TY - JOUR A1 - Zhang, Zhiyang A1 - Merk, V. A1 - Müller, Anja A1 - Unger, Wolfgang A1 - Kneipp, Janina T1 - Role of metal cations in plasmon-catalyzed oxidation: A case study of p-aminothiophenol dimerization N2 - The mechanism of the plasmon-catalyzed reaction of p-aminothiophenol (PATP) to 4,4′-dimercaptoazobenzene (DMAB) on the surface of metal nanoparticles has been discussed using data from surface-enhanced Raman scattering of DMAB. Oxides and hydroxides formed in a plasmon-catalyzed process were proposed to play a central role in the reaction. Here, we report DMAB formation on gold nanoparticles occurring in the presence of the metal cations Ag+, Au3+, Pt4+, and Hg2+. The experiments were carried out under conditions where formation of gold oxide or hydroxide from the nanoparticles can be excluded and at high pH where the formation of the corresponding oxidic species from the metal ions is favored. On the basis of our results, we conclude that, under these conditions, the selective oxidation of PATP to DMAB takes place via formation of a metal oxide from the ionic species in a plasmon-catalyzed process. By evidencing the necessity of the presence of the metal cations, the reported results underpin the importance of metal oxides in the reaction. KW - Metal ions KW - Plasmonic catalysis KW - p-aminothiophenol KW - 4,4'-dimercaptoazobenzene KW - Surface-enhanced Raman scattering PY - 2017 UR - http://pubs.acs.org/doi/abs/10.1021/acscatal.7b02700 DO - https://doi.org/10.1021/acscatal.7b02700 SN - 2155-5435 N1 - Geburtsname von Müller, Anja: Hermanns, A. - Birth name of Müller, Anja: Hermanns, A. VL - 7 IS - 11 SP - 7803 EP - 7809 PB - American Chemical Society CY - Washington AN - OPUS4-43001 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kjaervik, Marit A1 - Müller, Anja A1 - Dietrich, P. A1 - Thissen, A. A1 - Bahr, S. A1 - Ritter, B. A1 - Kemnitz, E. A1 - Unger, Wolfgang T1 - Detection of suspended nanoparticles with near-ambient pressure x-ray photoelectron spectroscopy N2 - Two systems of suspended nanoparticles have been studied with near-ambient pressure x-ray photoelectron spectroscopy: silver nanoparticles in water and strontium fluoride—calcium fluoride core-shell nanoparticles in ethylene glycol. The corresponding dry samples were measured under ultra high vacuum for comparison. The results obtained under near-ambient pressure were overall comparable to those obtained under ultra high vacuum, although measuring silver nanoparticles in water requires a high pass energy and a long acquisition time. A shift towards higher binding energies was found for the silver nanoparticles in aqueous Suspension compared to the corresponding dry sample, which can be assigned to a change of surface potential at the water-nanoparticle interface. The shell-thickness of the core-shell nanoparticles was estimated based on simulated spectra from the National Institute of Standards and Technology database for simulation of electron spectra for surface analysis. With the instrumental set-up presented in this paper, nanoparticle suspensions in a suitable Container can be directly inserted into the analysis chamber and measured without prior sample preparation. KW - Nanoparticles KW - Suspensions KW - Core-shell nanoparticles KW - NAP-XPS PY - 2017 DO - https://doi.org/10.1088/1361-648X/aa8b9d SN - 1361-648X SN - 0953-8984 N1 - Geburtsname von Müller, Anja: Hermanns, A. - Birth name of Müller, Anja: Hermanns, A. VL - 29 IS - 47 SP - 474002, 1 EP - 474002, 9 PB - IOP Publishing CY - UK AN - OPUS4-42951 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Wolfgang A1 - Senoner, Mathias A1 - Wirth, Thomas A1 - Bütefisch, S. A1 - Busch, I. T1 - Lateral resolution delivered by imaging surface-analytical instruments as SIMS, AES and XPS: Application of the BAM-L200 Certified Reference Material and related ISO Standards N2 - The certified reference material BAM-L200, a nanoscale stripe pattern for length calibration and specification of lateral resolution, is described. BAM-L200 is prepared from a cross-sectioned epitaxially grown layer stack of AlxGa1-xAs and InxGa1 xAs on a GaAs substrate. The surface of BAM-L200 provides a flat pattern with stripe widths ranging down to 1 nm. Calibration distances, grating periods and stripe widths have been certified by TEM with traceability to the length unit. The combination of gratings, isolated narrow stripes and sharp edges of wide stripes offers a plenty of options for the determination of lateral resolution, sharpness and calibration of length scale at selected settings of imaging surface analytical instruments. The feasibility of the reference material for an analysis of the lateral resolution is demonstrated in detail by evaluation of ToF-SIMS, AES and EDX images. Other applications developed in the community are summarized, too. BAM-L200 fully supports the implementation of the revised International Standard ISO 18516 (in preparation) which is based on knowledge outlined in the Technical Report ISO/TR 19319:2013. KW - Standardization KW - AES KW - XPS KW - SIMS KW - Lateral resolution KW - Certified reference material PY - 2017 SN - 1341-1756 VL - 24 IS - 2 SP - 123 EP - 128 AN - OPUS4-43138 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Wolfgang T1 - Designing a sustainable European centre for risk management and safe innovation in nanomaterials & nanotechnologies (EC4SafeNano) N2 - A central challenge to ensure the sustainable production and use of nanotechnologies is to understand the risks for environment, health and safety associated with this technology and resulting materials and products, and to identify and implement practical strategies to minimize these risks. Knowledge about nanotechnology-enabled processes and products and related environment, health and safety issues is growing rapidly, achieved through numerous European or national R&D programs over the last decade, but effective use of this knowledge for risk management by market actors is lagging behind. The EC4SafeNano initiative (www.EC4SafeNano.eu) is an ongoing effort to build a European Centre for Risk Management and Safe Innovation in Nanomaterials and Nanotechnologies. EC4SafeNano aims to bridge the gap between scientific knowledge on hazard and risk, and ‘fit-for-purpose’ risk management tools and strategies supported by measurement and control methods. The consortium comprises 15 partners (INERIS (coordinator), EU-VRi, TNO, BAM, FIOH, VITO, SP, DEMOKRITOS, TECNALIA, Health and Safety Executive, NRCWE, Paris Lodron University Salzburg, Université Libre de Bruxelles, University of Birmingham and ENEA) from 11 European Member States with significant expertise on risk assessment and management, who already provide knowledge and technical services to public and private organizations, to industry and to public authorities and regulatory bodies. The overall objective of the EC4SafeNano project is to develop a distributed Centre of European Organisations offering services for Risk Management and Safe Innovation for Nanomaterials & Nanotechnologies. The Centre will be structured as a hub-based network of organizations managed by a core group of public-oriented bodies providing risk management and safe innovation support to all stakeholders. It will be operated with the support of Associated Partners so as to expand its capabilities, resources and services. It will interact with existing platforms and centres of excellence in nanosafety and foster the organization or development of national hubs mirroring the European hub. The Centre will seek financial support from stakeholders and service users to sustain the services in the longer term. The operational objectives of the project involve understanding and mapping the needs of the various stakeholders (private and public). It will identify the resources and capabilities and develop a range of harmonized services required to meet these needs. The construction of the centre will include putting in place and implementing processes to deliver and update services, to test and benchmark services, to evaluate the governance of the Centre, and developing a business plan to ensure self-sufficiency of the Centre beyond the project lifetime. A cornerstone of the project is to build a community for risk management and safe innovation for nanotechnology. Interested persons or organisations are invited to join this initiative as registered stakeholders or Associated Partners, to engage in focus networks and to help shape the future Centre. The poster will present the EC4SafeNano initiative and will detail the role of registered stakeholders and Associated Partners. T2 - UBA Scientific Stakeholder Meeting on Nanomaterials in the Environment CY - Dessau, Germany DA - 10.10.2017 KW - Risk management KW - Nanomaterials KW - Nanotechnologies PY - 2017 AN - OPUS4-42788 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grötzsch, D. A1 - Streeck, C. A1 - Nietzold, Carolin A1 - Malzer, W. A1 - Mantouvalou, I. A1 - Nutsch, A. A1 - Dietrich, Paul A1 - Unger, Wolfgang A1 - Beckhoff, B. A1 - Kanngießer, B. T1 - A sealable ultrathin window sample cell for the study of liquids by means of soft X-ray spectroscopy N2 - A new sample cell concept for the analysis of liquids or solid-liquid interfaces using soft X-ray spectroscopy is presented, which enables the complete sealing of the cell as well as the Transport into vacuum via, for example, a load-lock system. The cell uses pressure monitoring and active as well as passive pressure regulation systems, thereby facilitating the full control over the pressure during filling, sealing, evacuation, and measurement. The cell design and sample preparation as well as the crucial sealing procedure are explained in detail. As a first proof-of-principle experiment, successful nitrogen K-edge fluorescence yield near-edge X-ray absorption fine structure experiments of a biomolecular solution are presented. For this purpose, it is shown that the careful evaluation of all involved parameters, such as window type or photon flux, is desirable for optimizing the experimental result. KW - X-ray spectroscopy KW - Analysis of liquids KW - Wet cell KW - Concanavalin A KW - NEXAFS PY - 2017 DO - https://doi.org/10.1063/1.5006122 SN - 0034-6748 SN - 1089-7623 VL - 88 IS - 12 SP - 123112-1 EP - 123112-7 PB - American Institute of Physics AN - OPUS4-43611 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 - 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 - CONF A1 - Unger, Wolfgang T1 - Metrology for spatially resolved chemical analysis at the micro and nanometre scales - Surface analysis working group (SAWG) - Report for 15th meeting (2016/17) N2 - CCQM has established a framework of comparisons to demonstrate the international comparability of chemical measurements. The key point is the establishment of comparable measurements, with traceability to internationally or nationally stated references. Originally initiated by Dr Martin P Seah, NPL, the Surface Analysis Working Group (SAWG) has been formally founded in 2003. The following terms of reference were presented to CCQM in April 2002. CCQM ratified the group as a full working group of CCQM in April 2003 with these terms of reference: - to develop pilot studies and carry out key comparisons of national measurement standards for surface and micro/nano-analysis; - to assist in identifying and establishing inter-laboratory work to improve the traceability of surface and micro/nano-analysis; - to establish and update a work plan to be adopted by CCQM; - to discuss and review the scope of the working group and to liase with other working groups related to nanotechnology. Following the 2016 meeting, the Key Comparison K-129 "Measurement of atomic fractions in Cu(In,Ga)Se2 Films" lead by KRISS and the Key Comparison K-136 on "BET specific surface area of nanoporous Al2O3" lead by UNIIM&BAM have been finished in 2016. The 15th meeting of SAWG will focus on - survey on CMC claim submitted with reference to K-129 and K-136. - the overall and SAWG specific aspects of the CCQM Strategy process, - a joint meeting with the Inorganic Working Group addressing number concentrations of nano particles, - discussion of future comparisons. T2 - CCQM Plenary Meeting at BIPM 2017 CY - Paris, France DA - 27.4.17 KW - Metrology KW - Comparisons KW - CCQM PY - 2017 AN - OPUS4-40277 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Dietrich, P. A1 - Thissen, A. A1 - Kulak, N. A1 - Kjaervik, Marit A1 - Unger, Wolfgang T1 - XPS surface chemical analysis of aqueous solutions with EnviroESCA N2 - Water and aqueous reagents are essential in any biological process or system. But apart from a few special low vapor-pressure cases, liquids have not been accessible to any technique requiring UHV conditions. EnviroESCA opens up this exciting field of applications. In this paper first results from water based samples are presented as a proof of concept to demonstrate the special capabilities of EnviroESCA analyzing liquid samples. The following solutions were investigated under near ambient pressure conditions: i.) water, ii.) brine, iii.) an oil in water dispersion, iv.) aqueous iron(II) sulfate heptahydrate, and v.) a suspension of nano silver particles in water. KW - Surface Analysis KW - Near Ambient Pressure XPS KW - Aqueous Solutions PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-394603 UR - http://www.enviro.specs.de/cms/upload/bilder/EnviroESCA/Applications/Liquids/Application-Note_EnviroESCA_Aqueous_Solutions.pdf N1 - BAM Mitarbeiter Beitrag im Acknowledgement definiert. IS - #000394 SP - 1 PB - SPECS CY - Berlin AN - OPUS4-39460 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Passiu, Cristiana A1 - Rossi, Antonella A1 - Bernard, Laetitia A1 - Paul, Dennis A1 - Hammond, John A1 - Unger, Wolfgang A1 - Venkataraman, Nagaiyanallur V. A1 - Spencer, Nicholas D. T1 - Fabrication and Microscopic and Spectroscopic Characterization of Planar, Bimetallic, Micro- and Nanopatterned Surfaces N2 - Micropatterns and nanopatterns of gold embedded in silver and titanium embedded in gold have been prepared by combining either photolithography or electron-beam lithography with a glue-free template-stripping procedure. The obtained patterned surfaces have been topographically characterized using atomic force microscopy and scanning electron microscopy, showing a very low root-mean-square roughness (<0.5 nm), high coplanarity between the two metals (maximum height difference ≈ 2 nm), and topographical continuity at the bimetallic interface. Spectroscopic characterization using X-ray photoelectron spectroscopy (XPS), time-of-flight secondary-ion mass spectrometry (ToF-SIMS), and Auger electron spectroscopy (AES) has shown a sharp chemical contrast between the two metals at the interface for titanium patterns embedded in gold, whereas diffusion of silver into gold was observed for gold patterns embedded in silver. Surface flatness combined with a high chemical contrast makes the obtained surfaces suitable for applications involving functionalization with molecules by orthogonal adsorption chemistries or for instrumental calibration. The latter possibility has been tested by determining the image sharpness and the analyzed area on circular patterns of different sizes for each of the spectroscopic techniques applied for characterization.This is the first study in which the analyzed area has been determined using XPS and AES on a flat surface, and the first example of a method for determining the analyzed area using ToF-SIMS. KW - XPS KW - AES KW - SIMS KW - Lateral resolution KW - Test pattern PY - 2017 UR - http://pubs.acs.org/doi/abs/10.1021/acs.langmuir.7b00942 DO - https://doi.org/10.1021/acs.langmuir.7b00942 SN - 0743-7463 VL - 33 IS - 23 SP - 5657 EP - 5665 PB - ACS AN - OPUS4-40929 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -