TY - JOUR A1 - Belsey, N. A. A1 - Cant, D. J. H. A1 - Minelli, C. A1 - Araujo, J. R. A1 - Bock, B. A1 - Brüner, P. A1 - Castner, D. G. A1 - Ceccone, G. A1 - Counsell, J. D. P. A1 - Dietrich, Paul M. A1 - Engelhardt, M. H. A1 - Fearn, S. A1 - Galhardo, C. E. A1 - Kalbe, H. A1 - Kim, J. W. A1 - Lartundo-Rojas, L. A1 - Luftman, H. S. A1 - Nunney, T. S. A1 - Pseiner, J. A1 - Smith, E. F. A1 - Spampinato, V. A1 - Sturm, J. M. A1 - Thomas, A. G. A1 - Treacy, J. P. W. A1 - Veith, L. A1 - Wagstaffe, M. A1 - Wang, H. A1 - Wang, M. A1 - Wang, Y.-C. A1 - Werner, W. A1 - Yang, L. A1 - Shard, A. G. T1 - Versailles Project on Advanced Materials and Standards Interlaboratory Study on Measuring the Thickness and Chemistry of Nanoparticle Coatings Using XPS and LEIS N2 - We report the results of a Versailles Project on Advanced Materials and Standards (VAMAS) interlaboratory study on the measurement of the shell thickness and chemistry of nanoparticle coatings. Peptide-coated gold particles were supplied to laboratories in two forms: a colloidal suspension in pure water and particles dried onto a silicon wafer. Participants prepared and analyzed these samples using either X-ray photoelectron spectroscopy (XPS) or low energy ion scattering (LEIS). Careful data analysis revealed some significant sources of discrepancy, particularly for XPS. Degradation during transportation, storage, or sample preparation resulted in a variability in thickness of 53%. The calculation method chosen by XPS participants contributed a variability of 67%. However, variability of 12% was achieved for the samples deposited using a single method and by choosing photoelectron peaks that were not adversely affected by instrumental transmission effects. The study identified a need for more consistency in instrumental transmission functions and relative sensitivity factors since this contributed a variability of 33%. The results from the LEIS participants were more consistent, with variability of less than 10% in thickness, and this is mostly due to a common method of data analysis. The calculation was performed using a model developed for uniform, flat films, and some participants employed a correction factor to account for the sample geometry, which appears warranted based upon a simulation of LEIS data from one of the participants and comparison to the XPS results. KW - VAMAS KW - Interlaboratory Study KW - Nanoparticle coating KW - XPS KW - LEIS KW - shell thicknss and chemistry PY - 2016 UR - http://pubs.acs.org/doi/pdf/10.1021/acs.jpcc.6b06713 U6 - https://doi.org/10.1021/acs.jpcc.6b06713 IS - 120 SP - 24070 EP - 24079 PB - ACS Publications AN - OPUS4-38428 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reed, B. P. A1 - Cant, D.J.H. A1 - Spencer, J. A1 - Carmona-Carmona, A. J. A1 - Bushell, A. A1 - Herrara-Gómez, A. A1 - Kurokawa, A. A1 - Thissen, A. A1 - Thomas, A.G. A1 - Britton, A.J. A1 - Bernasik, A. A1 - Fuchs, A. A1 - Baddorf, A. P. A1 - Bock, B. A1 - Thellacker, B. A1 - Cheng, B. A1 - Castner, D.G. A1 - Morgan, D.J. A1 - Valley, D. A1 - Willneff, E.A. A1 - Smith, E.F. A1 - Nolot, E. A1 - Xie, F. A1 - Zorn, G. A1 - Smith, G.C. A1 - Yasukufu, H. A1 - Fenton, J. L. A1 - Chen, J. A1 - Counsell, J..D.P. A1 - Radnik, Jörg A1 - Gaskell, K.J. A1 - Artyushkova, K. A1 - Yang, L. A1 - Zhang, L. A1 - Eguchi, M. A1 - Walker, M. A1 - Hajdyla, M. A1 - Marzec, M.M. A1 - Linford, M.R. A1 - Kubota, N. A1 - Cartazar-Martínez, O. A1 - Dietrich, P. A1 - Satoh, R. A1 - Schroeder, S.L.M. A1 - Avval, T.G. A1 - Nagatomi, T. A1 - Fernandez, V. A1 - Lake, W. A1 - Azuma, Y. A1 - Yoshikawa, Y. A1 - Shard, A.G. T1 - Versailles Project on Advanced Materials and Standards interlaboratory study on intensity calibration for x-ray photoelectron spectroscopy instruments using low-density polyethylene N2 - We report the results of a Versailles Project on Advanced Materials and Standards interlaboratory study on the intensity scale calibration of x-ray photoelectron spectrometers using low-density polyethylene (LDPE) as an alternative material to gold, silver, and copper. An improved set of LDPE reference spectra, corrected for different instrument geometries using a quartz-monochromated Al Kα x-ray source, was developed using data provided by participants in this study. Using these new reference spectra, a transmission function was calculated for each dataset that participants provided. When compared to a similar calibration procedure using the NPL reference spectra for gold, the LDPE intensity calibration method achieves an absolute offset of ∼3.0% and a systematic deviation of ±6.5% on average across all participants. For spectra recorded at high pass energies (≥90 eV), values of absolute offset and systematic deviation are ∼5.8% and ±5.7%, respectively, whereas for spectra collected at lower pass energies (<90 eV), values of absolute offset and systematic deviation are ∼4.9% and ±8.8%, respectively; low pass energy spectra perform worse than the global average, in terms of systematic deviations, due to diminished count rates and signal-to-noise ratio. Differences in absolute offset are attributed to the surface roughness of the LDPE induced by sample preparation. We further assess the usability of LDPE as a secondary reference material and comment on its performance in the presence of issues such as variable dark noise, x-ray warm up times, inaccuracy at low count rates, and underlying spectrometer problems. In response to participant feedback and the results of the study, we provide an updated LDPE intensity calibration protocol to address the issues highlighted in the interlaboratory study. We also comment on the lack of implementation of a consistent and traceable intensity calibration method across the community of x-ray photoelectron spectroscopy (XPS) users and, therefore, propose a route to achieving this with the assistance of instrument manufacturers, metrology laboratories, and experts leading to an international standard for XPS intensity scale calibration. KW - X-ray photoelectron spectroscopy KW - Transmission function KW - Intensity scale calibration KW - Reference spectra KW - Low-density polyethylene (LDPE) PY - 2020 U6 - https://doi.org/10.1116/6.0000577 VL - 38 IS - 6 SP - 063208 AN - OPUS4-51655 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wetzel, Annica A1 - von der Au, Marcus A1 - Dietrich, P. M. A1 - Radnik, Jörg A1 - Özcan Sandikcioglu, Özlem A1 - Witt, Julia T1 - The comparison of the corrosion behavior of the CrCoNi medium entropy alloy and CrMnFeCoNi high entropy alloy N2 - This work presents the determination of the corrosion characteristics of CrCoNi (medium entropy alloy) and CrMnFeCoNi (high entropy alloy) in 0.1 M NaCl and 0.1 M H2SO4. The morphology and chemical composition of the oxide layers formed on CrCoNi and CrMnFeCoNi were comparatively analyzed by scanning Kelvin probe microscopy (SKPFM) and scanning electron microscopy (SEM) and supported with chemical analysis by means of inductively coupled plasma mass spectrometry (ICP-MS) and X-Ray photoelectron spectroscopy (XPS). The analysis of the 3p core level peaks showed that the oxide layer (native and after anodic passivation) on CrCoNi consisted mainly of Cr oxides, while the oxide layer on CrMnFeCoNi was primarily composed of a mixture of Cr and Fe oxides. In addition, XPS was utilized to assess the oxide layer thicknesses. These results were compared to the thicknesses obtained by means of electrochemical impedance spectroscopy (EIS), with both approaches yielding values up to about 4 nm depending on the electrolyte and the alloy. Cyclic polarization measurements indicated superior corrosion resistance of CrCoNi in both aqueous environments compared to CrMnFeCoNi, as well as to AISI 304 stainless steel. KW - Medium entropy alloy KW - High entropy alloy KW - SKPFM KW - XPS KW - Passivation KW - Corrosion PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-559902 SN - 0169-4332 VL - 601 SP - 1 EP - 10 PB - Elsevier B.V. AN - OPUS4-55990 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kjaervik, Marit A1 - Schwibbert, Karin A1 - Dietrich, P. A1 - Thissen, A. A1 - Unger, Wolfgang T1 - Surface characterisation of Escherichia coli under various conditions by near-ambient pressure XPS N2 - Bacteria are inherently in a hydrated state and therefore not compatible to ultra-high vacuum techniques such as XPS without prior sample preparation involving freeze drying or fast freezing. This has changed with the development of near-ambient pressure (NAP)-XPS, which makes it possible to characterise the bacterial surface with minimal sample preparation. This paper presents NAP-XPS measurements of Escherichia coli under various NAP conditions: at 11 mbar in a humid environment, at 2 mbar after drying in the chamber, pre-dried at 4 mbar, and at 1 mbar after overnight pumping at 10^−4 mbar. The high-resolution spectra of carbon, nitrogen, and oxygen are presented and found to be in general agreement with XPS measurements from freeze-dried and fast-frozen bacteria. However, it was found that the amount of carbon components associated with polysaccharides increases relative to aliphatic carbon during drying and increases further after overnight pumping. This implies that drying has an impact on the bacterial surface. T2 - European conference on applications of surface and interface analysis (ECASIA'17) CY - Montpellier, France DA - 24.09.2018 KW - Bacteria KW - E. coli KW - NAP-XPS PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-454047 SN - 0142-2421 SN - 1096-9918 VL - 50 IS - 11 SP - 996 EP - 1000 PB - John Wiley & Sons CY - Hoboken, New Jersey, USA AN - OPUS4-45404 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 U6 - 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 - Arinchtein, A. A1 - Schnack, R. A1 - Kraffert, K. A1 - Radnik, Jörg A1 - Dietrich, P. A1 - Sachse, René A1 - Krähnert, R. T1 - Role of Water in Phase Transformations and Crystallization of Ferrihydrite and Hematite N2 - The oxides, hydroxides, and oxo-hydroxides of iron belong to the most abundant materials on earth. They also feature a wide range of practical applications. In many environments, they can undergo facile phase transformations and crystallization processes. Water appears to play a critical role in many of these processes. Despite numerous attempts, the role of water has not been fully revealed yet. We present a new approach to study the influence of water in the crystallization and phase transformations of iron oxides. The approach employs model-type iron oxide films that comprise a defined homogeneous nanostructure. The films are exposed to air containing different amounts of water reaching up to pressures of 10 bar. Ex situ analysis via scanning electron microscopy, Transmission electron microscopy, selected area electron diffraction, and X-ray diffraction is combined with operando near-ambient pressure X-ray photoelectron spectroscopy to follow water-induced changes in hematite nd ferrihydrite. Water proves to be critical for the nucleation of ematite domains in ferrihydrite, the resulting crystallite orientation, and the underlying crystallization mechanism. KW - Iron oxide KW - Ferrihydrite KW - Hematite KW - Water KW - NAP-XPS KW - High pressure PY - 2020 U6 - https://doi.org/10.1021/acsami.0c05253 VL - 12 SP - 38714 EP - 38722 PB - ACS Publication AN - OPUS4-51201 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kjaervik, Marit A1 - Schwibbert, Karin A1 - Dietrich, P.M. A1 - Unger, Wolfgang T1 - NAP-XPS spectra of the bacterial cell-envelope of Pseudomonas fluorescens bacteria N2 - Pseudomonas fluorescens (Gram-negative) bacteria purchased from Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures were analyzed using high-resolution x-ray photoelectron spectroscopy at near ambient pressure conditions (NAP-XPS), 1500 Pa water vapor atmosphere. Fresh layers of P. fluorescence bacteria were grown on Luria Broth agar plates. Bacteria were taken from the agar plate with a sterile spatula and gently spread on a Si-wafer piece for NAP-XPS analysis. The NAP-XPS spectra of the bacterial envelope of P. fluorescence were obtained using monochromatic Al Kα radiation and include a survey scan and high-resolution spectra of C 1s, N 1s, P 2p, and O 1s as well. The presentation of the C 1s high-resolution spectrum includes the results of peak fitting analysis. KW - Pseudomonas fluorescens KW - Cell-envelope KW - Water atmosphere KW - Near ambient x-ray photoelectron spectroscopy KW - NAP-XPS PY - 2022 U6 - https://doi.org/10.1116/6.0001543 SN - 1055-5269 VL - 29 IS - 1 SP - 014008-1 PB - AVS AN - OPUS4-54464 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 U6 - 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, P.-L. A1 - Unger, Wolfgang A1 - Dietrich, Paul A1 - Holländer, A. T1 - Innovative and established strategies for the surface analysis of nitrogen and oxygen-rich plasma polymer films by XPS: an introductory guide N2 - Nitrogen- and oxygen-based plasma polymer films are materials with a complex and partially elusive surface chemistry. We present an overview of innovative and established X-ray photoelectron spectroscopy (XPS)-based analysis strategies developed to elucidate the surface chemistry of such films. We focus on both experimental methods and data analysis strategies and include the following topics: high-resolution spectra curve fitting, aging, chemical derivatization, and depth profiling by angle- and energy-resolved XPS. KW - Chemical derivatization KW - Functional groups KW - Plasma polymerization KW - X-ray photoelectron spectroscopy PY - 2015 U6 - https://doi.org/10.1002/ppap.201500115 SN - 1612-8850 SN - 1612-8869 VL - 12 IS - 9 SP - 953 EP - 967 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-35114 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietrich, P. M. A1 - Kjærvik, Marit A1 - Willneff, E. A. A1 - Unger, Wolfgang T1 - In-depth analysis of iodine in artificial biofilm model layers by variable excitation energy XPS and argon gas cluster ion sputtering XPS N2 - Here, we present a study on agarose thin-film samples that represent a model system for the exopolysaccharide matrix of biofilms. Povidone-iodide (PVP-I) was selected as an antibacterial agent to evaluate our x-ray photoelectron spectroscopy (XPS)-based methodology to trace specific marker elements, here iodine, commonly found in organic matrices of antibiotics. The in-depth distribution of iodine was determined by XPS analyses with variable excitation energies and in combination with argon gas cluster ion beam sputter cycles. On mixed agarose/PVP-I nanometer-thin films, both methods were found to solve the analytical task and deliver independently comparable results. In the mixed agarose/PVP-I thin film, we found the outermost surface layer depleted in iodine, whereas the iodine is homogeneously distributed in the depth region between this outermost surface layer and the interface between the thin film and the substrate. Depletion of iodine from the uppermost surface in the thin-film samples is assumed to be caused by ultrahigh vacuum exposure resulting in a loss of molecular iodine (I2) as reported earlier for other iodine-doped polymers. KW - Biofilm KW - XPS KW - Argon gas cluster ion sputtering KW - Variable excitation KW - Iodine PY - 2022 U6 - https://doi.org/10.1116/6.0001812 SN - 1934-8630 VL - 17 IS - 3 SP - 1 EP - 8 PB - AVS AN - OPUS4-54973 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -