TY - CONF A1 - Thünemann, Andreas T1 - A look inside nanoparticles N2 - Small-angle scattering is the method of choice when it comes to obtaining information about the interior of nanoparticles. The aim is to make nanotechnology safer. While the use of small-angle neutron scattering (SANS) is limited to a few instruments in the world, small-angle X-ray scattering (SAXS) is widely accessible, with an upward trend. The example of core-shell particles shows how simple their analysis is with data from an Anton Paar laboratory system. Here, SAXS is a central tool for the development of new reference materials based on poly(methyl) acrylate-PVDF core-shell particles. The dimensions of the cores and shells can be precisely determined. A detailed analysis makes it possible to show that the cores contain fluorinated and nonfluorinated polymers, whereas the shell consist only of PVDF. This core-shell particles with a diameter around 40 nm show a significantly higher PVDF beta phase content than the PVDF homopolymer when using an emulsion polymerization technique. This finding is of importance with respect to applications in electroactive devices. T2 - SAXS excites: International SAXS Symposium 2019 CY - Graz, Austria DA - 24.09.2019 KW - Small-angle X-ray scattering KW - SAXS KW - Nanoplastics PY - 2019 AN - OPUS4-49126 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hodoroaba, Vasile-Dan A1 - Mansfeld, Ulrich A1 - Pellegrino, F. A1 - Maurino, V. A1 - Marguet, S. A1 - Testard, F. A1 - Tache, O. A1 - Bartzcak, D. T1 - New reference material candidates for traceable size measurement of nonspherical nanoparticles N2 - Size measurement of nanoparticles (NP) becomes a challenging analytical problem when non-spherical shapes must be traceably measured. However, most industrial NPs have irregular shapes and broad size distribution making it often more complex to follow European regulatory to identify a material as a nanomaterial according to which accurate measurement of the smallest dimension and its size Distribution is necessary. The European research project nPSize - Improved traceability chain of nanoparticle size measurements aims to fill this gap by developing potential non-spherical reference nanoparticles, measurement procedures and physical modelling to improve the traceability chain, comparability and compatibility for NP size measurements between different methods. Therefore, new model NP with well-controlled shape has been synthesized and are supposed to be systematically characterized using the traceable methods scanning/transmission electron microscopy, atomic force microscopy and small angle X-ray scattering. Following NP candidates are under investigation with respect to their homogeneity and stability: (i) titania nanoplatelets (10-15 nm thickness x 50-100 nm lateral), (ii) titania bipyramides (~60 nm length x 40 nm width), (iii) titania acicular particles (100 nm length x 15-20 nm width; aspect ratio 5.5/6), (iv) gold nanorods (~10 nm width x 30 nm length), and (v) gold nanocubes (~55 nm x 55 nm x 55 nm). In addition, sample preparation procedures as well as measurement analysis procedures with evaluation of appropriate measurands and descriptors for each material class and method are being developed to support standardization. To underpin the traceability of the size measurement of nonspherical NP, physical modelling of the signals in e.g. electron microscopy techniques will be used and in combination, the implementation of machine learning is aimed to facilitate measurement Analysis procedures, especially regarding the accurate thresholding/segmentation of the NPs. T2 - European Conference on Applications of Surface and Interface Analysis ECASIA 2019 CY - Dresden, Germany DA - 15.09.2019 KW - Nanoparticles KW - Size distribution KW - Electron microscopy KW - Certified reference materials KW - Traceability PY - 2019 AN - OPUS4-49227 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bresch, Harald A1 - Rühle, Bastian A1 - Hodoroaba, Vasile-Dan A1 - Seeger, Stefan A1 - Resch-Genger, Ute A1 - Braun, Ulrike A1 - Jann, Oliver A1 - Wilke, Olaf A1 - Geißler, Daniel A1 - Schmidt, Alexandra A1 - Unger, Wolfgang A1 - Sturm, Heinz T1 - Stand der Aktivitäten zur gemeinsamen Forschungsstrategie N2 - Die gemeinsame Forschungsstrategie der Bundesoberbehörden zur Nanotechnologie wurde 2016 veröffentlicht. Die darin enthaltenen Aufgaben wurden von den Bundesoberbehörden vielfältig bearbeitet. Diese Präsentation gibt einen Überblick über die Projekte, die von der BAM bis 2019 bearbeitet wurden/werden und sich in den Rahmen der Forschungsstrategie einordnen. T2 - Workshop zur gemeinsamen Forschungsstrategie der Bundesoberbehörden „Nanomaterialien und andere innovative Werkstoffe: anwendungssicher und umweltverträglich“ CY - Berlin, Germany DA - 02.09.2019 KW - Nano KW - Bundesoberbehörden KW - Forschungsstrategie KW - Nanomaterialien KW - Nanotechnologie PY - 2019 AN - OPUS4-49586 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wegner, Karl David A1 - Carrière, M. A1 - Reiss, P. T1 - Tuning the photoluminescence of inp quantum dots with gallium N2 - Semiconductor nanocrystals (quantum dots, QDs) are well known for their superior photophysical properties and enabled advancements in several key technologies of the 21st century and numerous technological applications. However, the most studied II-VI semiconductor nanocrystals contain the toxic heavy metal element cadmium, which is limiting their utilization in commercial applications. This has drawn the interest to alternative materials with less toxicity but having similar photophysical features. The newest generation of TV screens based on QDs have shown that there is a promising environmentally friendly alternative with similar optoelectronic properties, namely indium phosphide (InP) QDs. InP QDs possess a bulk band gap of 1.35 eV with an exciton Bohr radius of ca. 10 nm and thus allow to tune their photoluminescence (PL) from the visible to the near-infrared. Tuning the size and shape of InP QDs and thus tailor their optoelectronic properties can be achieved by different strategies, which range from different types and concentrations of precursors, synthesis temperature or post-synthetic manipulations like etching. The incorporation of other elements like Gallium within the InP core synthesis is another possibility. Using a GaP intermediate layer before growing a ZnS shell has been shown to increase the PL quantum yield, which has been attributed to reduced lattice strain and the removal of phosphor vacancies. Different Ga precursors were investigated but a thorough investigation in terms of their reactivity, localization in the QD and influence on the photophysical properties is lacking to date. In this contribution we will present the detailed investigation of the presence of two different Ga precursors within the InP core synthesis. Photophysical characterizations (steady-state and PL life-time measurements), transmission electron microscopy, XRD and EDX gave insights into the reactivity of the Ga precursors, the Ga localization in the InP core and influences on the photophysical properties. The variation of the precursor and surfactant concentration and the utilization of different ligands for the Ga precursor allowed tuning the PL emission towards the blue or the red. Depending on the used precursor type we observed the formation of larger-sized InP/GaP core/shell nanocrystals or the formation of InGaP alloy structures enabling to assess the blue range of emission (475 nm). T2 - Zsigmondy Colloquium CY - Dresden, Germany DA - 10.07.2019 KW - Indium phosphide KW - Quantum dots KW - Gallium doping PY - 2019 AN - OPUS4-49426 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wegner, Karl David A1 - Weigert, Florian A1 - Häusler, I. A1 - Carrière, M. A1 - Reiss, P. A1 - Resch-Genger, Ute T1 - Influence of the ZnSe thickness on the photophysical properties of large-size InP/ZnSe/ZnS core-shell QDs N2 - Semiconductor nanocrystals (quantum dots, QDs) are well known for their superior optoelectronic properties and enabled advancements in several key technologies of the 21st century. II-VI QDs containing the heavy metal element cadmium plaid a central role in this research area. Due to the concerns regarding their toxic potential, the European Union will ban cadmium in 2020 from use in any consumer product. Due to their comparable optoelectronic properties and a more environmentally friendly character, indium phosphide based QDs (InP-QDs) are a promising alternative. Their large application potential was already shown in their utilization in the newest commercial TV screens. A vital role for highly luminescent QDs for such an application plays the growth of a surface passivating shell around the InP core. The combination of InP/ZnSe/ZnS in so-called core/shell/shell materials exploits the advantages of a small lattice mismatch (3.3%) between InP and ZnSe and the large band gap of ZnS to efficiently confine the excitons in the core and to increase the overall chemical stability. Using a thin ZnSe layer and a thick ZnS shell has shown to improve the optical properties of InP QDs and only recently, the prevention of blinking and mono-exponential decay kinetics could be achieved with a thick ZnSe Shell. In our contribution, we investigated the influence of the thickness of the intermediate ZnSe layer (1 to 8 monolayers (ML)) on the photophysical properties of InP/ZnSe/ZnS core/shell/shell QDs with a final size of about 10 nm on the ensemble and the single-particle level. By rendering these InP QDs water-soluble, we were able to compare their properties in the organic and aqueous phase and further studied their toxicological potential depending on the chemical composition of their surface shell. T2 - Nanoscience with nanocrystals (NaNaX) 9 CY - Hamburg, Germany DA - 16.09.2019 KW - Indium phosphide KW - Quantum dots KW - Core-shell structures KW - Single-particle measurements PY - 2019 AN - OPUS4-49427 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute T1 - A journey in science from a graduate student in physical chemistry to head of division biophotonics N2 - I will provide a personal overview of the most important steps of my career in science, a journey from a graduate student in physical chemistry in an environment dominated by male-scientists over a postdoc with a female professor in the US to the leader of a research group, head of division Biophotonics at BAM. This will include my choices of research topics, how I learnt to write well cited publications, even on topics such as reference materials and quality assurance,1-4 and eventually started to give lectures at Free University Berlin granting me the right to act as first supervisor of undergraduate and graduate students. T2 - Women in Science CY - Erlangen, Germany DA - 22.07.2024 KW - Lanthanide KW - Nanoparticle KW - Silica KW - Quantum dot KW - Polymer KW - Surface group KW - Luminescence KW - Quantitative spectroscopy KW - Quantum yield KW - Lifetime KW - Quality assurance KW - Synthesis KW - Surface modification KW - Photophysics PY - 2024 AN - OPUS4-60724 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Resch-Genger, Ute A1 - Tavernaro, Isabella A1 - Abram, Sarah-Luise A1 - Andresen, Elina A1 - Matiushkina, Anna T1 - Quantifying the number of total and accessible functional groups on nanomaterials N2 - Inorganic and organic functional nanomaterials (NM) of different size, shape, chemical composition, and surface chemistry are relevant for many key technologies of the 21st century. Decisive for most applications of NM are their specific surface properties, which are largely controlled by the chemical nature and number of ligands and functional groups (FG on the NM surface. The surface chemistry can strongly affect the physicochemical properties of NM, their charge, hydrophilicity/hydrophobicity, reactivity, stability, and processability and thereby their impact on the environment and biological species as well as their possible risk for human health. Thus, reliable, validated, and eventually standardized analytical methods for the characterization of NM surface chemistry, i.e., the chemical identification, quantification, and accessibility of FG and surface ligands 1,2] flanked by interlaboratory comparisons, control samples, and reference materials, 2 ,3 are of considerable importance for process and quality control of NM production and function. This is also important for the safe use of NM the design of novel NM, and sustainable concepts for NM fabrication. Here, we provide an overview of analytical methods for FG analysis and quantification and highlight method and material related challenges for selected NM. Analytical techniques address ed include electrochemical titration methods, optical assays, nuclear magnetic resonance (NMR) and vibrational (IR) spectroscopy, and X ray based and thermal analysis methods. Criteria for method classification and evaluation include the need for a signal generating label, provision of either the total or derivatizable number of FG, and suitability for process and production control. T2 - AUC - Analytical Ultracentrifugation CY - Nuremberg, Germany DA - 22.07.2024 KW - Nanoparticle KW - Particle KW - Microparticle KW - Silica KW - Quantum dot KW - Polymer KW - Surface group KW - Luminescence KW - Quality assurance KW - Synthesis KW - Surface modification KW - ILC KW - Optical assay KW - Functional group KW - Ligand KW - qNMR KW - Conductometry KW - Potentiometry KW - Standardization KW - Reference product KW - Reference material PY - 2024 AN - OPUS4-60749 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mrkwitschka, Paul A1 - Abram, Sarah-Luise A1 - Rühle, Bastian A1 - Hodoroaba, Vasile-Dan T1 - Correlative analysis with electron microscopy applied in different operating modes (SEM, STEM-in-SEM and TEM) for the accurate morphological characterisation of non-spherical fine nanoparticles N2 - Electron microscopy applied in different operating modes, e.g., SEM, TEM or STEM-in-SEM, is the gold standard method to investigate the exact size and shape of individual nanoparticles. However, when fine nanoparticles with a non-monodisperse size distribution and non-spherical shapes are analysed, achieving an accurate result is challenging. Deviations in size measurements of more than 10% may occur. Understanding of the contrasts and sensitivities characteristic to the individual operating modes of an electron microscope is key in interpreting and evaluating quantitatively the measurement uncertainties needed for an eventual certification of specific nanoparticles via traceable results. Further, beyond the pure measurement, the other components in the analysis workflow with significant impact on the overall measurement uncertainties are the sample preparation and the image segmentation. In the present study the same areas of selected iron oxide fine nanoparticles (<25 nm) as reference nanomaterial (candidate) prepared on substrate for electron microscopy imaging are analysed correlatively with SEM, STEM-in-SEM and TEM with respect to their size and shape distribution. Individual significant measurement uncertainties are discussed, e.g., the sensitivity of secondary electron detectors of InLens-type to the surface morphology, particularly to the presence of an ultrathin organic coating or signal saturation effects on the particle edges, to electron beam exposure, to surface contamination, or the selection of the threshold for image segmentation. Another goal of this study is to establish a basis of analysis conditions which shall guarantee accurate results when both manual and particularly (semi-)automated segmentation approaches are applied. Advantages as well as limitations of the use of different electron microscopy operating modes, applied individually and correlatively, are highlighted. T2 - E-MRS 2024 Spring Meeting CY - Strasbourg, France DA - 27.05.2024 KW - Nanoparticles KW - Electron Microscopy KW - Metrology KW - Imaging KW - Reference materials PY - 2024 AN - OPUS4-60436 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hodoroaba, Vasile-Dan T1 - Measurement of Lateral Dimensions of Particles & Flakes (2D) by Imaging Methods N2 - An overview with the basics of size and shape measurement of particles and 2D structures according to established methodologies (and popular imaging processing software packages) with imaging techniques is given. Main descriptors are explained based on practical cases are determined interactively at the flipchart. T2 - MaterialsWeek 2024 CY - Limassol, Cyprus DA - 17.06.2024 KW - Nanoparticles KW - 2D materials KW - Lateral dimensions KW - ISO KW - Imaging PY - 2024 AN - OPUS4-60454 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wegner, Karl David A1 - Walter, J. A1 - Stiegler, L. M. S. A1 - Weigert, F. A1 - Peukert, W. A1 - Resch-Genger, Ute T1 - Size-resolved emission properties of core/shell CdSe/CdS quantum dots via multiwavelength emission analytical ultracentrifugation N2 - Colloids provide manifold opportunities for targeted product design due to their tunable properties with respect to size, shape, composition, surface, and spectral characteristics. However, the determination of structure-property relationships is quite challenging as most particulate samples exhibit polydispersity of their disperse properties. Analytical ultracentrifugation (AUC) is a fractionating technique and highly accurate method for the multidimensional analysis of nanoparticles as it permits the differentiation of spectral information linked to hydro- and thermodynamic properties of the particles. So far, characterization capabilities for fluorescent nanoparticles by AUC were limited, as the formerly commercially available fluorescence detector could not provide any spectral information. Using a multiwavelength emission detector developed in our group, it is possible to extract spectra of fluorescent particles and biomolecules alongside their sedimentation and diffusion coefficients within a single centrifugation experiment. In our contribution, we will highlight that even narrowly distributed core/shell CdSe/CdS quantum dots still show size- and structure-dependent shifts of their fluorescence spectra, which can be resolved with our AUC system in an ensemble measurement. Thereby, we can link spectral changes of only a few nanometers to particle sizes retrieved with Angstrom size resolution. Single-particle measurements not only supported the results obtained with the AUC system but also provided deeper insights into the photophysical processes of individual QDs, clearly demonstrating the complementary nature of the techniques used. With our novel multiwavelength emission detector and the established extinction-based detector for AUC, a comprehensive platform for the holistic characterization of fluorescent colloids is now available. T2 - 26th International Analytical Ultracentrifugation Symposium CY - Bad Staffelstein, Germany DA - 24.07.2024 KW - Quantum dots KW - Analytical ultracentrifugation KW - Reference materials KW - Calibrated fluorescence measurements KW - Size-resolved emission PY - 2024 AN - OPUS4-60814 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -