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 JF - Surface and interface analysis 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 - 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 JF - Langmuir 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 - 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 T2 - BESSY II Annual Report 2008 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 - 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 JF - Journal of carbohydrate chemistry 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 - 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 JF - Langmuir 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 - 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 JF - Analytical and bioanalytical chemistry 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 - 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 JF - Langmuir 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 -