TY - JOUR A1 - Yegen, E. A1 - Zimmermann, Uwe A1 - Unger, Wolfgang A1 - Braun, T. T1 - C-F bond cleavage during derivatization reactions of amino groups with TFBA and PFB at plasma-processed organic surfaces? JF - Plasma processes and polymers N2 - Chemical derivatization XPS is used for the quantitative determination of amines at conventional organic surfaces, and it is also applied to plasma-processed aminated surfaces. When using TFBA and PFB as derivatization reagents for tagging primary amino groups, unexpected fluorine species were observed in the second case. The existence of reaction pathways other than those expected for amine derivatization with PFB or TFBA has to be assumed. This phenomenon is tentatively interpreted as the result of C—F bond cleavage during derivatization reactions of TFBA and PFB at plasma-polymerized allylamine and other plasma-processed aminated surfaces. As a consequence, quantification procedures based on derivatization by PFB or TFBA will underestimate amine surface concentrations. KW - Aminated surfaces KW - Chemical derivatization KW - ESCA KW - Plasma polymers KW - XPS PY - 2009 DO - https://doi.org/10.1002/ppap.200800100 SN - 1612-8850 SN - 1612-8869 VL - 6 IS - 1 SP - 11 EP - 16 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-18686 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Seah, M.P. A1 - Unger, Wolfgang A1 - Wang, H. A1 - Jordaan, W. A1 - Gross, Thomas A1 - Dura, J.A. A1 - Moon, D.W. A1 - Totarong, P. A1 - Krumrey, M. A1 - Hauert, R. A1 - Zhiqiang, M. T1 - Ultra-thin SiO2 on Si IX: absolute measurements of the amount of silicon oxide as a thickness of SiO2 on Si JF - Surface and interface analysis N2 - Results from a study conducted between National Metrology Institutes (NMIs) for the measurements of the absolute thicknesses of ultra-thin layers of SiO2 on Si are reported. These results are from a key comparison and associated pilot study under the auspices of the Consultative Committee for Amount of Substance. ´Amount of substance´ may be expressed in many ways, and here the measurand is the thickness of the silicon oxide layers with nominal thicknesses in the range 1.5-8 nm on Si substrates, expressed as the thickness of SiO2. Separate samples were provided to each institute in containers that limited the carbonaceous contamination to approximately < 0.3 nm. The SiO2 samples were of ultra-thin on (100) and (111) orientated wafers of Si. The measurements from the laboratories which participated in the study were conducted using ellipsometry, neutron reflectivity, X-ray photoelectron spectroscopy or X-ray reflectivity, guided by the protocol developed in an earlier pilot study. A very minor correction was made in the different samples that each laboratory received. Where appropriate, method offset values attributed to the effects of contaminations, from the earlier pilot study, were subtracted. Values for the key comparison reference values (agreed best values from a Consultative Committee study) and their associated uncertainties for these samples are then made from the weighted means and the expanded weighted standard deviations of the means of these data. These results show a dramatic improvement on previous comparisons, leading to 95% uncertainties in the range 0.09-0.27 nm, equivalent to 0.4-1.0 monolayers over the 1.5-8.0 nm nominal thickness range studied. If the sample-to-sample uncertainty is reduced from its maximum estimate to the most likely value, these uncertainties reduce to 0.05-0.25 nm or ~1.4% relative standard uncertainties. The best results achieve ~1% relative standard uncertainty. It is concluded that XPS has now been made fully traceable to the SI, for ultra-thin thermal SiO2 on Si layers, by calibration using wavelength methods in an approach that may be extended to other material systems. KW - Attenuation length KW - Calibration KW - Silicon dioxide KW - Thickness KW - Ultra-thin oxide PY - 2009 DO - https://doi.org/10.1002/sia.3045 SN - 0142-2421 SN - 1096-9918 VL - 41 IS - 5 SP - 430 EP - 439 PB - Wiley CY - Chichester AN - OPUS4-19246 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gross, Thomas A1 - Kühn, Gerhard A1 - Unger, Wolfgang T1 - Photoelectron spectroscopy on organic surfaces: X-ray degradation of oxygen-plasma-treated and chemically reduced poly(propylene) surfaces in comparison to conventional polymers JF - Surface and interface analysis N2 - The X-ray-induced sample damage during mono XPS analysis of an oxygen-plasma-oxidized and subsequently wet-chemically reduced poly(propylene) film was investigated as a showcase for plasma-modified or plasma-deposited samples. By doing this, the degradation index approach as introduced by Beamson and Briggs in the Scienta ESCA300 high-resolution XPS database of organic polymers has been adopted. As to be expected, the sample degrades by loosing oxygen as revealed by observation of decreasing O/C and COR/Csum ratios. However, the X-ray degradation indices are definitely higher than those of conventional reference polymers. Moreover, the COR/Csum degradation index is significantly higher in comparison with one obtained for the O/C ratio. In that context, there is no difference between the plasma sample and a conventional poly(vinyl alcohol) polymer. It is concluded that for reliable quantitative surface chemical analysis, the quality of spectra in terms of acquisition times must be optimized aimed to a minimization of X-ray degradation. Finally, it is proposed to describe the photon flux of an X-ray gun in an XPS experiment, which defines the degradation rate at the end, by using the sample current simply measured with a carefully grounded sputter-cleaned reference silver sample. KW - Photoelectron spectroscopy KW - ESCA/XPS KW - Surfaces KW - Surface modification KW - Poly(propylene) (PP) KW - Plasma treatment KW - X-ray KW - Degradation PY - 2009 DO - https://doi.org/10.1002/sia.3024 SN - 0142-2421 SN - 1096-9918 VL - 41 IS - 5 SP - 445 EP - 448 PB - Wiley CY - Chichester AN - OPUS4-19252 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Graf, Nora A1 - Gross, Thomas A1 - Wirth, Thomas A1 - Weigel, W. A1 - Unger, Wolfgang T1 - Application of XPS and ToF-SIMS for surface chemical analysis of DNA microarrays and their substrates JF - Analytical and bioanalytical chemistry N2 - The chemical composition of the functional surfaces of substrates used for microarrays is one of the important parameters that determine the quality of a microarray experiment. In addition to the commonly used contact angle measurements to determine the wettability of functionalized supports, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) are more specific methods to elucidate details about the chemical surface constitution. XPS yields information about the atomic composition of the surface, whereas from ToF-SIMS, information on the molecular species on the surface can be concluded. Applied on printed DNA microarrays, both techniques provide impressive chemical images down to the micrometer scale and can be utilized for label-free spot detection and characterization. Detailed information about the chemical constitution of single spots of microarrays can be obtained by high-resolution XPS imaging. KW - Microarrays KW - Surface analysis KW - XPS KW - ToF-SIMS KW - Chemical imaging PY - 2009 DO - https://doi.org/10.1007/s00216-009-2599-x SN - 1618-2642 SN - 1618-2650 VL - 393 IS - 8 SP - 1907 EP - 1912 PB - Springer CY - Berlin AN - OPUS4-19245 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 JF - Chemistry of materials 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 - CONF A1 - Unger, Wolfgang T1 - Metrological Challenges in Surface Micro/Nano Analysis (SMNA) T2 - 13th European Conference on Apllications of Surface and Interface Analysis, ECASIA 09 T2 - 13th European Conference on Apllications of Surface and Interface Analysis, ECASIA 09 CY - Antalya, Turkey DA - 2009-10-18 PY - 2009 AN - OPUS4-20201 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Wolfgang T1 - Metrological Challenges in Surface Micro/Nano Analysis (SMNA): The Activities of the CCQM Surface Analysis Working Group T2 - 5th Brazilian Congress of Metrology T2 - 5th Brazilian Congress of Metrology CY - Salvador, Brazil DA - 2009-11-09 PY - 2009 AN - OPUS4-20731 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Wolfgang T1 - Joint SAWG/BAWG Meeting 2009: Introduction of Activities of CCQM Surface Analysis Working Group (SAWG) in Bioanalysis T2 - CCQM Working Groups Meeting 2009 T2 - CCQM Working Groups Meeting 2009 CY - Rio de Janeiro, Brazil DA - 2009-11-03 PY - 2009 AN - OPUS4-20732 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Unger, Wolfgang A1 - Gross, Thomas ED - John C. Rivière, ED - Sverre Myhra, T1 - Catalyst characterization T2 - Handbook of surface and interface analysis - Methods for Problem-Solving KW - Catalyst KW - Surface KW - Analysis KW - XPS KW - ESCA KW - SIMS PY - 2009 SN - 978-0-8493-7558-3 VL - 2nd Edition IS - Chapter 16 SP - 501 EP - 528 PB - CRC Press CY - Boca Raton, FL, USA AN - OPUS4-19602 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Wolfgang T1 - Surface Analysis at the Nano Scale: Metrological Challenges and Progress in Standardization T2 - Workshop: Application of Standards within Nanometrology at the EuroNanoForum 2009 T2 - Workshop: Application of Standards within Nanometrology at the EuroNanoForum 2009 CY - Prague, Czech Republic DA - 2009-06-02 PY - 2009 AN - OPUS4-19564 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -