helmholtz-berlin.de/media/media/oea/web/pr_webseite/druckschriften/berichte/bessy/annual_report_2006.pdf#page=248 SN - 0179-4159 SP - 248 EP - 250 PB - Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung CY - Berlin AN - OPUS4-17453 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Girard-Lauriault, P.-L. A1 - Desjardins, P. A1 - Unger, Wolfgang A1 - Lippitz, Andreas A1 - Wertheimer, M. R. T1 - Chemical characterisation of nitrogen-rich plasma-polymer films deposited in dielectric barrier discharges at atmospheric pressure N2 - We have used an atmospheric pressure DBD apparatus to deposit novel families of N-rich plasma polymers (PP:N), using mixtures of three different hydrocarbon precursors in nitrogen at varying respective gas flow ratios. This research focuses on the overall chemical characterisation of those materials, with specific attention to (semi)-quantitative analysis of functional groups. Well-established and some lesser-known analytical techniques have been combined to provide the best possible chemical and structural characterisations of these three families of PP:N thin films, namely XPS, NEXAFS and FT-IR spectroscopy. KW - NEXAFS KW - XPS KW - DBD-plasma KW - Plasma polymerization PY - 2008 DO - https://doi.org/10.1002/ppap.200800054 SN - 1612-8850 SN - 1612-8869 VL - 5 IS - 7 SP - 631 EP - 644 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-17820 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Truica-Marasescu, F. A1 - Girard-Lauriault, P.-L. A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Wertheimer, M. R. T1 - Nitrogen-rich plasma polymers: Comparison of films deposited in atmospheric- and low-pressure plasmas N2 - Low- and atmospheric-pressure plasma co-polymerisations of binary gas mixtures of C2H4 and NH3 or N2, respectively, were investigated for depositing N-rich plasma polymer coatings for biomedical applications. Deposition kinetics and relevant surface characteristics of resulting plasma polymerised ethylene enriched with nitrogen, “PPE:N”, coatings were investigated as a function of the gas mixture ratio, X = NH3(N2)/C2H4. Physico-chemical properties of the coatings were determined using a combination of complementary surface-sensitive techniques: for example, total nitrogen concentrations, [N], up to 40 at.% were measured by X-ray Photoelectron Spectroscopy, XPS, while those of primary amines, [–NH2], were determined by performing chemical derivatisation followed by XPS analyses. PPE:N films were further characterised by UV–VIS Ellipsometry, Near Edge X-ray Absorption Fine Structure Spectroscopy, IR Spectroscopy and by Contact Angle Goniometry measurements. The stability of the coatings was tested, both in terms of water solubility and of “ageing” in ambient atmosphere. For the latter, selected samples were stored in the laboratory for different durations, in order to assess possible changes in their chemical structures. KW - Aging KW - Deposition process KW - Ethylene KW - Fourier transform infrared spectroscopy (FTIR) KW - Glow discharge KW - Plasma polymers KW - Surface chemistry KW - Surface energy PY - 2008 DO - https://doi.org/10.1016/j.tsf.2008.02.033 SN - 0040-6090 VL - 516 IS - 21 SP - 7406 EP - 7417 PB - Elsevier CY - Amsterdam AN - OPUS4-18279 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Graf, Nora A1 - Lippitz, Andreas A1 - Gross, Thomas A1 - Pippig, F. A1 - Holländer, A. A1 - Unger, Wolfgang T1 - Determination of accessible amino groups on surfaces by chemical derivatization with 3,5-bis(trifluoromethyl)phenyl isothiocyanate and XPS/NEXAFS analysis N2 - The determination of amino groups on surfaces capable of binding biomolecules is important for the understanding and optimization of technologically relevant coupling processes. In this study, three different types of amino-functionalized model surfaces, amino thiolate on Au, amino siloxane on Si, and polyethylene (PE) foils and films reacted with 1,2-diaminoethane (DAE) were derivatized with 3,5-bis(trifluoromethyl)phenyl isothiocyanate. Subsequently, these samples were analyzed by chemical derivatization X-ray photoelectron spectroscopy (CD-XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). The determination of amino groups by this analytical approach allows gaining insight into the availability of groups on surfaces that can actually serve as attachment sites for biomolecules in technical applications. In the case of the amino thiolate on Au, almost 90% of the expected amino groups were detected by CD-XPS. Investigation of the amino siloxane films revealed lower yields for the derivatization reaction in the order of 30%. The lowered reaction yields are thought to be due to interactions between the amino siloxane`s amino and silanol groups or the underlying substrate, making them inaccessible to the derivatization agent. The aminated PE samples are characterized by a complex surface chemistry and structure, and reaction yields of the derivatization reaction cannot be unequivocally derived. However, 1-3% of the total carbon atoms in the surface layer were found to be bound to amino groups accessible to the derivatization agent. It can be concluded that, depending on the detailed character of the investigated amino-terminated surface, the amount of amino groups accessible to CD-XPS can be substantially lower than the total amount of amino groups present at the surface. KW - XPS/ESCA KW - NEXAFS/XANES KW - CD-XPS KW - Amino-functionalized surfaces KW - SAM PY - 2010 DO - https://doi.org/10.1007/s00216-009-3233-7 SN - 1618-2642 SN - 1618-2650 VL - 396 IS - 2 SP - 725 EP - 738 PB - Springer CY - Berlin AN - OPUS4-20744 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Unger, Wolfgang A1 - Lippitz, Andreas A1 - Koprinarov, Ivaylo A1 - Ghode, Archana A1 - Geng, Sh. A1 - Kühn, Gerhard T1 - Plasma-based introduction of monosort functional groups of different type and density onto polymer surfaces. Part 1: Behaviour of polymers exposed to oxygen plasma N2 - Several approaches were investigated to produce monosort functionalized polymer surfaces with a high density and homogeneity of functional groups: (i) Plasma oxidation followed by wet-chemical reduction, (ii) formation of radicals and grafting on of functional group carrying molecules, (iii) plasma bromination followed by (iv) Williamson or Gabriel-like synthesis of spacer molecules, and (v) a pulsed plasma polymerization of functional groups bearing monomers or (vi) their copolymerisation with other comonomers. The formation of hydroxyl (OH), primary amino (NH2), and carboxyl (COOH) groups was studied in detail. The oxygen plasma treatment (i) in a low-pressure non-isothermal glow discharge results in the formation of a wide variety of O functional groups, polymer degradation and crosslinking. Low power densities and short exposure times (0.1 to 2 s) are required to functionalize a surface while preserving the original polymer structure. Carbonate, ester, and aromatic groups are rapidly degraded by an oxygen plasma treatment leading to scissions of polymer backbones and loss in molecular weight. Also the formation of macrocycles and C=C bonds was observed in a region of around 4 nm in depth. The investigated polymers could be classified by their degradation behaviour on exposure to the oxygen plasma.___TAGSTART___BR___TAGEND___ In order to maximize the process selectivity for OH groups, the variety of oxygen functionalities formed by the oxygen plasma was wet-chemically reduced by diborane, vitridetrade (Na complex), and LiAlH4. Typical yields were 9 to 14 OH groups per 100 carbon atoms.___TAGSTART___BR___TAGEND___ Plasma bromination (iii) (40 Br per 100 C atoms) of polymers, followed by grafting of spacer molecules (iv), has been proved to be a highly selective reaction.___TAGSTART___BR___TAGEND___ Another way to produce high densities of monosort functionalities was the pulsed plasma polymerization of functional group bearing monomers such as allylamine, allylalcohol or acrylic acid (v). The retention of chemical structure and functional groups during plasma polymerization was achieved by using low power densities and the pulsed plasma technique. The maximum yields were 30 OH, 18 NH2, and 24 COOH groups per 100 C atoms. To vary the density of functional groups a chemical copolymerization with ''chain-extending'' comonomers such as butadiene and ethylene was initiated in the pulsed plasma (vi). Additionally, the often-observed post-plasma oxidations of such layers initiated by reaction of trapped radicals with oxygen from the air were successfully suppressed by using NO gas as radical quencher. PY - 2003 DO - https://doi.org/10.1163/156855403765826865 VL - 10 IS - 2-3 SP - 139 EP - 171 PB - North-Holland CY - New York, NY AN - OPUS4-2705 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ünveren, Ercan A1 - Kemnitz, E. A1 - Hutton, S. A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Analysis of highly resolved x-ray photoelectron Cr 2p spectra obtained with a Cr2O3 powder sample prepared with adhesive tape KW - High-resolution XPS KW - Cr2O3 powder KW - Multiplet splitting PY - 2004 SN - 0142-2421 SN - 1096-9918 VL - 36 SP - 92 EP - 95 PB - Wiley CY - Chichester AN - OPUS4-3427 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Swaraj, Sufal A1 - Oran, Umut A1 - Lippitz, Andreas A1 - Schulze, Rolf-Dieter A1 - Friedrich, Jörg Florian A1 - Unger, Wolfgang T1 - Surface Analysis of Plasma-Deposited Polymer Films, 2: Analysis of Post-Plasma Air Reacted Plasma Polymerized Styrene by X-Ray Photoelectron Spectroscopy and X-Ray Absorption Spectroscopy N2 - Chemical properties of plasma-polymerized styrene films can be effectively controlled by the appropriate choice of external plasma parameters, such as duty cycle, power and monomer pressure. Chemical properties here are the regularity of the primary structure, the amount of long living radicals and branching or cross-linking or both in plasma polymerized styrene films, which can be indirectly monitored by X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Principally, XPS and NEXAFS spectra of plasma-polymerized styrene show all the spectroscopic fingerprints characteristic of atactic polystyrene indicating an inherent similarity of the respective primary chemical structures. There is an increase in irregularity and radical concentration for the plasma deposited films with increasing duty cycle or power. With an increase in monomer pressure, a decreased level of monomer fragmentation and, consequently, an increase in regularity must be concluded from the experimental data. The applied power regulates the fragmentation of the monomers as monitored by spectroscopic signals correlated to the aromatic rings. A trend in the extent of the post-plasma oxygen incorporation according to the variation of the various external plasma parameters was deduced, which agrees with earlier ToF-SIMS findings KW - Chemical characterization KW - ESCA/XPS KW - NEXAFS KW - Plasma polymerization KW - Polystyrene PY - 2004 DO - https://doi.org/10.1002/ppap.200400022 SN - 1612-8850 SN - 1612-8869 VL - 1 SP - 134 EP - 140 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-6935 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Retzko, Iris A1 - Friedrich, Jörg Florian A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Chemical analysis of plasma-polymerized films: The application of X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (NEXAFS) and fourier transform infrared spectroscopy (FTIR) N2 - Selected FTIR, XPS and NEXAFS spectroscopy results obtained with films deposited with different plasma polymerization processes and different monomers (styrene, acetylene, ethylene and butadiene) are presented. In detail FTIR spectra, XPS surveys, XPS valence bands and core level signals including shake-up features as well as carbon K-edge absorption spectra are qualitatively and, in some cases, semi-quantitatively considered. Information on the film formation, the chemistry of the films and the film stability against air exposure are derived from spectroscopic features. With styrene chemically rather well defined plasma polymer layers can be formed with rather high deposition rates applying a pulse plasma process. Using ethylene, acetylene or butadiene as a monomer in the plasma deposition process the deposition rates are smaller. Using these monomers plasma polymer films can be obtained with a primary chemical structure which is similar to each other but more or less different from those of the respective conventional polymers. The main difference between these samples is their individual concentration of unsaturated carbon species. Finally, a technologically relevant example, i.e. a plasma deposited polymer barrier layer deposited on the inner wall of a poly(ethylene) vessel is briefly considered. KW - Plasma polymer KW - Styrene KW - Ethylene KW - Acethylene KW - Butadiene KW - XPS KW - NEXAFS KW - FTIR KW - Chemical characterization KW - Deposition process KW - Stability PY - 2001 DO - https://doi.org/10.1016/S0368-2048(01)00330-9 SN - 0368-2048 SN - 1873-2526 VL - 121 IS - 2 SP - 111 EP - 129 PB - Elsevier CY - Amsterdam AN - OPUS4-6938 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Wolfgang A1 - Gross, Thomas A1 - Böse, Olaf A1 - Lippitz, Andreas A1 - Fritz, Thomas A1 - Gelius, U. T1 - VAMAS TWA2 Project A2: evaluation of static charge stabilization and determination methods in XPS on non-conducting samples. Report on an inter-laboratory comparison N2 - First results of an inter-laboratory comparison (27 participants in Europe, Japan and USA) of XPS data obtained with non-conducting samples are presented. Binding energies of Al 2s for alumina, N 1s and imide C 1s for Kapton and Sr 3p3/2 for a strontium titanate film on glass were obtained after static charge referencing with the help of 15 nm gold particles deposited at the surface of the test samples. For the alumina sample C 1s static charge referenced data are also presented. Repeat standard deviations (sr), between standard deviations (sb), reproducibility standard deviations (sR) and total means are evaluated from the experimental data. It can be stated that although the repeat standard deviation is as small as 0.05 eV in the best case, the standard deviation characterizing the reproducibility of the method is obviously not better than 0.15 eV in the best case at the present time. The knowledge of these standard deviations is important for metrology, validations of analytical procedures relying on qualitative photoelectron spectroscopy and XPS databanking. KW - XPS KW - ESCA KW - Binding energy KW - Inter-laboratory comparison PY - 2000 DO - https://doi.org/10.1002/1096-9918(200008)29:8<535::AID-SIA900>3.0.CO;2-5 SN - 0142-2421 SN - 1096-9918 VL - 29 SP - 535 EP - 543 PB - Wiley CY - Chichester AN - OPUS4-6939 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kühn, Gerhard A1 - Retzko, Iris A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Friedrich, Jörg Florian T1 - Homofunctionalized polymer surfaces formed by selective plasma processes N2 - Several possibilities exist to produce a modified polymer surface with a high density of only one sort of functional group such as: (i) the plasma grafting of unfragmented monomer molecules and their polymerization forms OH, NH2, COOH groups, etc. in concentrations of approximately 25 groups per 100 C atoms; (ii) selective plasma bromination provides 10–25 CBr groups; (iii) the plasma oxidation of polymer surfaces in an O2 plasma followed by the chemical reduction of all O-containing groups to OH groups by diborane, vitride™ (Na complex) or LiAlH4 yields 9–14 OH groups per 100 carbon atoms; and (iv) the grafting of spacers with different endgroups onto OH or CBr groups produces 7–10 spacer molecules/100 C. This work was focused on the formation of thin plasma deposited polymer layers with a maximum of (homo)functional groups and with a minimum of chemical irregularities using the pulsed plasma technique. The monomers were allylalcohol, allylamine, acrylonitrile and acrylic acid. The further intent was to study the interactions of functional groups (OH, COOH, NH2) and deposited metals (Cr, Al, Ti). It was expected that more basic (NH2), weakly basic or neutral (OH) or more acidic (COOH) groups would show different interactions and chemical reactions with metal atoms. KW - Pulsed plasma polymerization KW - Functional groups KW - Long-term stability KW - Polymer-metal composites PY - 2001 DO - https://doi.org/10.1016/S0257-8972(01)01056-8 SN - 0257-8972 VL - 142-144 SP - 494 EP - 500 PB - Elsevier Science CY - Lausanne AN - OPUS4-6971 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Retzko, Iris A1 - Kühn, Gerhard A1 - Unger, Wolfgang A1 - Lippitz, Andreas T1 - Plasma polymers with chemically defined structures in contact with metals N2 - The retention of chemical structure and functional groups during plasma polymerization was investigated. Usually plasma polymer layers, prepared by a continuous wave radio-frequency plasma, are often chemically irregular in their structure and composition. To minimize these irregularities low wattages and the pulsed plasma technique were applied to avoid fragmentations. The first goal was to produce plasma polymers comprising double or triple bonds as precursors for electrically conducting polymers. Acetylene, ethylene, butadiene and polystyrene were used as monomers and deposited as thin polymer films by pulsed plasmas of low wattages. Styrene polymerization was strongly enhanced in the dark phase (plasma off) of a pulsed r.f. plasma caused by the reactivity of the vinyl-type double bond. This could be confirmed by a verification of a rather high chemical regularity of the film sample. The oxygen content of this film measured by X-ray photoelectron spectrometry (XPS) was in situ 0% and after 24 h exposure to air lower than 1%. Additionally, post-plasma oxidations of trapped radicals with air could be suppressed using NO gas as radical quencher. Such quenched plasma polymer layers were completely stable against oxidation for a number of weeks. During the low-wattage pulse plasma polymerization metal atoms were simultaneously or layer by layer evaporated into the growing layer and in situ measured by XPS. These metal atoms are acting as dopants. Here, Li, K, Mg and Cr were used at different concentrations providing electrical conductivity and magnetic properties for the film. KW - Pulsed plasma KW - Plasma polymerization KW - Doping with metal atoms KW - Encapsulation of nanoparticles PY - 2001 DO - https://doi.org/10.1016/S0257-8972(01)01051-9 SN - 0257-8972 VL - 142-144 SP - 460 EP - 467 PB - Elsevier Science CY - Lausanne AN - OPUS4-6972 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Retzko, Iris A1 - Friedrich, Jörg Florian A1 - Kühn, Gerhard A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Eine neue Generation von alterungsbeständigen Plasmapolymeren mit definierter chemischer Struktur T2 - 8. Neues Dresdner Vakuumtechnisches Kolloquium (NDVaK) CY - Dresden, Deutschland DA - 2000-10-19 PY - 2000 VL - 8 SP - 110 EP - 114 CY - Dresden AN - OPUS4-6974 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Wolfgang A1 - Lippitz, Andreas A1 - Koprinarov, Ivaylo A1 - Friedrich, Jörg Florian A1 - Wöll, Ch. T1 - K-Edge Soft X-ray Absorption (NEXAFS) Spectroscopy In Surface Chemical Analysis of Polymers T2 - International Discussion Meeting Advanced Methods of Polymer Characterization: New Developments and Applications in Industry CY - Mainz, Germany DA - 1999-03-15 PY - 1999 SP - P3.53 CY - Mainz AN - OPUS4-6925 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Retzko, Iris A1 - Treu, Dieter A1 - Matsubayashi, N. A1 - Imamura, M. A1 - Tanaka, T. A1 - Schulz, H. A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Analysis of carbon materials and plasma polymers by X-ray photoelectron spectroscopy and X-ray absorption spectroscopy (XPS, XAS) T2 - AIST-BAM Symposium on Materials Surface Technology in Twin Institute Programme CY - Tsukuba, Japan DA - 2003-02-18 PY - 2003 SP - 59 EP - 65 AN - OPUS4-6928 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Güttler, B. A1 - Schiel, D. A1 - Danzebrink, H. A1 - Unger, Wolfgang A1 - Gross, Thomas A1 - Lippitz, Andreas A1 - Müller, J.-P. T1 - Physical and Chemical Characterization of Thermal and Native Siliconoxide layers on Silicon T2 - Symposium "Reference Materials for Technologies in the New Millenium" CY - Berlin, BAM, Germany DA - 2000-05-22 PY - 2000 SP - 1(?) EP - 7(?) AN - OPUS4-6924 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Unger, Wolfgang A1 - Lippitz, Andreas A1 - Friedrich, Jörg Florian A1 - Koprinarov, Ivaylo A1 - Weiss, K. A1 - Wöll, Ch. ED - Mittal, K. T1 - The Application of Near Edge X-ray Absorption Fine Structures (NEXAFS) Spectroscopy and X-ray Photoelectron Spectroscopy (XPS) in Surface Analysis of Chromium-evaporated Polymers and Organic Films PY - 1998 SN - 90-6764-290-8 SP - 147 EP - 168 PB - VSP CY - Utrecht AN - OPUS4-6986 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Koprinarov, Ivaylo A1 - Lippitz, Andreas A1 - Friedrich, Jörg Florian A1 - Unger, Wolfgang A1 - Wöll, Ch. T1 - Oxygen plama induced degradation of the surface of poly(styrene), poly(bisphenol-A-carbonate) and poly(ethylene terephthalate) as observed by soft X-ray absorption spectroscopy (NEXAFS) KW - Oxygen DC plasma treatment KW - Plasma degradation KW - X-ray absorption spectroscopy (NEXAFS) PY - 1998 SN - 0032-3861 SN - 1873-2291 VL - 39 IS - 14 SP - 3001 EP - 3009 PB - Springer CY - Berlin AN - OPUS4-6990 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Friedrich, Jörg Florian A1 - Koprinarov, Ivaylo A1 - Giebler, Rainer A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Reactions and Intermediates at the Metal-Polymer Interface - Detected by XPS and NEXAFS Spectroscopy T2 - 4th European Conference on Adhesion (EURADH '98) ; 1st World Congress on Adhesion and Related Phenomena (WCARP) CY - Garmisch-Partenkirchen, Germany DA - 1998-09-06 PY - 1998 SN - 0021-8464 VL - 75 IS - 1 SP - 1.60 EP - 1.62 PB - Gordon & Breach CY - New York, NY AN - OPUS4-6991 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Koprinarov, Ivaylo A1 - Lippitz, Andreas A1 - Friedrich, Jörg Florian A1 - Unger, Wolfgang A1 - Wöll, Ch. T1 - Surface analysis of DC oxygen plasma treated or chromium evaporated poly(ethylene terephthalate) foils by soft X-ray absorption spectroscopy (NEXAFS) KW - Biaxially streched poly(ehtylene terephthalate) KW - Oxygen DC plasma treatment KW - Metallization with chromium PY - 1997 SN - 0032-3861 SN - 1873-2291 VL - 38 IS - 8 SP - 2005 EP - 2010 PB - Springer CY - Berlin AN - OPUS4-6998 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Wigant, L. A1 - Unger, Wolfgang A1 - Lippitz, Andreas A1 - Wittrich, H. T1 - Corona, spark and combined UV and ozone modification of polymer films WeBP23 N2 - Different types of plasma, irradiative and chemical activation were compared in terms of surface functionalization. Corona and spark jet plasmas are characterized by low gas temperatures and high rates in surface modification. UV irradiation in the presence of ozone does not involve any particle bombardment and acts only by enhanced photooxidative processes. Although ion implantation can be avoided, this method is not free of radiative damage in both the surface-near region and the bulk of polymers. Furthermore, its functionalization rate is low. In relation to low-pressure O2 plasma modification, all treatments mentioned here have a low efficiency in adhesion promotion due to oxidative degradation of macromolecules and formation of molecular debris known as the ''weak boundary layer''. PY - 1998 DO - https://doi.org/10.1016/S0257-8972(97)00318-6 SN - 0257-8972 VL - 98 IS - 1 SP - 879 EP - 885 PB - Elsevier Science CY - Lausanne AN - OPUS4-7000 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Wigant, L. A1 - Unger, Wolfgang A1 - Lippitz, Andreas A1 - Erdmann, J. A1 - Gorsler, H.-V. T1 - Oberflächenvorbehandlung von Polypropylen in elektrischen Entladungen PY - 1995 SN - 0590-8450 VL - 1 SP - 123 EP - 127 PB - Verl. Coating Thomas CY - St. Gallen AN - OPUS4-7005 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Friedrich, Jörg Florian A1 - Wigant, L. A1 - Unger, Wolfgang A1 - Lippitz, Andreas A1 - Wittrich, H. A1 - Prescher, D. ED - Mittal, K. L. T1 - Barrier properties of plasma-modified polypropylene and polyethyleneterephthalate T2 - International Symposium on Polymer Surface Modification: Relevance to Adhesion CY - Las Vegas, NV, USA DA - 1993-11-03 KW - Plasma fluorination of polymers KW - Deposition of fluorine-containing plasma polymers KW - Barrier formation against solvent permeation KW - Permeation mechanism of solvent mixtures PY - 1996 SN - 90-6764-201-0 VL - 1 SP - 121 EP - 136 PB - VSP CY - Utrecht AN - OPUS4-7006 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Friedrich, Jörg Florian A1 - Unger, Wolfgang A1 - Lippitz, Andreas A1 - Gross, Thomas A1 - Rohrer, P. A1 - Saur, W. A1 - Erdmann, J. A1 - Gorsler, H.-V. ED - Mittal, K. L. T1 - The improvement in adhesion of polyurethane-polypropylene composites by short-time exposure of polypropylene to low and atmospheric pressure plasmas KW - Polyurethane-polypropylene adhesion KW - Low pressure plasma pretreatment KW - Atmospheric pressure plasma treatment KW - Short-time exposure KW - Relevance of functional groups to adhesion KW - Molecular orientation at polymer surfaces PY - 1996 SN - 90-6764-201-0 SP - 49 EP - 72 PB - VSP CY - Utrecht AN - OPUS4-7007 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Wolfgang A1 - Lippitz, Andreas A1 - Friedrich, Jörg Florian T1 - Plasmabehandelte Polymere charakterisieren PY - 1995 SN - 0025-5300 VL - 37 IS - 6 SP - 233 EP - 237 PB - Carl Hanser Verlag CY - München AN - OPUS4-7009 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Unger, Wolfgang A1 - Lippitz, Andreas A1 - Gross, Thomas A1 - Rohrer, P. A1 - Saur, W. A1 - Erdmann, J. A1 - Gorsler, H.-V. T1 - The improvement in adhesion of polyurethane-polypropylene composites by short-time exposure of polypropylene to low and atmospheric pressure plasmas KW - Polyurethane-polypropylene adhesion KW - Low pressure plasma pretreatment KW - Atmospheric pressure plasma treatment KW - Short-time exposure KW - Relevance of functional groups to adhesion KW - Molecular orientation at polymer surfaces PY - 1995 SN - 0169-4243 SN - 1568-5616 VL - 9 IS - 5 SP - 575 EP - 598 PB - VNU Science Press CY - Utrecht AN - OPUS4-7010 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Wigant, L. A1 - Unger, Wolfgang A1 - Lippitz, Andreas A1 - Geng, Sh. A1 - Erdmann, J. A1 - Gorsler, H.-V. T1 - Neue Erkenntnisse zur Plasmamodifizierung von Polymeroberflächen PY - 1995 SN - 0949-8214 VL - 1 SP - 36 EP - 42 PB - Technische Fachhochschule CY - Wildau AN - OPUS4-7011 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Unger, Wolfgang A1 - Lippitz, Andreas T1 - Plasma Modification of Polymer Surfaces PY - 1995 SN - 1022-1360 SN - 0258-0322 SN - 1521-3900 VL - 100 SP - 111 EP - 115 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-7012 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Wigant, L. A1 - Unger, Wolfgang A1 - Lippitz, Andreas A1 - Wittrich, H. A1 - Prescher, D. A1 - Erdmann, J. A1 - Gorsler, H.-V. A1 - Nick, L. T1 - Barrier properties of plasma-modified polypropylene and polyethyleneterephthalate KW - Plasma fluorination of polymers KW - Deposition of fluorine-containing plasma polymers KW - Barrier formation against solvent permeation KW - Permeation mechanism of solvent mixtures PY - 1995 SN - 0169-4243 SN - 1568-5616 VL - 9 IS - 9 SP - 1165 EP - 1180 PB - VNU Science Press CY - Utrecht AN - OPUS4-7013 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Koprinarov, Ivaylo A1 - Friedrich, Jörg Florian A1 - Lippitz, Andreas A1 - Unger, Wolfgang ED - Olefjord, I. ED - Nyborg, L. ED - Briggs, D. T1 - X-ray Absorption Spectroscopy (NEXAFS) of PET Surfaces T2 - 7th European Conference on Applications of Surface and Interface Analysis CY - Göteborg, Sweden DA - 1997-06-16 PY - 1997 SN - 0-471-97827-2 SP - 755 EP - 759 PB - Wiley CY - Chichester AN - OPUS4-7288 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Moritz, W. A1 - Krause, S. A1 - Roth, U. A1 - Klimm, D. A1 - Lippitz, Andreas T1 - Re-activation of an all solid state oxygen sensor N2 - The silicon based semiconductor structure Si/SiO2/Si3N4/LaF3/Pt can be used as a potentiometric oxygen sensor working at room temperature. A thermal re-activation can be applied to overcome the earlier disadvantage of an increase in response time with continuous use. Using the Pt gate electrode as a resistive heater, very short electrical high-power pulses can be applied. A heating time as short as 300 ns was sufficient for the re-activation of the sensor. This way, only the sensitive thin layer system LaF3/Pt was heated, and the whole sensor was at room temperature immediately after heating. Impedance spectroscopy, X-ray photoelectron spectroscopy (XPS) and quadruple mass spectrometric (QMS)–thermogravimetry (TG) were used to investigate the mechanism of deterioration in dynamic sensor behaviour and re-activation. The formation of hydrated carbonate and the desorption of CO2 and H2O have been shown to be the causes. KW - Chemical sensor KW - Thermal treatment KW - Activation KW - LaF3 KW - Pt PY - 2001 DO - https://doi.org/10.1016/S0003-2670(01)00993-X SN - 0003-2670 SN - 1873-4324 SN - 0378-4304 VL - 437 SP - 183 EP - 190 PB - Elsevier CY - Amsterdam AN - OPUS4-6836 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Wolfgang A1 - Gross, Thomas A1 - Lippitz, Andreas T1 - Prüfartenakkreditierung am Beispiel der ESCA N2 - Die Akkreditierung für Prüfverfahren in der Oberflächenanalytik wird gemeinhin als sehr schwierig angesehen. Durch das unlängst eingeführte flexible Konzept der Akkreditierung, auch Prüfartenakkreditierung genannt, eröffnen sich nunmehr neue Möglichkeiten. Aus dem Bereich des Normenwesens in der Oberflächenanalytik erhalten die Prüflaboratorien zusätzliche Unterstützung. Die Validierung von ESCA-Prüfverfahren und ein wohldokumentiertes Prüfmittelmanagement sind weitere Bausteine auf dem Weg zur erfolgreichen Akkreditierung. Oberflächenanalyseverfahren sind akkreditierfähig. PY - 1999 SN - 0344-1733 SN - 1610-8256 SP - 90 EP - 93 PB - Vogel CY - Würzburg AN - OPUS4-6842 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Swaraj, Sufal A1 - Oran, Umut A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - NEXAFS - spectroscopy on plasma-polymerised films prepared from organic molecules (Acrylic acid, allylamine, ethylene) KW - NEXAFS KW - Plasmapolymere KW - Synchrotronstrahlung PY - 2005 UR - http://www.helmholtz-berlin.de/media/media/oea/web/pr_webseite/druckschriften/berichte/bessy/annualreport2004.pdf#page=315 SN - 0179-4159 SP - 315 EP - 317 PB - Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung CY - Berlin AN - OPUS4-7387 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ünveren, Ercan A1 - Kemnitz, E. A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Surface Characterization of Chromia for Chlorine/Fluorine Exchange Reactions N2 - The dismutation of CCl2F2 was used to probe the effect of halogenation of chromia by Cl/F exchange reactions to find out the difference between the halogenated inactive and active catalysts. The heterogeneous reactions were performed in a continuous flow Ni reactor and also under simulated reaction conditions in a reactor where after the reaction X-ray photoelectron spectroscopy (XPS) and X-ray excited Auger electron spectroscopy (XAES) analyses are possible without air exposure of the catalyst, i.e., under so-called "in situ" conditions. The Cr(III) 2p XP spectra, which revealed multiplet splitting features and satellite emission, were used for chemical analysis by using a simple evaluation procedure which neglects this inherent complexity. Chemical analysis was also applied by using chemical state plots for Cr 3s in order to cross-check Cr 2p related results. Both ex and in situ XPS show that as soon as Cr2O3 is exposed to CCl2F2 at 390°C fluorination as well as chlorination takes place at the catalyst surface. When the XPS surface composition reaches approximately 4 at. % fluorination and 6 at. % chlorination, maximum catalytic activity was obtained. Application of longer reaction times did not change significantly the obtained surface composition of the activated chromia. The fluorination and chlorination of chromia was further investigated by various HF and HCl treatments. The activated chromia samples and the Cr2O3, Cr(OH)3, CrF2OH, CrF3·H2O, α-CrF3, β-CrF3, and CrCl3 reference samples with well-known chemical structures were also characterized by X-ray absorption near edge structure (XANES), time-of-flight secondary ion mass spectroscopy (TOF-SIMS), pyridine-FTIR, wet chemical (F and Cl) analysis, X-ray powder diffraction (XRD), and surface area (BET) analysis. The results suggest that the formation of chromium oxide chloride fluoride species, e.g., chromium oxide halides, at the surface is sufficient to provide catalytic activity. The presence of any CrF3 and/or CrCl3 phases on the activated chromia samples was not found. PY - 2005 DO - https://doi.org/10.1021/jp045902r SN - 1520-6106 SN - 1520-5207 SN - 1089-5647 VL - 109 IS - 5 SP - 1903 EP - 1913 PB - Soc. CY - Washington, DC AN - OPUS4-10531 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lippitz, Andreas A1 - Hübert, Thomas T1 - XPS investigations of chromium nitride thin films N2 - Cr–N film coatings were prepared by magnetron sputter deposition at different nitrogen partial pressures. The film characterisation by XRD and DTG gives average bulk compositions of Cr2N and CrN for the coatings. Highly sensitive XPS investigations were performed and the chemical and phase compositions of a film surface range of about 10 nm thickness was estimated quantitatively from the deconvoluted peak intensities. It is demonstrated that the composition of the surface of chromium nitride thin films differs from the core and is more complex in constitution. Not only chromium nitrides (Cr2N and CrN) but also chromium oxynitrides and chromium oxides (CrOx and CrOxHy) were detected. Metallic chromium was also found in films prepared at higher nitrogen flow. The concentration of the estimated phases shows dependence on film preparation and additional heat treatment. KW - XPS KW - ESCA KW - Physical vapour deposition (PVD) KW - CrN thin films PY - 2005 DO - https://doi.org/10.1016/j.surfcoat.2005.02.091 SN - 0257-8972 VL - 200 IS - 1-4 SP - 250 EP - 253 PB - Elsevier Science CY - Lausanne AN - OPUS4-10865 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Unger, Wolfgang A1 - Swaraj, Sufal A1 - Oran, Umut A1 - Lippitz, Andreas A1 - Schulze, Rolf-Dieter T1 - NEXAFS - spectroscopy on plasma-polymerized films prepared from organic molecules (ethylene, allyl alcohol, styrene) KW - Plasma KW - Beschichtung KW - Organische Filme KW - Röntgenabsorptionsspektroskopie PY - 2004 UR - http://www.helmholtz-berlin.de/media/media/oea/web/pr_webseite/druckschriften/berichte/bessy/annualreport2003.pdf#page=297 SN - 0179-4159 SP - 297 EP - 299 PB - Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung CY - Berlin AN - OPUS4-3478 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Swaraj, Sufal A1 - Oran, Umut A1 - Lippitz, Andreas A1 - Friedrich, Jörg Florian A1 - Unger, Wolfgang T1 - Aging of Plasma-Deposited Films Prepared from Organic Monomers N2 - Plasma-deposited polymer films were prepared from organic molecules and investigated using near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) for aging effects after exposure to air. Results from the investigation of homopolymers are summarized. Primarily the effect of the deposition parameters duty cycle and power are dealt with. The effect of the deposition parameter pressure is briefly discussed. An example to show the effect of feed gas composition on the aging of plasma polymerized ethylene/allyl alcohol and styrene/allyl alcohol copolymer is also given. In general, change in content of unsaturated or aromatic species, change in concentration of monomer functionality, and change in the oxygen content was observed in the plasma polymerized films on aging. KW - Plasma copolymer KW - ESCA/XPS KW - NEXAFS KW - Plasma polymerization PY - 2007 SN - 1612-8850 SN - 1612-8869 VL - 4 IS - S1 SP - S784 EP - S789 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-11934 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Swaraj, Sufal A1 - Oran, Umut A1 - Lippitz, Andreas A1 - Schulze, Rolf-Dieter A1 - Friedrich, Jörg Florian A1 - Unger, Wolfgang T1 - Surface Analysis of Plasma-Deposited Polymer Films, 4 - In situ Characterization of Plasma-Deposited Ethylene Films by XPS and NEXAFS N2 - XPS and NEXAFS spectroscopy were used for the chemical characterization of pulsed plasma-deposited ethylene films before and after exposure to ambient air. The influence of external plasma parameters on the spectroscopic results was investigated. Information on the chemical character of the plasma-polymerized films, such as the regularity of the primary structure, the amount of long-living radicals, and branching or cross-linking or both was derived from this data. Irregularity and radical concentration for post-plasma reactions of the plasma-deposited films increased with the duty cycle or power. A decreased level of monomer fragmentation and, consequently, an increase in regularity is partially concluded from the experimental data when the monomer pressure is increased. The concentration of surface radicals available for post-plasma reactions also increased with monomer pressure. The correlation found between the degree of the post-plasma oxygen incorporation and the variation of the various external parameters agreed with earlier ToF-SSIMS findings. KW - ESCA/XPS KW - NEXAFS KW - Plasma polymerization KW - Polyethylene (PE) KW - Thin films PY - 2005 DO - https://doi.org/10.1002/ppap.200400070 SN - 1612-8850 SN - 1612-8869 VL - 2 IS - 4 SP - 310 EP - 318 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-11940 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Wolfgang A1 - Swaraj, Sufal A1 - Oran, Umut A1 - Lippitz, Andreas T1 - Radio frequency (r.f.) plasma-deposited polymer films: influence of external plasma parameters as viewed by comprehensive in-situ surface chemical analysis by XAS, XPS and ToF-SIMS N2 - The formation of plasma-deposited materials made from organic molecules is a technologically attractive way to obtain films with unique properties, e.g. adhesion, wettability, conductivity or selected chemical functionalization. A detailed chemical characterization of these films is a great challenge for the analyst because of the co-existence of a large number of chemical species in plasma-deposited films. We investigated these types of organic films using photoelectron spectroscopy for chemical analysis (ESCA, XPS), near edge X-ray absorption fine structure (NEXAFS) spectroscopy at synchrotron radiation source BESSY II and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). A dedicated plasma preparation chamber was designed and added to the main analysis chamber of the respective spectrometers. This approach offers the possibility of studying plasma-deposited films without exposure to air before analysis (often called in-situ analysis) and the influence of post-plasma reactions, i.e. the ageing process. The present investigations are aimed at finding correlations between basic chemical properties of the deposited films and the plasma deposition parameters, e.g. duty cycle in pulsed plasmas and the power of discharge. KW - Plasma deposition KW - NEXAFS KW - XPS KW - ToF-SIMS KW - Plasma parameter PY - 2006 DO - https://doi.org/10.1002/sia.2158 SN - 0142-2421 SN - 1096-9918 VL - 38 IS - 4 SP - 522 EP - 525 PB - Wiley CY - Chichester AN - OPUS4-12271 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Oran, Umut A1 - Swaraj, Sufal A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Surface analysis of Plasma Deposited Polymer Films, 7: "In situ" Characterization of Plasma Deposited Allylamine Films by ToF-SSIMS, XPS and NEXAFS Spectroscopy N2 - Plasma deposited allylamine films were studied by in situ ToF-SSIMS, XPS and NEXAFS Spectroscopy before exposure to ambient air. The influence of external plasma parameters such as duty cycle, plasma power, and monomer flow rate on (i) unsaturation, (ii) branching and cross-linking, (iii) nitrogen surface concentration and (iv) retention of amino groups was investigated. Harder plasma conditions, which can be obtained when high duty cycles, high plasma power, and low monomer flow rates are employed, increase the unsaturated, branched and cross-linked character of the plasma deposited films, while the surface concentration of N as well as the retention of the monomer's amino group decrease. As proven by NEXAFS findings and cross-checked by ToF-SSIMS results, the allylamine monomer's primary amino groups are partially transformed into other nitrogen functionalities during its plasma polymerization. Amongst them imines and nitriles are the conversion products with the highest probabilities of formation. Another conversion channel is the formation of nitrogen species not participating in the film growth. This is the reason for an increased N loss in plasma deposited allylamine films as observed independently by XPS and ToF-SSIMS when the plasma parameters are changed from mild to hard. KW - Allylamine KW - NEXAFS KW - Plasma polymerization KW - ToF-SSIMS KW - XPS PY - 2006 DO - https://doi.org/10.1002/ppap.200500168 SN - 1612-8850 SN - 1612-8869 VL - 3 IS - 3 SP - 288 EP - 298 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-12272 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Swaraj, Sufal A1 - Oran, Umut A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - NEXAFS - spectroscopy on freshly prepared and aged plasma-polymerised films PY - 2006 UR - http://www.helmholtz-berlin.de/media/media/oea/web/pr_webseite/druckschriften/berichte/bessy/annualreport2005.pdf#page=322 SN - 0179-4159 SP - 320 EP - 322 PB - Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung CY - Berlin AN - OPUS4-12804 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Swaraj, Sufal A1 - Oran, Umut A1 - Lippitz, Andreas A1 - Friedrich, Jörg Florian A1 - Unger, Wolfgang T1 - Study of influence of external plasma parameters on plasma polymerised films prepared from organic molecules (acrylic acid, allyl alcohol, allyl amine) using XPS and NEXAFS N2 - Plasma polymerised films of acrylic acid, allyl alcohol and allyl amine were prepared and studied by XPS (X-ray photoelectron spectroscopy) and XAS (X-ray absorption spectroscopy). The influence of external plasma parameters on certain chemical aspects of the films was investigated. The use of XPS and NEXAFS (near edge X-ray absorption fine structure) as complimentary tools in the surface characterisation of thin films has been highlighted. Certain chemical aspects of the plasma polymerised films such as presence of ROCdouble bond; length as m-dashO in the case of plasma polymerised acrylic acid films, presence of RCdouble bond; length as m-dashO and RC–OR bonds in case of plasma polymerised allyl alcohol films and presence of RCdouble bond; length as m-dashN and C?N in case of plasma polymerised allyl amine films were studied. The concentration of ROCdouble bond; length as m-dashO species was found to decrease with increase in r.f. duty cycle in the case of plasma polymerised acrylic acid films. In case of plasma polymerised allyl alcohol films there is a decrease in the concentration of RCdouble bond; length as m-dashO species and increase in the concentration of RC–OR species at higher pressures, while in the case of plasma polymerised allyl amine films the concentration of RCdouble bond; length as m-dashN and C?N increases at higher powers, with an increase in C?N more pronounced at higher powers. KW - Plasma polymerization KW - NEXAFS KW - XPS KW - Plasma parameter PY - 2005 DO - https://doi.org/10.1016/j.surfcoat.2005.01.083 SN - 0257-8972 VL - 200 IS - 1-4 SP - 494 EP - 497 PB - Elsevier Science CY - Lausanne AN - OPUS4-11045 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Unger, Wolfgang A1 - Oran, Umut A1 - Swaraj, Sufal A1 - Lippitz, Andreas ED - Chandra, T. T1 - Ageing studies of plasma deposited organic films by surface chemical analysis (ESCA, ToF-SIMS, XAS) T2 - 5th International Conference on Processing & Manufacturing of Advanced Materials CY - Vancouver, Canada DA - 2006-07-04 KW - Plasma polymerized organic films KW - Ageing phenomena KW - ESCA KW - TOF-SIMS KW - XAS PY - 2007 SN - 0-87849-428-6 SN - 0255-5476 N1 - Serientitel: Materials science forum – Series title: Materials science forum VL - 539-543 IS - 539/543 SP - 623 EP - 628 PB - Trans Tech Publ. CY - Stafa-Zürich AN - OPUS4-14446 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Swaraj, Sufal A1 - Oran, Umut A1 - Friedrich, Jörg Florian A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Surface Chemical Analysis of Plasma-Deposited Copolymer Films Prepared from Feed Gas Mixtures of Ethylene or Styrene with Allyl Alcohol N2 - Plasma deposited styrene/allyl alcohol and ethylene/allyl alcohol copolymer films were prepared and characterized using XPS, NEXAFS and ToF-SIMS. The relative partial flow rates of the co-monomers are used as deposition process parameters to vary and all other process parameters were constrained to conditions optimized for retention of functional groups. By doing this it is possible to control certain chemical properties of the copolymer films such as unsaturation, oxygen and hydroxyl group relative surface contents. The aging behavior of the plasma copolymer films on air was studied, too. Non-linear variations of relative oxygen contents, contents of C—OR species and contents of carbonyl species are obtained vs. variation of feed gas composition for both monomer combinations. The chemical character of the plasma copolymer films varies between the limits given by the respective plasma homopolymers. The observed non-linear correlations are discussed in terms of approaches developed for classic radical copolymerization. The aging behavior of the different plasma copolymers films depends on the feed gas composition. Principally these aging phenomena known from plasma polymer aging studies of that respective monomer which dominates the character of the plasma copolymer are observed. KW - Plasma polymers KW - Plasma copolymers KW - XPS KW - NEXAFS KW - Allyl alcohol KW - ESCA/XPS KW - Plasma polymerization KW - ToF-SIMS PY - 2007 SN - 1612-8850 SN - 1612-8869 VL - 4 IS - 4 SP - 376 EP - 389 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-14846 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Swaraj, Sufal A1 - Oran, Umut A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Surface Chemical Analysis of Plasma-Deposited Copolymer Films Prepared from Feed Gas Mixtures of Ethylene or Styrene with Allylamine N2 - Plasma deposited ethylene/allylamine and styrene/allylamine copolymer films were prepared and analyzed using XPS, NEXAFS and ToF-SIMS. The relative partial flow rate of the each monomer was used as the variable deposition parameter, while the other deposition parameters were kept constant at optimized values for the retention of functional groups. The effect of the variation in the relative partial flow rates of co-monomers on various chemical aspects of the films like unsaturation, nitrogen retention and branching was investigated revealing several non-linear correlations. This observation is taken as an indication for chemical copolymerization processes during film deposition. An attempt is made to compare these non-linear correlations with approaches which have been developed for classic radical copolymerization processes. The aging behavior of these plasma copolymer films was also studied; the results indicated a stabilization against oxidation in comparison to the aging of allylamine plasma homopolymers. KW - Ethylene-allylamine copolymer KW - ESCA KW - NEXAFS KW - Plasma polymerization KW - Styrene-allylamine copolymer KW - Surface characterization KW - TOF-SIMS KW - XPS PY - 2008 DO - https://doi.org/10.1002/ppap.200700106 SN - 1612-8850 SN - 1612-8869 VL - 5 IS - 1 SP - 92 EP - 104 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-16466 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietrich, Paul A1 - Horlacher, T. A1 - Girard-Lauriault, Pierre-Luc A1 - Gross, Thomas A1 - Lippitz, Andreas A1 - Min, Hyegeun A1 - Wirth, Thomas A1 - Castelli, R. A1 - Seeberger, P. A1 - Unger, Wolfgang T1 - Multimethod chemical characterization of carbohydrate-functionalized surfaces N2 - A combined XPS, NEXAFS, and ToF-SIMS chemical surface characterization of carbohydrate-functionalized gold and glass surfaces is presented. Spot shape and chemical composition across a spot surface are provided by surface-sensitive methods as ToF-SIMS and XPS, used in their imaging modes. Moreover, the feasibility of this multimethod approach to control relevant production steps of a carbohydrate microarray prototype is demonstrated. KW - Carbohydrates KW - Microarrays KW - Self-assembled monolayers KW - XPS KW - NEXAFS KW - ToF-SIMS PY - 2011 DO - https://doi.org/10.1080/07328303.2011.615181 SN - 0732-8303 VL - 30 IS - 4-6 SP - 361 EP - 372 PB - Taylor & Francis CY - London [u.a.] AN - OPUS4-24874 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Girard-Lauriault, Pierre-Luc A1 - Gross, Thomas A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Chemical and elemental depth profiling of very thin organic layers by constant kinetic energy XPS: a new synchrotron XPS analysis strategy N2 - We present a new synchrotron X-ray photoelectron spectroscopy strategy for surface chemical analysis of materials. Our approach is based on the acquisition of photoelectron spectra at constant kinetic energies with the help of a tunable synchrotron X-radiation source. This ensures both constant and tunable information depth for all elements in a very thin organic layer. Many of the problems known to XPS depth profiling using laboratory equipment are thereby avoided. Using our methodology, the 95% information depth, z95%, can be tuned down to about 0.7 nm in organic materials. The upper limit in our study at the HE-SGM monochromator dipole magnet beamline at the synchrotron radiation source BESSY II is about 4.3 nm. Elemental quantification is achieved through relative sensitivity factors (RSF) specific to the measurement conditions, determined either with the help of calculated photoionization cross sections and inelastic mean free paths or experimentally. The potential of the technique is demonstrated for the in-depth analysis of plasma deposited nitrogen-rich organic thin films used in biomedical applications. PY - 2012 DO - https://doi.org/10.1021/ac300585q SN - 0003-2700 SN - 1520-6882 VL - 84 IS - 14 SP - 5984 EP - 5991 PB - American Chemical Society CY - Washington, DC AN - OPUS4-26299 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lippitz, Andreas A1 - Friedrich, Jörg Florian A1 - Unger, Wolfgang T1 - Plasma bromination of HOPG surfaces: a NEXAFS and synchrotron XPS study N2 - Br bonding on plasma brominated graphite surfaces has been studied by using Near Edge X-ray Absorption Fine Structure (NEXAFS) and X-ray Photoelectron Spectroscopy (XPS). Br2 and bromoform were used as plasma gases in an r.f. cw low pressure plasma process. Kr plasma had been used to study separately the physical and chemical plasma etching effects. At early steps of plasma bromination which lead to only small XPS Br surface concentration values a quick decay of aromaticity has been observed. At low Br surface concentration radical or even electrophilic addition of bromine onto sp2 carbon atoms is discussed as the dominating reaction pathway. At higher Br surface concentrations the inherent formation of sp3 defects in the graphene network by chemical etching processes promotes nucleophilic substitution of bromine at sp3 carbons as a competing reaction pathway. Both reaction pathways lead to C–Br species characterized by the same Br 3d XPS binding energy. However more than one Br 3d component in XP spectra has been found at lower Br2 plasma induced Br surface concentrations and complexation of bromine at HOPG is assumed as a third way of interaction with Br2 plasma. KW - HOPG KW - Graphite KW - Plasma bromination KW - Low pressure plasma KW - NEXAFS KW - XPS PY - 2013 DO - https://doi.org/10.1016/j.susc.2013.01.020 SN - 0039-6028 VL - 611 SP - L1 EP - L7 PB - Elsevier CY - Amsterdam AN - OPUS4-27928 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Darlatt, Erik A1 - Nefedov, A. A1 - Traulsen, C.H.-H. A1 - Poppenberg, J. A1 - Richter, S. A1 - Dietrich, Paul A1 - Lippitz, Andreas A1 - Illgen, René A1 - Kühn, Julius A1 - Schalley, C.A. A1 - Wöll, Ch. A1 - Unger, Wolfgang T1 - Interperetation of experimental N K NEXAFS of azide, 1,2,3-triazole and terpyridyl groups by DFT spectrum simulations N2 - Experimental N K-edge NEXAFS data of surface immobilized azide, 1,2,3-triazole and terpyridyl groups are interpreted with the help of DFT spectrum simulations. Assignments of π* resonances in experimental N K-edge NEXAFS spectra to nitrogen atoms within these functional groups have been made. The azide was immobilized on gold as the head group of a thiol SAM, 1,2,3-triazole was formed on this SAM by click reaction and terpyridyl groups were introduced as substituents of the acetylene used for the click reaction. For azide-terminated molecules, DFT spectrum simulations are found to be useful to find measurement conditions delivering experimental N K-edge NEXAFS data with negligible X-ray damage. The 1,2,3-triazole group is found to be rather stable under X-ray irradiation. KW - N K-edge NEXAFS KW - XANES KW - Surface click chemistry KW - Density functional theory KW - Azide KW - 1,2,3-Triazole PY - 2012 DO - https://doi.org/10.1016/j.elspec.2012.09.008 SN - 0368-2048 SN - 1873-2526 VL - 185 IS - 12 SP - 621 EP - 624 PB - Elsevier CY - Amsterdam AN - OPUS4-27774 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gross, Thomas A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Charakterisierung von Siliziumoxidschichten auf Silizium mit ESCA - Ein Beitrag zur Präszisionsbestimmung der Avogadro-Konstanten T2 - EMASS 2000 CY - Berlin, Deutschland DA - 2000-11-10 PY - 2000 AN - OPUS4-1020 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Wolfgang A1 - Gross, Thomas A1 - Lippitz, Andreas A1 - Güttler, B. T1 - Uncertainty in measurement of overlayer thickness of thermally oxidized silicon using x-ray photoelectron spectroscopy N2 - Overlayers of SiO2 (nominally 4, 6 and 8 nm thick) on silicon, prepared by thermal oxidation, were investigated using x-ray photoelectron spectroscopy (XPS). The thickness of these overlayers was obtained from a measurement of the photoelectron intensities originating from the substrate and the oxide overlayer by applying an appropriate quantitative model. The uncertainty budget of that thickness measurement method is given. The relative combined standard uncertainty of the method was found to be 15%. The effective attenuation lengths or the corresponding electron inelastic mean free paths are of considerable importance for both the estimated values of overlayer thickness and combined standard uncertainties. The XPS results were compared with ellipsometry data. KW - XPS KW - ESCA KW - Uncertainty KW - Overlayer KW - SiO2 PY - 2000 DO - https://doi.org/10.1002/1096-9918(200012)29:12<891::AID-SIA943>3.0.CO;2-A SN - 0142-2421 SN - 1096-9918 IS - 29 SP - 891 EP - 894 PB - Wiley CY - Chichester AN - OPUS4-1075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Boese, O. A1 - Kemnitz, E. T1 - y-Al2O3 by Au 4f7/2-referenced XPS and XAES N2 - Powder x-ray diffraction (XRD) defined -Al2O3 has been investigated by x-ray photoelectron spectroscopy (XPS) and x-ray excited Auger electron spectroscopy (XAES). The Au 4f7/2 orbital is used for static charge referencing. This feature originates from well-defined and chemically inert 20 nm highly dispersed gold particles deposited on the sample surface. The particles, with a narrow particle size distribution, were obtained from a highly purified colloidal solution (sodium concentration below 1 mg/l). This procedure allows a determination of gold-referenced XPS and XAES data sets. ©2001 American Vacuum Society. KW - Au 4f referenced XPS data KW - Aluminium KW - Oxide PY - 2001 UR - http://scitation.aip.org/vsearch/servlet/VerityServlet?KEY=SSSPEN&ONLINE=YES&smode=strresults&sort=chron&maxdisp=25&threshold=0&possible1zone=article&possible4=lippitz&possible4zone=author&bool4=and&fromyear=2001&OUTLOG=NO&viewabs=SSSPEN&key=DISPLAY&docID DO - https://doi.org/10.1116/11.20020305 SN - 1055-5269 SN - 1520-8575 VL - 8 IS - 1-4 SP - 214 EP - 219 PB - AIP CY - Woodbury, NY AN - OPUS4-1910 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Wolfgang A1 - Böse, Olaf A1 - Gross, Thomas A1 - Lippitz, Andreas A1 - Gelius, U. ED - Boehlig, H. T1 - Results of a VAMAS TWA 2 inter-laboratory test experimen - Evaluation of static charge stabilization and determination methods in XPS on non-conducting samples T2 - 11th Conference on Applied Surface Analysis (AOFA) CY - Leipzig, Germany DA - 2000-09-24 PY - 2000 SN - 0169-4332 VL - 179 IS - 1 PB - Elsevier CY - Amsterdam AN - OPUS4-978 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Friedrich, Jörg Florian A1 - Retzko, Iris A1 - Kühn, Gerhard A1 - Unger, Wolfgang A1 - Lippitz, Andreas ED - Mittal, K. T1 - Metal doped plasma polymer films T2 - 7th Symposium on Metallized Plastics CY - Newark, NJ, USA DA - 1999-12-02 KW - Plasma polymer KW - r.f. pulsed plasma KW - Conducting films KW - Metal-polymer interface PY - 2001 SN - 90-6764-340-8 VL - 7 SP - 117 EP - 142 PB - VSP CY - Utrecht AN - OPUS4-929 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nietzold, Carolin A1 - Dietrich, Paul A1 - Holzweber, M. A1 - Lippitz, Andreas A1 - Kamalakumar, A. A1 - Blanchard, V. A1 - Ivanov-Pankov, S. A1 - Weigel, W. A1 - Panne, Ulrich A1 - Unger, Wolfgang T1 - Surface chemical characterization of model glycan surfaces and shelf life studies of glycan microarrays using XPS, NEXAFS spectroscopy, ToF-SIMS and fluorescence scanning N2 - Biomedical applications, including functional biomaterials, carbohydrate-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 glycan arrays is a crucial factor. Herein we report on approaches for surface and interface characterization relevant to the needs of production of glycan microarrays which were tested using model carbohydrate surfaces. For detailed characterization of glycan model surfaces we used a combination of X-ray photoelectron spectroscopy (XPS), near edge X-ray absorption fine structure spectroscopy (NEXAFS) and ToF SIMS which are complementary techniques of surface chemical analysis. Links to fluorescence spectroscopy often used for characterization in the microarray community were established as well. In detail, amine-reactive silicon oxide and glass surfaces were used for anchoring oligosaccharides with an amino linker. The amount of surface bound carbohydrates was estimated by X-ray photoelectron spectroscopy (XPS). Glycan immobilization was investigated using lectins, which are glycan-binding molecules. A shelf life study of model glycan microarrays on epoxy-coated glass surfaces was done over a period of 160 days under different storage conditions utilizing fluorescence, ToF-SIMS and XPS analysis. It was shown that glycan activity of the models used can be maintained at least for half a year of storage at 4 °C. KW - Glycan microarray KW - XPS KW - NEXAFS KW - ToF-SIMS KW - Fluorescence PY - 2018 UR - https://www.sciencedirect.com/science/article/pii/S0169433218320300?via%3Dihub DO - https://doi.org/10.1016/j.apsusc.2018.07.133 SN - 0169-4332 SN - 1873-5584 VL - 459 SP - 860 EP - 873 PB - Elsevier B.V. AN - OPUS4-46212 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Geng, Sh. A1 - Unger, Wolfgang A1 - Lippitz, Andreas A1 - Erdmann, J. A1 - Gorsler, H.-V. T1 - Plasma functionalization and reorientation of macromolecules at polymer surfaces KW - Plasma KW - Polymer KW - Monolayer KW - Einschichtsystem KW - NEXAFS KW - Spektroskopie KW - Oberflächenanalyse PY - 1995 SN - 0257-8972 VL - 74-75 SP - 664 EP - 669 PB - Elsevier Science CY - Lausanne AN - OPUS4-627 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Wigan, L. A1 - Unger, Wolfgang A1 - Lippitz, Andreas A1 - Erdmann, J. A1 - Gorsler, H.-V. T1 - Barrier properties of plasma and chemically fluorinated polypropylene and polyethyleneterephthalate N2 - The functionalization, perfluorination or an coating of polypropylene (PP) and polyethyleneterephthalate (PET) surfaces in different plasma atmospheres and in an F[2] + N[2] gas mixture were investigated. The aim of this work was to form a barrier layer against solvent and fuel permeation. Typical test solvents were n-pentane, toluene, tetrachloroethylene and mixtures of n-pentane and methanol. The permeation was gravimetrically measured. The permeation of the solvent mixtures was analyzed by mass spectrometry and Fourier transform IR spectroscopy. The permeation of the solvent mixtures through the plasma-modified polymer samples was associated with increased absorption of polar solvent components in the polymer film. The thickness of the plasma-fluorinated PP surface layer was 10-100 nm and that of chemically fluorinated PP about 5000 nm. Nearly the same barrier efficiency was measured for both plasma- and chemically fluorinated samples. T2 - International Conference on Plasma Surface Engineering No. 4 CY - Garmisch-Partenkirchen, Germany DA - 1994-09-19 KW - Plasma KW - Fluor KW - Plasmapolymer KW - Sperrschicht KW - Permeation PY - 1995 UR - http://cat.inist.fr/?aModele=afficheN&cpsidt=3158319 SN - 0257-8972 VL - 74-75 IS - 1-3 SP - 910 EP - 918 PB - Elsevier Science CY - Lausanne AN - OPUS4-628 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lippitz, Andreas A1 - Koprinarov, Ivaylo A1 - Friedrich, Jörg Florian A1 - Unger, Wolfgang A1 - Weiss, K. A1 - Wöll, Ch. T1 - Surface analysis of metaillized poly(bisphenol A cabonate) films by x-ray absorption spectroscopy (NEXAFS) KW - NEXAFS KW - Röntgenadsorptionsspektroskopie KW - Oberflächenanalyse KW - Film, metallisiert KW - Polymeroberfläche PY - 1996 SN - 0032-3861 SN - 1873-2291 VL - 37 IS - 14 SP - 3157 EP - 3160 PB - Springer CY - Berlin AN - OPUS4-649 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lippitz, Andreas A1 - Friedrich, Jörg Florian A1 - Unger, Wolfgang A1 - Schertel, A. A1 - Wöll, Ch. T1 - Surface analysis of partially crystalline and amorphous poly(ethylene terephthalate) samples by x-ray absorption spectroscopy (NEXAFS) KW - NEXAFS KW - Röntgenadsorptionsspektroskopie KW - Oberflächenanalyse KW - Polymeroberfläche PY - 1996 SN - 0032-3861 SN - 1873-2291 VL - 37 IS - 14 SP - 3151 EP - 3155 PB - Springer CY - Berlin AN - OPUS4-650 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grohmann, I. A1 - Kemnitz, E. A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Curve Fitting of Cr2p Photoelectron Spectra of Cr2O3 and CrF3 KW - Photoelektronenspektroskopie KW - Kurvenglättung KW - Chrom PY - 1995 SN - 0142-2421 SN - 1096-9918 VL - 23 SP - 887 EP - 891 PB - Wiley CY - Chichester AN - OPUS4-678 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Lippitz, Andreas A1 - Koprinarov, Ivaylo A1 - Friedrich, Jörg Florian A1 - Unger, Wolfgang A1 - Schertel, A. A1 - Wöll, Ch. T1 - NEXAFS analysis of a plasma treated, partially crystalline poly(ehtylene terephtalate) surface KW - NEXAFS KW - Röntgenstrukturanalyse KW - Oberflächen behandeln KW - Plasma PY - 1996 SN - 0179-4159 SP - 279 EP - 281 PB - Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung CY - Berlin AN - OPUS4-681 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Forkel, K. A1 - Kosslick, H. A1 - Lippitz, Andreas A1 - Rolle, S. ED - Dufour, L.-C. T1 - Investigation of thermal properties of Fe75Cr5P8C10Si2 metal-metalloid glassy T2 - XIIIth International Symposium ; 13th International Symposium on the Reactivity of Solids CY - Hamburg, Germany DA - 1996-09-08 KW - Glasoberfläche KW - Beanspruchung, thermisch PY - 1996 PB - North-Holland CY - Amsterdam AN - OPUS4-686 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Wolfgang A1 - Lippitz, Andreas A1 - Gross, Thomas A1 - Friedrich, Jörg Florian A1 - Wöll, Ch. A1 - Nick, L. T1 - The Use of Octadecyltrichlorosilane Self-Assembled Layers as a Model for the Assessment of Plasma Treatment and Metallization Effects on Polyolefins N2 - Self-assembled octadecyltrichlorosilane (CH3(CH2)17SiCl3, OTS) films were deposited on an oxidized silicon wafer. They were carefully exposed to a low-pressure oxygen direct current (dc) plasma and/or Cr vapor. Subsequently, they were characterized by X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, and atomic force microscopy. Detailed information on the oxygen functionalization and the molecular conformation of the OTS films was obtained. The main result was that functionalization conditions can be found where the order of the film remains almost unaffected. Similarly, Cr evaporation of pure OTS films revealed only slight effects on the order in the film. Cr evaporation of an ordered but functionalized OTS film immediately changes its state toward a fully isotropic one. In the course of interaction, oxygen sites at the surface of the functionalized OTS film are reduced whereas Cr becomes oxidized. A redox reaction scheme is proposed for this interfacial reaction. Finally, it is concluded that the given study should be of importance for advanced plasma processing of polyolefins. KW - NEXAFS KW - OTS Self-Assembled Layers PY - 1999 DO - https://doi.org/10.1021/la981174l SN - 0743-7463 SN - 1520-5827 VL - 15 IS - 4 SP - 1161 EP - 1166 PB - American Chemical Society CY - Washington, DC AN - OPUS4-808 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Friedrich, Jörg Florian A1 - Koprinarov, Ivaylo A1 - Giebler, Rainer A1 - Lippitz, Andreas A1 - Unger, Wolfgang T1 - Reactions and Intermediates at the Metal-Polymer Interface as Observed by XPS and NEXAFS Spectroscopy KW - XPS KW - NEXAFS KW - Interfacial polymer-metal redox reactions KW - Chromium-polymer intermediates KW - Near edge X-ray absorption fine structure spectroscopy KW - Adhesion KW - Polymer-metal bonds KW - Polymer-aluminium bonds KW - Polymer-copper bonds PY - 1999 SN - 0021-8464 SN - 1545-5823 VL - 71 SP - 297 EP - 321 PB - Gordon & Breach CY - New York, NY AN - OPUS4-798 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Gross, Thomas A1 - Güttler, J. T1 - Neues vom Urkilogramm KW - Oberflächenanalytik PY - 1999 SN - 0341-5163 SN - 1521-3854 VL - 47 IS - 7 SP - 784 EP - 786 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-791 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nietzold, Carolin A1 - Dietrich, Paul A1 - Lippitz, Andreas A1 - Panne, Ulrich A1 - Unger, Wolfgang T1 - Cyclodextrin – ferrocene host – guest complexes on silicon oxide surfaces N2 - Research on carbohydrate based interactions with proteins, nucleic acids or antibodies has gained increased interest in the last years especially in clinical diagnosis or drug development. The efficiency of diagnostic interfaces depends upon the number of probe molecules, e.g. carbohydrates. The control of surface parameters as density and distribution of immobilized carbohydrates is essential for a reliable interaction with protein analytes. A controlled production of biomolecular interfaces can be reached by a stepwise quality control during buildup of these biointerfaces. Here, ß-amino-cyclodextrin molecules were attached to amine-reactive silicon oxide surfaces via click chemistry to construct a model biosensor surface. The amount of surface bound carbohydrates was determined indirectly after chemical derivatization with 4-(trifluoromethyl)-benzylamine (TFMBA). Moreover, these surfaces were used to form host-guest complexes of ferrocene (guest) and β-cyclodextrin (host) moieties to mimic the target binding (sensing) of the model biosensor. Surface chemical analysis of all steps during biosensor construction was performed using X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). Our approach widens the possibilities to generate switchable surfaces based on ß-Cyclodextrin surfaces for biosensor applications. KW - ß-amino-cyclodextrin KW - Ferrocene KW - Guest complexe KW - XPS KW - NEXAFS PY - 2016 DO - https://doi.org/10.1002/sia.5958 SN - 0142-2421 SN - 1096-9918 VL - 48 IS - 7 SP - 606 EP - 610 PB - Wiley AN - OPUS4-36856 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tan, K. H. A1 - Sattari, S. A1 - Donskyi, Ievgen A1 - Cuellar-Camacho, J. L. A1 - Cheng, C. A1 - Schwibbert, Karin A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Gorbushina, Anna A1 - Adeli, M. A1 - Haag, R. T1 - Functionalized 2D nanomaterials with switchable binding to investigate graphene–bacteria interactions N2 - Graphene and its derivatives have recently attracted much attention for sensing and deactivating pathogens. However, the mechanism of multivalent interactions at the graphene–pathogen interface is not fully understood. Since different physicochemical parameters of graphene play a role at this interface, control over graphene’s structure is necessary to study the mechanism of these interactions. In this work, different graphene derivatives and also zwitterionic graphene nanomaterials (ZGNMs) were synthesized with defined exposure, in terms of polymer coverage and functionality, and isoelectric points. Then, the switchable interactions of these nanomaterials with E. coli and Bacillus cereus were investigated to study the validity of the generally proposed “trapping” and “nano-knives” mechanisms for inactivating bacteria by graphene derivatives. It was found that the antibacterial activity of graphene derivatives strongly depends on the accessible area, i.e. edges and basal plane of sheets and tightness of their agglomerations. Our data clearly confirm the authenticity of “trapping” and “nano-knives” mechanisms for the antibacterial activity of graphene sheets. KW - XPS KW - Graphene KW - Graphene–bacteria interaction PY - 2018 DO - https://doi.org/10.1039/c8nr01347k SN - 2040-3364 SN - 2040-3372 VL - 10 IS - 20 SP - 9525 EP - 9537 PB - RSC CY - London AN - OPUS4-45084 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Min, Hyegeun A1 - Girard-Lauriault, Pierre-Luc A1 - Gross, Thomas A1 - Lippitz, Andreas A1 - Dietrich, Paul A1 - Unger, Wolfgang T1 - Ambient-ageing processes in amine self-assembled monolayers on microarray slides as studied by ToF-SIMS with principal component analysis, XPS, and NEXAFS spectroscopy N2 - We investigated the ageing of amine-terminated self-assembled monolayers (amine-SAMs) on different silica substrates due to exposure to different ambient gases, pressures, and/or temperatures using time-of-flight secondary ion mass spectrometry (ToF-SIMS) with principal component analysis and complementary methods of surface analysis as X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS). The goal of this study is to examine the durability of primary amine groups of amine-SAMs stored in a user laboratory prior to being used as supports for biomolecule immobilization and other applications. We prepared amine-SAMs on the native oxides of silicon wafers and glass slides using 3-aminopropyl triethoxysilane, by using optimized conditions such as anhydrous organic solvent and reaction time scale of hours to avoid multilayer growth. Selected commercial amine-SAM slides have been investigated, too. When the amine-SAMs are exposed to air, oxygen incorporation occurs, followed by formation of amide groups. The formation of oxygen species due to ageing was proved by ToFSIMS, XPS, and NEXAFS findings such as CNO- secondary ion emission at m/z 42, observation of the N 1s HNC=O component peak at 400.2–400.3 eV in XPS, and, last but not least, by formation of a π*(HNC=O) resonance at 401 eV in the N K-edge X-ray absorption spectrum. It is concluded that the used multi-method approach comprising complementary ToF-SIMS, XPS, and NEXAFS analyses is well suited for a thorough study of chemical aspects of ageing phenomena of amine-SAM surfaces. KW - Amine-SAM KW - Ageing process KW - ToF-SIMS KW - NEXAFS KW - XPS PY - 2012 DO - https://doi.org/10.1007/s00216-012-5862-5 SN - 1618-2642 SN - 1618-2650 VL - 403 IS - 2 SP - 613 EP - 623 PB - Springer CY - Berlin AN - OPUS4-25829 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Guday, G. A1 - Donskyi, Ievgen A1 - Gholami, M. F. A1 - Algara-Siller, G. A1 - Witte, F. A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Paulus, B. A1 - Rabe, J. A1 - Adeli, M. A1 - Haag, R. T1 - Scalable Production of Nanographene and Doping via Nondestructive Covalent Functionalization N2 - A new method for top‐down, one‐pot, gram‐scale production of high quality nanographene by incubating graphite in a dilute sodium hypochlorite solution at only 40 °C is reported here. The produced sheets have only 4 at% oxygen content, comparable with nanographene grown by chemical vapor deposition. The nanographene sheets are covalently functionalized using a nondestructive nitrene [2+1] cycloaddition reaction that preserves their π‐conjugated system. Statistical analyses of Raman spectroscopy and X‐ray photoelectron spectroscopy indicate a low number of sp3 carbon atoms on the order of 2% before and 4% after covalent functionalization. The nanographene sheets are significantly more conductive than conventionally prepared nanographene oxide, and conductivity further increases after covalent functionalization. The observed doping effects and theoretical studies suggest sp2 hybridization for the carbon atoms involved in the [2+1] cycloaddition reaction leading to preservation of the π‐conjugated system and enhancing conductivity via n‐type doping through the bridging N‐atom. These methods are easily scalable, which opens the door to a mild and efficient process to produce high quality nanographenes and covalently functionalize them while retaining or improving their physicochemical properties. KW - Graphene KW - XPS KW - NEXAFS PY - 2019 DO - https://doi.org/10.1002/smll.201805430 VL - 15 IS - 12 SP - 1805430 PB - WILEY-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-48021 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Abad Andrade, Carlos Enrique A1 - Florek, S. A1 - Becker-Ross, H. A1 - Huang, M.-D. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Lippitz, Andreas A1 - Hodoroaba, Vasile-Dan A1 - Schmid, Thomas A1 - Heinrich, Hans-Joachim A1 - Recknagel, Sebastian A1 - Jakubowski, Norbert A1 - Panne, Ulrich T1 - Zirconium permanent modifiers for graphite furnaces used in absorption spectrometry: understanding their structure and mechanism of action N2 - The mechanism of action of zirconium permanent modifiers on graphite surfaces was investigated in order to understand its influence on the analytical signal in atomic and molecular absorption spectrometry (AAS/MAS). For this, the molecule formation of CaF was studied, which is used for the indirect analytical determination of fluorine in high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS). The kinetics of this reaction was established by monitoring its molecular spectrum at different atomisation temperatures. An Arrhenius plot showed a pseudo-first order reaction with respect to fluorine (n = 1). An intermediate state was isolated, and its structure was elucidated by spectroscopic methods: scanning electron microscopy with energy dispersive X-ray spectroscopy (SEMEDX), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XANES and EXAFS), and Raman microspectroscopy. We propose here a mechanism, where ZrO2 acts as a heterogeneous catalyst: after a pyrolytic step, an intermediate state of ZrO(OCaF) is activated, and at higher temperatures, CaF(g) is released from the zirconium-coated graphite surface. No evidence of the formation of zirconium carbide was found. Consequently, as the CaF formation is catalysed by a heterogeneous catalyst, surface modifications with ZrO2 nanoparticles and ZrO xerogels were investigated in order to increase the surface area. Their influence was evaluated in the molecule formation of CaF, CaCl, CaBr, and CaI. Graphite furnace modification with zirconium oxide nanoparticles proves to be the best choice for fluorine analysis with a signal enhancement of more than eleven times with respect a non-coated graphite furnace. However, the influence of zirconium modifications in the analytical signals of Cl, and I is lower than the F signals or even negative in case of the Br. Understanding zirconium modifiers as heterogeneous catalysts offers a new perspective to AAS and MAS, and reveals the potential of surface analytical methods for development of improved permanent modifiers and graphite furnace coatings. KW - Zirconium KW - HR-CS-MAS KW - Graphite furnace KW - Nanoparticles KW - Xerogel KW - Calcium monofluoride KW - Absorption spectrometry PY - 2018 UR - https://pubs.rsc.org/en/content/articlelanding/2018/ja/c8ja00190a DO - https://doi.org/10.1039/C8JA00190A SN - 0267-9477 VL - 33 IS - 12 SP - 2034 EP - 2042 PB - Royal Society of Chemistry AN - OPUS4-46775 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Donskyi, Ievgen A1 - Chen, Y. A1 - Nickl, Philip A1 - Guday, G. A1 - Qiao, H. A1 - Achasi, K. A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Böttcher, C. A1 - Chen, W. A1 - Adeli, M. A1 - Haag, R. T1 - Self-degrading graphene sheets for tumor therapy N2 - Low biodegradability of graphene derivatives and related health risks are the main limiting factors for their in vivo biomedical applications. Here, we present the synthesis of enzyme-functionalized graphene sheets with self-degrading properties under physiological conditions and their applications in Tumor therapy. The synergistic enzyme cascade glucose oxidase and myeloperoxidase are covalently conjugated to the surface of graphene sheets and two-dimensional (2D) platforms are obtained that can produce sodium hypochlorite from glucose. The enzyme-functionalized graphene sheets with up to 289 nm average size are degraded into small pieces (≤40 nm) by incubation under physiological conditions for 24 h. Biodegradable graphene sheets are further loaded with doxorubicin and their ability for Tumor therapy is evaluated in vitro and in vivo. The laser-triggered release of doxorubicin in combination with the enzymatic activity of the functionalized graphene sheets results in a synergistic antitumor activity. Taking advantage of their neutrophil-like activity, fast biodegradability, high photo- and chemotherapeutic effects, the novel two-dimensional nanoplatforms can be used for tumor therapeutic applications. KW - Graphene KW - Self-degrading KW - Thumor therapy KW - XPS KW - NEXAFS PY - 2020 DO - https://doi.org/10.1039/d0nr02159h SP - 1 EP - 12 PB - The Royal Society of Chemistry AN - OPUS4-50978 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinrich, Thomas A1 - Darlatt, Erik A1 - Lippitz, Andreas A1 - Müller, S. A1 - Schalley, C. A1 - Unger, Wolfgang T1 - Systematic XP and NEXAFS spectroscopy studies of (ter-)pyridineterminated self-assembled monolayers and their addressability for functional molecules N2 - The chemical composition of surfaces functionalized with self-assembled monolayers (SAMs) is an important parameter that determines their performance in a broad range of applications, from immobilizing molecular machines to initiation and growth control of MOFs (Metal-Organic Frameworks). In this article, a critical Survey of XPS (X-ray photoelectron spectroscopy) and NEXAFS (near edge X-ray absorption fine structure) spectroscopy data for pyridine-functionalized monolayers on gold surfaces is presented to compile correlations that have been indiscernible before. Monolayers with aromatic backbones are compared to monolayers with aliphatic backbones. Monolayers with pyridine end-groups are compared to mixed monolayers formed terpyridine-functionalized by molecules end-groups and non-functionalized molecules. Thiol-oxidation during ageing of the SAMs in air is addressed. And finally, the addressability of the SAMs for the deposition of metal-ions and organic molecules is investigated and compared. This work consequently delivers a comprehensive set of spectroscopic data of (ter-)pyridine-terminated SAMs and their performance as template for the preparation of functional multilayers of macrocycles exhibiting a preferential orientation. KW - (ter-)pyridineterminated self-assembled monolayer KW - X-ray Photoelectron Spectroscopy (XPS) KW - NEXAFS PY - 2019 DO - https://doi.org/10.1016/j.elspec.2019.03.011 VL - 233 SP - 28 EP - 37 PB - Elsevier B.V. AN - OPUS4-48018 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Holzweber, Markus A1 - Lippitz, Andreas A1 - Hesse, R. A1 - Denecke, R. A1 - Werner, W. A1 - Unger, Wolfgang T1 - The use of ionic liquids for the determination of the spectrometer transmission function in X-ray photoelectron spectroscopy (XPS) N2 - The uncertainty of measurement in quantitative XPS analysis can be reduced by using a calibrated spectrometer transmission function T (E), which is usually determined by taking spectra from Au, Ag, Cu and Ge elemental reference materials. However, this approach is quite time-consuming due to required sample preparation steps like sputter cleaning etc., and the relatively big number of samples to be measured. This contribution proposes the use of the ionic liquids [C2C1im][NTf2] and [C3C1im][NTf2] as reference materials for a determination of T(E). These multi-elemental samples deliver five intensive photoemission peaks, F 1s, O 1s, N 1s, C 1s and S 2p, in an energy window from 160 eV to 700 eV which is of specific interest for applications of quantitative XPS for surface chemical analysis of soft matter, one of the major applications of XPS. KW - Quantitative XPS KW - Ionic liquid KW - Transmission function PY - 2019 DO - https://doi.org/10.1016/j.elspec.2019.03.008 VL - 233 SP - 51 EP - 56 PB - Elsevier B.V. AN - OPUS4-48019 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Park, J. A1 - Kim, G. B. A1 - Lippitz, Andreas A1 - Kim, Y. M. A1 - Jung, D. A1 - Unger, Wolfgang A1 - Kim, Y.-P. A1 - Lee, T. G. T1 - Plasma-polymerized antifouling biochips for label-free measurement of protease activity in cell culture media N2 - We report polyethylene glycol (PEG)-grafting antifouling surfaces using a plasma copolymerized (PcP) technique to monitor protease activity in complex media. By varying the mixing ratio of the PEG and ethylenediamine (EDA) precursors, the PcP-PEG-EDA (PcP-PE) film was able to easily control surface amine density with good preservation of the internal PEG structure. We found that nonspecific protein adsorption was dramatically reduced in serum-containing media on the PcP-PE films, as opposed to that on plasma polymerized-EDA (PP-E) films without PEG. When SPR sensor chips coated with PcP-PE film were employed to detect protease activity, biotinylated luciferase probes (luciferase-peptide-biotin) on streptavidin-conjugated SPR chips enabled real-time and label-free measurement of matrix metalloproteinase activity in cell culture media. Owing to its excellent antifouling ability, this newly developed method boasts minimal nonspecific binding and can serve as a biochip platform to promote a wide range of applications in the biological field. KW - Polyethylene glycol (PEG)-grafting antifouling surface KW - Biochip KW - ATR-FTIR spectroscopy KW - XPS KW - NEXAFS KW - Plasma PY - 2019 DO - https://doi.org/10.1016/j.snb.2018.10.123 SN - 0925-4005 VL - 281 SP - 527 EP - 534 PB - Elsevier B.V. AN - OPUS4-46463 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Donskyi, Ievgen A1 - Azab, W. A1 - Cuellar-Camach, J. L. A1 - Guday, G. A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Osterrieder, K. A1 - Adeli, M. A1 - Haag, R. T1 - Functionalized nanographene sheets with high antiviral activity through synergistic electrostatic and hydrophobic interactions N2 - As resistance to traditional drugs emerges for treatment of Virus infections, the need for new methods for virus inhibition increases. Graphene derivatives with large surface areas have shown strong activity against different viruses. However, the inability of current synthetic protocols to accurately manipulate the structure of graphene sheets in order to control their antiviral activity remains a major challenge. In this work, a series of graphene derivatives with defined polyglycerol sulfate and fatty amine functionalities have been synthesized and their interactions with herpes simplex Virus type 1 (HSV-1) are investigated. While electrostatic interactions between polyglycerol sulfate and virus particles trigger the binding of graphene to virus, alkyl chains induce a high antiviral activity by secondary hydrophobic interactions. Among graphene sheets with a broad range of alkyl chains, (C3–C18), the C12-functionalized sheets showed the highest antiviral activity, indicating the optimum synergistic effect between electrostatic and hydrophobic interactions, but this derivative was toxic against the Vero cell line. In contrast, sheets functionalized with C6- and C9-alkyl chains showed low toxicity against Vero cells and a synergistic Inhibition of HSV-1. This study shows that antiviral agents against HSV-1 can be obtained by controlled and stepwise functionalization of graphene sheets and may be developed into antiviral agents for future biomedical applications. KW - Functionalized nanographene KW - X-ray Photoelectron Spectroscopy (XPS) KW - NEXAFS KW - Antiviral activity PY - 2019 DO - https://doi.org/10.1039/c9nr05273a SN - 2040-3364 VL - 11 IS - 34 SP - 15804 EP - 15809 PB - The Royal Society of Chemistry AN - OPUS4-48807 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietrich, Paul M. A1 - Lange, Nele A1 - Lippitz, Andreas A1 - Holzweber, Markus A1 - Kulak, N. A1 - Unger, Wolfgang T1 - Click chemistry on silicon nitride for biosensor fabrication N2 - Biosensors are of essential importance in medical and biological diagnostics. Often, they are produced using silane chemistry on glass or silicon oxide surfaces. However, controlling that silane chemistry is challenging. Here, we present an alternative strategy to form functional organic layers and biosensors on silicon Nitride (Si3N4). H-terminated Si3N4 films are used to generate reactive azide groups by various azidation methods. Biomolecular probes can then be immobilized using click chemistry reactions with the azide groups and due to its high sensitivity in XPS a fluorine-substituted test alkyne was utilized to optimize click chemistry conditions. After that a biotinylated alkyne was clicked to Si3N4 surfaces followed by immobilization of streptavidin as analyte in a model assay. The functionalized surfaces were thoroughly characterized by surface chemical analysis using X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS)spectroscopy. KW - Biosensors KW - H-terminated Si3N4 films KW - Click chemistry KW - X-ray photoelectron spectroscopy KW - Near edge X-ray absorption fine structure KW - Streptavidin binding PY - 2019 DO - https://doi.org/10.1016/j.apsusc.2019.03.002 SN - 0169-4332 VL - 481 SP - 10 EP - 15 PB - Elsevier B.V. AN - OPUS4-48634 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heinrich, Thomas A1 - Traulsen, Christoph Hans-Henning A1 - Darlatt, Erik A1 - Richter, S. A1 - Poppenberg, J. A1 - Traulsen, N.L. A1 - Linder, I. A1 - Lippitz, Andreas A1 - Dietrich, Paul A1 - Dib, B. A1 - Unger, Wolfgang A1 - Schalley, C.A. T1 - The versatility of 'Click' reactions at surfaces: Molecular recognition at interfaces N2 - In order to investigate molecular recognition on surfaces, an azide-functionalized monolayer was deposited on gold. The monolayer was characterized by X-ray photoelectron spectroscopy (XPS) and angle-resolved near-edge X-ray absorption fine structure (NEXAFS) experiments and the decomposition of the azide upon irradiation with X-ray beams was investigated. Subsequently, various alkyne-functionalized host and guest molecules were attached to the azide by 1,3-dipolar cycloaddition. These modified surfaces and their host–guest chemistry were analysed by XPS and angle-resolved NEXAFS. The reversibility of guest binding was shown for one example as a proof of principle. KW - 'Click' reaction KW - Azide-terminated surfaces KW - SAMs KW - Host guest molecules KW - Molecular recognition at interfaces PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-306463 DO - https://doi.org/10.1039/C4RA01730G SN - 2046-2069 VL - 4 IS - 34 SP - 17694 EP - 17702 PB - RSC Publishing CY - London AN - OPUS4-30646 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schwarz, F. A1 - Heinrich, Thomas A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Schalley, C. T1 - A photoswitchable rotaxane operating in monolayers on solid support N2 - A novel photoswitchable rotaxane was synthesised and its switching behaviour in solution was analysed with NMR and UV-Vis. A monolayer of rotaxanes was deposited on glass surfaces and the on-surface photoswitching was investigated. Angle-resolved NEXAFS spectra revealed a preferential orientation that reversibly changes upon switching. KW - XPS KW - NEXAFS KW - Photoswitchable rotaxane KW - Self assembly PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-386814 DO - https://doi.org/10.1039/c6cc08586e SN - 0022-4936 SN - 1364-548X SN - 0009-241x SN - 1359-7345 VL - 52 IS - 100 SP - 14458 EP - 14461 PB - Royal Society of Chemistry (RSC) AN - OPUS4-38681 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 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 - JOUR A1 - Abbas, F. A1 - Donskyi, Ievgen A1 - Gholami, M. A1 - Ziem, B. A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Böttcher, C. A1 - Rabe, J. A1 - Haag, R. A1 - Adeli, M. T1 - Controlled covalent functionalization of thermally reduced graphene oxide to generate defined bifunctional 2D nanomaterials N2 - A controlled, reproducible, gram-scale method is reported for the covalent functionalization of graphene Sheets by a one-pot nitrene [2+1] cycloaddition reaction under mild conditions. The reaction between commercially available 2,4,6-trichloro-1,3,5-triazine and sodium azide with thermally reduced graphene oxide (TRGO) results in defined dichlorotriazine-functionalized sheets. The different reactivities of the chlorine substituents on the functionalized graphene allow stepwise post-modification by manipulating the temperature. This new method provides unique access to defined bifunctional 2D nanomaterials, as exemplified by chiral surfaces and multifunctional hybrid architectures. KW - Graphene oxide KW - Bifunctional 2D nanomaterials KW - XPS KW - NEXAFS KW - AFM PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-394789 DO - https://doi.org/10.1002/ange.201612422 SN - 1433-7851 VL - 56 IS - 10 SP - 2675 EP - 2679 PB - Wiley-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-39478 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Wolfgang A1 - Beiranvand, Z. A1 - Kakanejadifard, A. A1 - Donskyi, Ievgen A1 - Faghani, A. A1 - Tu, Z. A1 - Lippitz, Andreas A1 - Sasanpour, P. A1 - Maschietto, F. A1 - Paulus, B. A1 - Haag, R. A1 - Adeli, M. T1 - Functionalization of fullerene at room temperature: toward new carbon vectors with improved physicochemical properties N2 - In this work, fullerene has been functionalized with cyanuric Chloride at room temperature by a nitrene mediated [2 + 1] cycloaddition reaction. The adduct after functionalization is inherently in the form of azafulleroid and shows broad UV absorption in the wavelength range of 200–800 nm, as well as photothermal conversion and fluorescence with a high quantum yield. KW - Functionalization of fullerenes KW - XPS KW - NEXAFS PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-387076 DO - https://doi.org/10.1039/c6ra23419d SN - 2046-2069 VL - 6 IS - 114 SP - 112771 EP - 112775 PB - Royal Society of Chemistry (RSC) AN - OPUS4-38707 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -