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 - Dietrich, Paul A1 - Treu, Dieter A1 - Kalbe, Henryk A1 - Krumrey, M. A1 - Gross, Thomas A1 - Marti, K. A1 - Unger, Wolfgang T1 - Experimental determination of the effective attenuation length of palladium 3d 5/2 photoelectrons in a magnetron sputtered Pd nanolayer N2 - An electron effective attenuation length (EAL) of 1.68nm for Al Kα excited Pd 3d 5/2 photoelectrons with a kinetic energy of 1.152 keV has been determined experimentally using a sputtered Pd film deposited on an ultra flat fused quartz substrate. The film thickness was reduced by Ar ion sputtering several times in order to obtain different Pd film thicknesses which are used to determine experimental EAL values. These results are compared to data generated by using a Simulation of Electron Spectra for Surface Analysis (SESSA) simulation using an inelastic mean free path (IMFP) calculated with the Tanuma–Powell–Penn (TPP)-2M formula and with ‘elastic scattering on and off’. Contributions to the uncertainty budget related to the experimental approach are discussed in detail. Proposals on how to further improve the approach are suggested. KW - Pd 3d KW - Electron effective attenuation length KW - XPS PY - 2017 UR - http://onlinelibrary.wiley.com/doi/10.1002/sia.6141/abstract?campaign=woletoc DO - https://doi.org/10.1002/sia.6141 SN - 0142-2421 SN - 1096-9918 VL - 49 IS - 5 SP - 464 EP - 468 PB - John Wiley & Sons, Ltd AN - OPUS4-39682 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Baytekin, H.T. A1 - Baytekin, B. A1 - Schulz, a. A1 - Springer, A. A1 - Gross, Thomas A1 - Unger, Wolfgang A1 - Artamonova, M. A1 - Schlecht, S. A1 - Lentz, D. A1 - Schalley, C.A. T1 - Metallo-supramolecular nanospheres via hierarchical self-assembly N2 - A novel coordination oligo/polymer is synthesized by metal-directed self-assembly from equimolar amounts of the (dppp)M(OTf)2 precursor complexes (dppp = bis-(diphenylphosphino)-propane, OTf = triflate; M = PdII or M = PtII) and banana-shaped bidentate dipyridyl ligands. The assemblies were characterized by ESI mass spectrometry and NMR spectroscopy. The analysis of the cloudy suspension prepared by dissolving the coordination polymer in aqueous methanol solutions indicates nanosized spherical objects to form. Evidence for vesicle formation from these metallo-supramolecular oligomers comes from (cryogenic) transmission electron microscopy (TEM, cryo-TEM). Atomic force microscopy revealed stable nanospheres on hydrophilic mica and monolayer formation on hydrophobic highly oriented pyrolitic graphite (HOPG) substrates. On mica, also torus-shaped object were observed, which are rationalized by vesicles that opened during the drying procedure and released the internal solvent. Elemental analysis of the nanoassemblies by X-ray photoelectron spectroscopy (XPS) indicates uncoordinated and coordinated pyridines in the coordination polymers that form the nanospheres. Various control experiments using different metal centers and modified ligands support the conclusions. KW - Self-assembly KW - Metallo-supramolecular chemistry KW - Coordination polymers KW - Vesicles KW - Electron microscopy KW - Nano-materials PY - 2009 DO - https://doi.org/10.1021/cm900642p SN - 0897-4756 SN - 1520-5002 VL - 21 IS - 13 SP - 2980 EP - 2992 PB - American Chemical Society CY - Washington, DC AN - OPUS4-19638 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 - JOUR A1 - Dietrich, Paul A1 - Horlacher, T. A1 - Gross, Thomas A1 - Wirth, Thomas A1 - Castelli, R. A1 - Shard, A.G. A1 - Alexander, M. A1 - Seeberger, P. H. A1 - Unger, Wolfgang T1 - Surface analytical characterization of carbohydrate microarrays N2 - Microarrays are a versatile platform for diagnostics and high-throughput analysis. Carbohydrate microarrays are valuable tools to investigate interactions with other molecules since many glycans are involved in fundamental biological processes. A combined X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) surface analysis was used to investigate the basic steps in the production of carbohydrate microarrays. The preparation included coupling of a thiol-terminated mannoside to maleimide-functionalized glass surfaces derived from γ-aminopropyl silane (GAPS) slides. XPS results clearly demonstrate successful chemical modification in each fabrication step, and ToF-SIMS imaging revealed immobilized carbohydrates in the spotted regions of the final microarray. KW - Carbohydrates KW - Microarrays KW - XPS KW - ToF-SIMS KW - Nona-mannoside KW - Maleimide surfaces KW - Surface analysis PY - 2010 DO - https://doi.org/10.1002/sia.3255 SN - 0142-2421 SN - 1096-9918 VL - 42 SP - 1188 EP - 1192 PB - Wiley CY - Chichester AN - OPUS4-21500 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gross, Thomas A1 - Pippig, F. A1 - Merz, B. A1 - Merz, R. A1 - Vohrer, U. A1 - Mix, Renate A1 - Steffen, H. A1 - Bremser, Wolfram A1 - Unger, Wolfgang T1 - Determination of OH groups at plasma oxidised poly(propylene) by TFAA chemical derivatisation XPS: an inter-laboratory comparison N2 - A first inter-laboratory comparison was conducted to demonstrate and document the capability of interested laboratories to measure the fraction of C—OH species on a plasma oxidised poly(propylene) sample by using a chemical derivatisation XPS approach. This report presents the results from that inter-laboratory comparison and includes the data received for the measured values and their associated standard deviations of laboratory means, at a 95% confidence level. The measurements were guided by a protocol developed within the group before and summarised shortly in the paper. Standard deviations that may characterise the state-of-the-art for the nominally simple and rather often practised case of TFAA chemical derivatisation XPS of C—OH species on a plasma oxidised polyolefin surface are calculated following ISO 5725-2:1994. The main conclusion is that the associated degree of equivalence reached by the participating laboratories in this comparison is still low. Further research to improve chemical derivatisation XPS protocols is mandatory. KW - Chemical derivatisation KW - ESCA/XPS KW - Inter-laboratory comparison KW - Photoelectron spectroscopy (PES) KW - Poly(propylene) (PP) PY - 2010 DO - https://doi.org/10.1002/ppap.200900142 SN - 1612-8850 SN - 1612-8869 VL - 7 IS - 6 SP - 494 EP - 503 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-21678 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Girard-Lauriault, Pierre-Luc A1 - Retzko, Iris A1 - Swaraj, Sufal A1 - Matsubayashi, N. A1 - Gross, Thomas A1 - Mix, Renate A1 - Unger, Wolfgang T1 - Non-destructive sub-surface chemical characterization of air-exposed plasma polymers by energy-resolved XPS KW - Plasma polymers KW - Synchrotron XPS KW - Depth profiling KW - Derivatisation PY - 2010 DO - https://doi.org/10.1002/ppap.200900130 SN - 1612-8850 SN - 1612-8869 VL - 7 IS - 6 SP - 474 EP - 481 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-21711 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Baytekin, H. Tarik A1 - Wirth, Thomas A1 - Gross, Thomas A1 - Sahre, Mario A1 - Unger, Wolfgang A1 - Theisen, J. A1 - Schmidt, M. T1 - Surface analytical characterization of micro-fluidic devices hot embossed in polymer wafers: Surface chemistry and wettability N2 - Recently, time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) instrumentation has been used to address areas of interest within micro-fluidic devices providing full access to the surface chemistry established at the bottom of micro-channels therein. After careful calibration, information on surface chemistry as obtained by ToF-SIMS or XPS can be interpreted in terms of wettability expressed as contact angles which are then characteristic for the inner walls of micro-channels. Standard contact angle measurement is not applicable in micro-channels. The approach has been demonstrated to be successful with two different micro-fluidic devices hot embossed into high-end quality poly(methyl methacrylate) (PMMA) or Polycarbonate wafers. A pre-selected surface chemistry at micro-channel walls can be established by plasma technologies but ageing and rinsing effects have to be under control. A combination of ToF-SIMS, XPS and contact angle measurement techniques has been demonstrated to provide the required information. Finally, it is shown by ToF-SIMS and XPS analysis that in the production of micro-fluidic parts during practical processing using hot embossing technologies, material originating from cover foils will reside on the polymer wafer's surface. Moreover, residues of releasing agents as silicone oil used during processing can be detected by ToF-SIMS. Both cover foil residues and silicones are issues of trouble shooting in micro-fluidics because they will change contact angles efficiently. KW - Micro-fluidic device KW - PMMA KW - Polycarbonate KW - Plasma treatment KW - Wettability KW - ToF-SIMS KW - XPS PY - 2010 DO - https://doi.org/10.1002/sia.3149 SN - 0142-2421 SN - 1096-9918 VL - 42 IS - 8 SP - 1417 EP - 1431 PB - Wiley CY - Chichester AN - OPUS4-21712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Baytekin, H.T. A1 - Wirth, Thomas A1 - Gross, Thomas A1 - Treu, Dieter A1 - Sahre, Mario A1 - Theisen, J. A1 - Schmidt, M. A1 - Unger, Wolfgang T1 - Determination of wettability of surface-modified hot-embossed polycarbonate wafers used in microfluidic device fabrication via XPS and ToF-SIMS N2 - The wettability of the surfaces inside the microchannels of a microfluidic device is an important property considering a liquid flows through them. Contact angle measurements usually applied to test the wettability of surfaces cannot be used for an analysis of microchannel walls within microfluidic devices. A workaround is the use of surface analytical methods, which are able to reach points of interest in microchannels and may provide information on the surface chemistry established there. In calibrating these methods by using flat polymer wafers, where the contact angle can be measured as usual, data measured in real microchannels can be evaluated in terms of wetting properties. Reference wafers of bisphenol-A polycarbonate, a polymeric material that is often used in fluidic microdevice fabrication, were treated under different oxygen plasma conditions. The modified surfaces were characterized by using XPS, time of flight (ToF)-SIMS and atomic force microscope (AFM). Surface chemistry and surface topography have been correlated with contact angle measurements. In addition, effects of ageing or rinsing after plasma treatment have also been investigated. KW - Oxygen plasma KW - Polycarbonate KW - XPS KW - ToF-SIMS KW - Principal component analysis PY - 2008 DO - https://doi.org/10.1002/sia.2724 SN - 0142-2421 SN - 1096-9918 VL - 40 IS - 3-4 SP - 358 EP - 363 PB - Wiley CY - Chichester AN - OPUS4-17340 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -