TY - JOUR A1 - Sarhan, R. M. A1 - Koopman, W. A1 - Schuetz, R. A1 - Schmid, Thomas A1 - Liebig, F. A1 - Koetz, J. A1 - Bargheer, M. T1 - The importance of plasmonic heating for the plasmondriven photodimerization of 4-nitrothiophenol N2 - Metal nanoparticles form potent nanoreactors, driven by the optical generation of energetic electrons and nanoscale heat. The relative influence of these two factors on nanoscale chemistry is strongly debated. This article discusses the temperature dependence of the dimerization of 4-nitrothiophenol (4-NTP) into 4,4′-dimercaptoazobenzene (DMAB) adsorbed on gold nanoflowers by Surface-Enhanced Raman Scattering (SERS). Raman thermometry shows a significant optical heating of the particles. The ratio of the Stokes and the anti-Stokes Raman signal moreover demonstrates that the molecular temperature during the reaction rises beyond the average crystal lattice temperature of the plasmonic particles. The product bands have an even higher temperature than reactant bands, which suggests that the reaction proceeds preferentially at thermal hot spots. In addition, kinetic measurements of the reaction during external heating of the reaction environment yield a considerable rise of the reaction rate with temperature. Despite this significant heating effects, a comparison of SERS spectra recorded after heating the sample by an external heater to spectra recorded after prolonged illumination shows that the reaction is strictly photo-driven. While in both cases the temperature increase is comparable, the dimerization occurs only in the presence of light. Intensity dependent measurements at fixed temperatures confirm this finding. KW - Nanoparticles KW - Plasmonic heating KW - Raman spectroscopy PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-475140 DO - https://doi.org/10.1038/s41598-019-38627-2 SN - 2045-2322 VL - 9 IS - 1 SP - 3060, 1 EP - 8 PB - Nature Publishing Group AN - OPUS4-47514 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wäsche, Rolf A1 - Sato, K. A1 - Brandt, Guido A1 - Schmid, Thomas A1 - Sasaki, S. A1 - Woydt, Mathias T1 - Wear behaviour of MgO stabilized zirconia in hot steam environment up to 400°C N2 - Self-mated magnesia stabilized zirconia (Mg-PSZ) ceramic sliding couples have been investigated at 100 N load (P0max= 1324 MPa) in oscillating sliding conditions in different humidity conditions in air and in hot steam. Temperatures have been varied up to 400 °C and pressures up to 6 bars. The results show that the wear behavior of MgO-ZrO2 under high Hertzian contact pressures is strongly dependent on temperature and is similar for both dry oscillating and oscillating in hot steam. However, although the evolution in wear rates on temperature is similar and the wear rates of MgO-ZrO2 plunged above 300 °C in hot steam and air by nearly three orders of magnitude, SEM micrographs revealed in hot steam at 400 °C smooth wear tracks. In contrast, hot steam enhanced the tribochemistry of self-mated alumina couples and reduced wear rates. Hot steam decreased the coefficients of friction of MgO-ZrO2 with increasing temperature, but not the wear rates. KW - Hot steam KW - Zirconia KW - Friction KW - Wear KW - Tribofilm KW - Raman spectroscopy PY - 2019 DO - https://doi.org/10.1016/j.wear.2019.01.047 VL - 426-427 SP - 428 EP - 432 PB - Elsevier B.V. AN - OPUS4-47873 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rühlmann, Madlen A1 - Büchele, Dominique A1 - Ostermann, Markus A1 - Bald, Ilko A1 - Schmid, Thomas T1 - Challenges in the quantification of nutrients in soils using laser-induced breakdown spectroscopy – A case study with calcium N2 - The quantification of the elemental content in soils with laser-induced breakdown spectroscopy (LIBS) is challenging because of matrix effects strongly influencing the plasma formation and LIBS signal. Furthermore, soil heterogeneity at the micrometre scale can affect the accuracy of analytical results. In this paper, the impact of univariate and multivariate data evaluation approaches on the quantification of nutrients in soil is discussed. Exemplarily, results for calcium are shown, which reflect trends also observed for other elements like magnesium, silicon and iron. For the calibration models, 16 certified reference soils were used. With univariate and multivariate approaches, the calcium mass fractions in 60 soils from different testing grounds in Germany were calculated. The latter approach consisted of a principal component analysis (PCA) of adequately pre-treated data for classification and identification of outliers, followed by partial least squares regression (PLSR) for quantification. For validation, the soils were also characterised with inductively coupled plasma optical emission spectroscopy (ICP OES) and X-ray fluorescence (XRF) analysis. Deviations between the LIBS quantification results and the reference analytical results are discussed. KW - Laser-induced breakdown spectroscopy (LIBS) KW - Soil KW - Multivariate data analysis KW - Principal component analysis (PCA) KW - Partial least squares regression (PLSR) PY - 2018 DO - https://doi.org/10.1016/j.sab.2018.05.003 VL - 146 SP - 115 EP - 121 PB - Elsevier B.V. AN - OPUS4-45070 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wäsche, Rolf A1 - Brandt, Guido A1 - Ehrke, Roman A1 - Nolze, Gert A1 - Schmid, Thomas A1 - Sasaki, S. A1 - Woydt, Mathias T1 - Wear behaviour of alpha-alumina in hot steam at high contact pressure N2 - The work examines the wear behaviour of α-aluminium oxide by combining thermodynamic modelling with advanced wear testing as well as analytical methods to get a better understanding of this structural ceramic material wear behavior and its possible use in high temperature steam environment. KW - Aluminium oxide KW - Temperature KW - Hot steam KW - Diaspore KW - Ceramic KW - Wear PY - 2018 DO - https://doi.org/10.1016/j.wear.2018.02.012 SN - 0043-1648 SN - 1873-2577 VL - 404-405 SP - 22 EP - 30 PB - Elsevier B.V. AN - OPUS4-44449 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wäsche, Rolf A1 - Jayachandran, Ashok Raj A1 - Brandt, Guido A1 - Schmid, Thomas A1 - Tamura, T. A1 - Nakase, T. T1 - Tribofilm formation of a-C:H coatings under influence of temperature in boundary lubricated oscillating sliding against alumina and silicon nitride N2 - Gegenstand dieses Beitrags ist der Einfluss von Temperatur und Gegenkörperwerkstoff auf die Bildung von Tribofilmen auf a-C:H Beschichtungen. Dies wurde mit einer Kugel-Ebene Anordnung im geschmierten Kontakt untersucht. KW - a-C:H KW - Temperature KW - Tribofilm KW - Lubricated sliding KW - Alumina KW - Silicon nitride PY - 2018 SN - 0724-3472 VL - 65 IS - 5 SP - 28 EP - 37 PB - expert Verlag CY - Tübingen AN - OPUS4-46034 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Abad Andrade, Carlos Enrique A1 - Florek, S. A1 - Becker-Ross, H. A1 - Huang, M.-D. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Lippitz, Andreas A1 - Hodoroaba, Vasile-Dan A1 - Schmid, Thomas A1 - Heinrich, Hans-Joachim A1 - Recknagel, Sebastian A1 - Jakubowski, Norbert A1 - Panne, Ulrich T1 - Zirconium permanent modifiers for graphite furnaces used in absorption spectrometry: understanding their structure and mechanism of action N2 - The mechanism of action of zirconium permanent modifiers on graphite surfaces was investigated in order to understand its influence on the analytical signal in atomic and molecular absorption spectrometry (AAS/MAS). For this, the molecule formation of CaF was studied, which is used for the indirect analytical determination of fluorine in high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS). The kinetics of this reaction was established by monitoring its molecular spectrum at different atomisation temperatures. An Arrhenius plot showed a pseudo-first order reaction with respect to fluorine (n = 1). An intermediate state was isolated, and its structure was elucidated by spectroscopic methods: scanning electron microscopy with energy dispersive X-ray spectroscopy (SEMEDX), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XANES and EXAFS), and Raman microspectroscopy. We propose here a mechanism, where ZrO2 acts as a heterogeneous catalyst: after a pyrolytic step, an intermediate state of ZrO(OCaF) is activated, and at higher temperatures, CaF(g) is released from the zirconium-coated graphite surface. No evidence of the formation of zirconium carbide was found. Consequently, as the CaF formation is catalysed by a heterogeneous catalyst, surface modifications with ZrO2 nanoparticles and ZrO xerogels were investigated in order to increase the surface area. Their influence was evaluated in the molecule formation of CaF, CaCl, CaBr, and CaI. Graphite furnace modification with zirconium oxide nanoparticles proves to be the best choice for fluorine analysis with a signal enhancement of more than eleven times with respect a non-coated graphite furnace. However, the influence of zirconium modifications in the analytical signals of Cl, and I is lower than the F signals or even negative in case of the Br. Understanding zirconium modifiers as heterogeneous catalysts offers a new perspective to AAS and MAS, and reveals the potential of surface analytical methods for development of improved permanent modifiers and graphite furnace coatings. KW - Zirconium KW - HR-CS-MAS KW - Graphite furnace KW - Nanoparticles KW - Xerogel KW - Calcium monofluoride KW - Absorption spectrometry PY - 2018 UR - https://pubs.rsc.org/en/content/articlelanding/2018/ja/c8ja00190a DO - https://doi.org/10.1039/C8JA00190A SN - 0267-9477 VL - 33 IS - 12 SP - 2034 EP - 2042 PB - Royal Society of Chemistry AN - OPUS4-46775 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dariz, P. A1 - Schmid, Thomas T1 - Ferruginous phases in 19th century lime and cement mortars: A Raman microspectroscopic study N2 - Raman microscopic imaging was just recently introduced into the analysis of residual Roman and Portland cement grains in 19th century cement stone, displaying evidence of the experimental adaptation of contemporary technological knowledge and practice to local circumstance. Beyond calcium ferrites, this study deals with ferruginous clinker phases that are atypical compared to present-day commercial conditions of manufacture, such as iron oxides, clinopyroxenes or pyroxenoids. Analog, microtexture, mineralogy and chemical composition of pulverized ferrosilicate slag used in the course of the 19th century as mineral additive in lime mortar reflect local resource utilization, recording the melting history within the furnace and the effectiveness of the reduction process of a single smelting event. In the case of the discussed example, chemical imaging by Raman microscopy allowed deducing a lime-rich, low-silica melt exposed to fairly reducing conditions because of the detection of the pyrometallurgic phases fayalite (Fe2SiO4), kirschsteinite (CaFeSiO4) and calcioolivine (Ca2SiO4) in zoned olivine laths and (with the melilite gehlenite, Ca2Al2SiO7) in the Interstitial matrix, cross-cut by dendritic wuestite (FeO). The presented analytical approach faces the high spatial complexity of such mortar samples by microspectroscopic imaging with micrometer lateral resolution and their chemical complexity by extracting the rich chemical information content from Raman spectra. Intensity maps of marker bands provide spatial phase distributions. Furthermore, maps of peak positions can give access to the dissemination of spectroscopically similar phases of solid solution series (e.g., olivine and calcium Aluminate ferrite) as well as varying amounts of incorporated foreign cations (e.g., in hematite). KW - Residual cement grains KW - Ferrite KW - Iron oxide KW - Slag KW - Olivine KW - Raman microspectroscopy PY - 2017 DO - https://doi.org/10.1016/j.matchar.2017.04.009 SN - 1044-5803 SN - 1873-4189 VL - 129 SP - 9 EP - 17 PB - Elsevier AN - OPUS4-40039 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neuhaus, Birger A1 - Schmid, Thomas A1 - Riedel, Jens T1 - Collection management and study of microscope slides: Storage, profiling, deterioration, restoration procedures, and general recommendations N2 - A wide range of aspects concerning microscope slides, their preparation, long-time storage, curatorial measures in collections, deterioration, restoration, and study is summarized based on our own data and by analyzing more than 600 references from the 19th century until 2016, 15 patents, and about 100 Materials Safety Data Sheets. Information from systematic zoology, conservation sciences, chemistry, forensic sciences, pathology, paleopathology, applied sciences like food industry, and most recent advances in digital imaging are put together in order to obtain a better understanding of which and possibly why mounting media and coverslip seals deteriorate, how slides can be salvaged, which studies may be necessary to identify a range of ideal mounting media, and how microscope studies can benefit from improvements in developmental biology and related fields. We also elaborate on confusing usage of concepts like that of maceration and of clearing. The chemical ingredients of a range of mounting media and coverslip seals are identified as much as possible from published data, but this information suffers in so far as the composition of a medium is often proprietary of the manufacturer and may vary over time. Advantages, disadvantages, and signs of deterioration are documented extensively for these media both from references and from our own observations. It turns out that many media degrade within a few years, or decades at the latest, except Canada balsam with a documented life-time of 150 years, Euparal with a documented life-time of 50 years, and glycerol-paraffin mounts sealed with Glyceel, which represents almost the only non-deteriorating and easily reversible mount. Deterioration reveals itself as a yellowing in natural resins and as cracking, crystallization, shrinkage on drying or possibly on loss of a plasticizer, detachment of the coverslip, segregation of the ingredients in synthetic polymers, as well as continued maceration of a specimen to a degree that the specimen virtually disappears. Confusingly, decay does not always appear equally within a collection of slides mounted at the same time in the same medium. The reasons for the deteriorative processes have been discussed but are controversial especially for gum-chloral media. Comparing data from conservation sciences, chemical handbooks, and documented ingredients, we discuss here how far chemical and physical deterioration probably are inherent to many media and are caused by the chemical and physical properties of their components and by chemicals dragged along from previous preparation steps like fixation, chemical maceration, and physical clearing. Some recipes even contain a macerating agent, which proceeds with its destructive work. We provide permeability data for oxygen and water vapor of several polymers contained in mounting media and coverslip seals. Calculation of the penetration rate of moisture in one example reveals that water molecules reach a specimen within a few days up to about a month; this lays to rest extensive discussions about the permanent protection of a mounted specimen by a mounting medium and a coverslip seal. Based on the ever growing evidence of the unsuitable composition and application of many, and possibly almost all, mounting media, we strongly encourage changing the perspective on microscope slides from immediate usability and convenience of preparation towards durability and reversibility, concepts taken from conservation sciences. Such a change has already been suggested by Upton (1993) more than 20 years ago for gum-chloral media, but these media are still encouraged nowadays by scientists. Without a new perspective, taxonomic biology will certainly lose a large amount of its specimen basis for its research within the next few decades. Modern non-invasive techniques like Raman spectroscopy may help to identify mounting media and coverslip seals on a given slide as well as to understand ageing of the media. An outlook is given on potential future studies. In order to improve the situation of existing collections of microscope slides, we transfer concepts as per the Smithsonian Collections Standards and Profiling System, developed for insect collections more than 25 years ago, to collections of slides. We describe historical and current properties and usage of glass slides, coverslips, labels, and adhesives under conservational aspects. In addition, we summarize and argue from published and our own experimental information about restorative procedures, including re-hydration of dried-up specimens previously mounted in a fluid medium. Alternatives to microscope slides are considered. We also extract practical suggestions from the literature concerning microscope equipment, cleaning of optical surfaces, health risks of immersion oil, and recent improvements of temporary observation media especially in connection with new developments in digital software. KW - Re-hydration KW - Mounting medium KW - Coverslip seal KW - Fixation KW - Maceration KW - Clearing KW - Immersion oil KW - Permeability PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-423322 SN - 978-1-77670-222-0 SN - 978-1-77670-223-7 DO - https://doi.org/10.11646/zootaxa.4322.1.1 SN - 1175-5326 VL - 4322 IS - 1 SP - 1 EP - 173 PB - Magnolia Press CY - Auckland, Neuseeland AN - OPUS4-42332 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dariz, P. A1 - Jakob, C. A1 - Ectors, D. A1 - Neubauer, J. A1 - Schmid, Thomas T1 - Measuring the Burning Temperatures of Anhydrite Micrograins in a High-Fired Medieval Gypsum Mortar N2 - Typical feature of high-fired medieval gypsum mortars is a compact microstructure of squat gypsum crystals containing firing products as remains of the calcination process. So far, the burning history of the binder is estimated based on morphological characteristics of the latter. A novel Raman microspectroscopy approach provides access to the calcination temperatures of individual anhydrite grains based on quantifiable spectroscopic changes appearing due to gradual variations of crystallinity, as independently confirmed by X-ray diffraction analysis of anhydrites synthesised at temperatures between 500°C and 900°C. The approach was successfully applied to the high-fired gypsum mortar of a South Tyrolean stucco sculpture of a pieta dated around 1420. Microparticles of burned anhydrite II with firing temperatures scattered around 650°C and clusters of thermally damaged natural anhydrite II crystals from the raw material were identified and imaged. KW - Analytical methods KW - Gypsum technology KW - High-fired gypsum mortar KW - Raman microspectroscopy KW - Thermal anhydrite PY - 2017 DO - https://doi.org/10.1002/slct.201701260 VL - 2 IS - 28 SP - 9153 EP - 9156 PB - Wiley VCH Verlag AN - OPUS4-42458 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmid, Thomas A1 - Schäfer, N. A1 - Abou-Ras, D. T1 - Raman microspectroscopy provides access to compositional and microstructural details of polycrystalline materials N2 - This overview article provides insight into how to apply Raman spectroscopy in combination with a confocal, optical microscope setup on polycrystalline material systems, in order to obtain quantitative information on phase distribution, grain sizes, crystal orientations and microstrain. Although the present work uses Cu(In,Ga)(S,Se)₂ absorber layers in corresponding thin-film solar cells as a model system to demonstrate the capabilities of Raman microspectroscopy, the approaches discussed may be applied to any organic or inorganic, polycrystalline materials system. KW - Raman microscopy KW - Microstructure KW - Microspectroscopic imaging KW - Polycrystalline materials PY - 2016 SN - 0966-0941 VL - 28 IS - 5 SP - 16 EP - 20 PB - Wiley AN - OPUS4-37929 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmid, Thomas A1 - Jungnickel, R. A1 - Neuhaus, B. A1 - Riedel, Jens A1 - Kneipp, Janina A1 - Lüter, C. T1 - Raman spectroscopy as a tool for the collection management of microscope slides N2 - Throughout the history of preparation of biological samples for microscopy the choice of the mounting medium was sometimes dictated merely by availability of the used media. Thus, a plethora of resins and other organic polymers as well as complex mixtures are found to serve as mounting agents in microscope slide collections of museums of natural history, impeding the work for both curators and conservators. Dramatically, in some cases the used mounting media can already be observed to have undergone crystallization and other decomposition processes within few years of mounting demanding immediate action in restoring as well as an imminent precaution in conservation. Therefore, an unambiguous chemical identification of the used agent as well as its current aging stage is of great interest for the biologist community. The technical demands on the analytical approach to obtain this information can be straightforwardly identified. Any used technique has to be non-destructive, yield in molecular information allowing for a chemical identification of the used mounting agents and allow for a spatially well-defined interrogation in a thin sample slice, typically through a transparent cover slip. In this contribution we present a thorough study of the applicability of Raman spectroscopy for the described task. The obtained results clearly demonstrate the successful feasibility of the chosen method for a) a clear distinction between different media, b) the elucidation of the chemical composition of a multicomponent medium and c) an unambiguous identification of real unknown samples by a distinct assignment to a previously recorded spectral library. This library database was built up by recording pure mounting agents and will be provided to the general public. In combination with a Raman spectrometer, it can be an invaluable tool for future curation and conservation endeavors devoted to microscope slide collections at natural history museums. KW - Taxonomy KW - Mounting medium KW - Coverslip seal PY - 2016 DO - https://doi.org/10.1016/j.jcz.2016.07.002 SN - 0044-5231 VL - 265 SP - 178 EP - 190 PB - Elsevier AN - OPUS4-38210 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dariz, P. A1 - Neubauer, J. A1 - Goetz-Neunhoeffer, F. A1 - Schmid, Thomas T1 - Calcium aluminates in clinker remnants as marker phases for various types of 19th-century cement studied by Raman microspectroscopy N2 - In the second half of the 19th century, Roman and Portland cements played an essential role as active hydraulic binder material in building construction and façade ornamentation. Size and heterogeneous phase assemblage of unhydrated cement clinker remnants in historical cement stone differ significantly from those of remnants occurring in modern Portland cement clinker burnt in rotary kilns due to limitations of the production technology available in the 19th century (e.g., comminution and homogeneity of the feedstock, burning temperature and regime in the intermittently operated shaft kilns, grinding machinery). In the common analytical approach, thin sections and fracture surfaces of historical Roman and Portland cement mortars are characterised regarding their mineralogical composition and microstructure using optical and electron microscopic imaging techniques. Raman microspectroscopy can be additionally employed for petrographic examination, overcoming some limitations of the methods used so far. The determination of the phase content of residual cement clinker grains in the hydrated matrix allows for the differentiation of Roman and Portland cement binders. As marker phases, we propose the calcium aluminates CA, C12A7, C2AS and C3A – besides the commonly used calcium silicates C2S and C3S – because of their different formation temperatures and stability fields. This study focuses on the identification of different calcium aluminate and aluminoferrite phases in clinker remnants in samples of cast ornaments of three buildings in Switzerland raised between 1875 and 1893; the obtained Raman spectra are compared with fingerprint spectra of the corresponding pure, synthesised clinker phases collected with the same instrument for an unambiguous data interpretation. In addition to these phases, mainly minerals showing no hydraulic activity, such as, wollastonite CS, rankinite C3S2, free lime, portlandite, iron oxides, garnets, augite, albite and feldspathoids have been identified in the sampled historical cement stones by Raman microspectroscopy. As there is a strong relationship between coexisting clinker phases and the chemical composition of the raw meal as well as the burning and cooling history during clinkering, the results can help in understanding the physical and mechanical characteristics of historical cement mortars. This knowledge is fundamental for the choice and the formulation of appropriate repair materials with tailored properties employed in the field of restoration and preservation of the architectural heritage of the 19th and early 20th centuries. KW - Roman cement KW - Meso Portland cement KW - Portland cement KW - Clinker relicts KW - Raman microspectroscopy PY - 2016 DO - https://doi.org/10.1127/ejm/2016/0028-2577 SN - 0935-1221 SN - 1617-4011 VL - 28 IS - 5 SP - 907 EP - 914 AN - OPUS4-39046 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schäfer, N. A1 - Chahine, G. A. A1 - Wilkinson, A. J. A1 - Schmid, Thomas A1 - Rissom, T. A1 - Schülli, T. U. A1 - Abou-Ras, D. T1 - Microstrain distributions in polycrystalline thin films measured by X-ray microdiffraction N2 - Microstrain distributions were acquired in functional thin films by high-resolution X-ray microdiffraction measurements, using polycrystalline CuInSe2 thin films as a model system. This technique not only provides spatial resolutions at the submicrometre scale but also allows for analysis of thin films buried within a complete solar-cell stack. The microstrain values within individual CuInSe2 grains were determined to be of the order of 10^-4. These values confirmed corresponding microstrain distribution maps obtained on the same CuInSe2 layer by electron backscatter diffraction and Raman microspectroscopy. KW - Microstrain distribution KW - X-ray microdiffraction KW - Polycrystalline thin films KW - Raman microscopy PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-366592 DO - https://doi.org/10.1107/S1600576716003204 SN - 1600-5767 VL - 49 SP - 632 EP - 635 AN - OPUS4-36659 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmid, Thomas A1 - Dariz, P. T1 - Chemical imaging of historical mortars by Raman microscopy N2 - Raman microspectroscopic imaging was just recently introduced into the analysis of cement stone. Here, we demonstrate this approach on 19th-century Roman and Portland cement mortars and extend it to gypsum-based samples originating from a medieval stucco sculpture (high-burnt gypsum) and a stucco ornament prefabricated at the beginning of the 20th century (plaster of Paris). Furthermore, the distributions of dolomite and Calcite were mapped in an accessory mineral grain with approx. 500 nm lateral Resolution demonstrating the ability for studying alteration processes such as dedolomitisation. As we would like to make this approach accessible to other researchers, we discuss its present status, advantages, limitations and pitfalls. KW - Raman microscopy KW - Chemical imaging KW - Cement clinker KW - Gypsum KW - Dedolomite PY - 2016 DO - https://doi.org/10.1016/j.conbuildmat.2016.03.153 SN - 0950-0618 VL - 114 SP - 506 EP - 516 PB - Elsevier Science CY - Oxford, UK AN - OPUS4-36661 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Álvarez-García, J. A1 - Izquierdo-Roca, V. A1 - Pistor, P. A1 - Schmid, Thomas A1 - Pérez-Rodríguez, A. ED - Abou-Ras, D. ED - Kirchartz, T. ED - Rau, U. T1 - Raman spectroscopy on thin films for solar cells N2 - In the present chapter, the capabilities of Raman spectroscopy for the advanced characterisation of thin films for solar cells are reviewed. Raman spectroscopy is an optical, nondestructive technique based on the inelastic scattering of photons with elemental vibrational excitations in the material. The line shape and position of the Raman bands are determined by the crystalline structure and chemical composition of the measured samples, being sensitive to the presence of crystalline defects, impurities and strain. Presence of peaks characteristic of different phases also allows for the identification of secondary phases that are strongly related to the growth and process conditions of the films. All these aspects account for a strong interest in the analysis of the Raman spectra, providing a powerful nondestructive analytical tool for the structural and chemical assessment of the films. In addition, the combination of a Raman spectrometer with an optical microscope also allows for achieving a high spatial resolutions (of below 1 µm) when mapping surfaces and analyzing depth-resolved phase distributions in thin films. The present chapter is divided into four main sections: The two first ones are devoted to a revision of the Fundamentals of Raman spectroscopy (Section 17.2) and Vibrational modes in crystalline materials (Section 17.3). Section 17.4 deals with the main experimental considerations involved in the design and implementation of a Raman scattering setup. This is followed by a detailed description of the application of Raman scattering for the structural and chemico-physical analysis of thin film photovoltaic materials (Section 17.5), with the identification of crystalline structure and secondary phases, evaluation of film crystallinity, analysis of chemical composition of semiconductor alloys, characterisation of nanocrystalline and amorphous layers, stress effects and crystal orientations. This includes the description of corresponding state of the art and recent case examples that illustrate the capabilities of the Raman technique for the advanced characterisation of layers and process monitoring in thin-film photovoltaic technologies. KW - Thin-film solar cells KW - Polycrystalline materials KW - Raman spectroscopy KW - Raman microscopy PY - 2016 UR - http://eu.wiley.com/WileyCDA/WileyTitle/productCd-3527339922.html SN - 978-3-527-33992-1 SP - 469 EP - 499 PB - Wiley & Sons, Ltd. CY - Oxford, UK AN - OPUS4-37451 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schäfer, N. A1 - Wilkinson, A. J. A1 - Schmid, Thomas A1 - Winkelmann, Aimo A1 - Chahine, G. A. A1 - Schülli, T. U. A1 - Rissom, T. A1 - Marquardt, J. A1 - Schorr, S. A1 - Abou-Ras, D. T1 - Microstrain distribution mapping on CuInSe2 thin films by means of electron backscatter diffraction, X-ray diffraction, and Raman microspectroscopy N2 - The investigation of the microstructure in functional, polycrystalline thin films is an important contribution to the enhanced understanding of structure–property relationships in corresponding devices. Linear and planar defects within individual grains may affect substantially the performance of the device. These defects are closely related to strain distributions. The present work compares electron and X-ray diffraction as well as Raman microspectroscopy, which provide access to microstrain distributions within individual grains. CuInSe₂ thin films or solar cells are used as a modelsystem. High-resolution electron backscatter diffraction and X-ray microdiffraction as well as Ramanmicrospectroscopy were applied for this comparison. Consistently, microstrain values were determined of the order of 10⁻⁴ by these three techniques. However,only electron backscatter diffraction, X-ray microdiffraction exhibit sensitivities appropriate for mapping local strain changes at the submicrometer level within individual grains in polycrystalline materials. KW - Microstrain KW - Thin film KW - X-ray microdiffraction KW - EBSD KW - Raman microspectroscopy PY - 2016 DO - https://doi.org/10.1016/j.ultramic.2016.07.001 SN - 0304-3991 SN - 1879-2723 VL - 169 SP - 89 EP - 97 PB - Elsevier B.V. AN - OPUS4-37453 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rühlmann, Madlen A1 - Büchele, Dominique A1 - Schmid, Thomas A1 - Ostermann, Markus T1 - Development of an online-analysis technique for the determination of plant essential nutrients in soils using XRF and LIBS N2 - Currently, there is almost no comprehensive mapping of agricultural cropland because of the lack of fast and affordable mapping methods for important soil properties. Arable land of some hectares in size show a broad range of different nutrient compositions. Because of this heterogeneity wrong fertilization can occur and can cause environmental pollution or lead to smaller harvests and this is simply a waste of resources. The goal of I4S (intelligence for soil) is to develop an integrated system for site-specific soil fertility management. The I4S consortium consists of 10 different institutions, which are testing various sensors for their suitability for the requested applications. Besides the preparation of reference materials, the main task of the Federal Institute for Materials Research and Testing (BAM) in this project is the method development for online-XRF (x-ray fluorescence spectroscopy) and for online-LIBS (laser-induced breakdown spectroscopy) sensor systems. Both methods have the advantage that there is no or only little sample preparation necessary. Each method provides a fast and simultaneous multi-element analysis. Both measurement setups can be utilized for a mobile application which is fundamental for reaching the goals of I4S. Having finally a set of some reference materials, further work will focus on the online-XRF and online-LIBS methods in order to obtain useable calibration models. The calibration models will then be tested using stationary and moving samples. T2 - 12. Kolloquium Prozessanalytik CY - Berlin, Germany DA - 28.11.2016 KW - RFA KW - LIBS KW - Soil KW - Agricultural KW - Online KW - Sensor system PY - 2016 SP - P12, 63 EP - 65 AN - OPUS4-38377 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Demidov, Alexandr A1 - Eschlböck-Fuchs, S. A1 - Kazakov, Alexander Ya. A1 - Gornushkin, Igor B. A1 - Kolmhofer, P. J. A1 - Pedarnig, J. D. A1 - Huber, N. A1 - Heitz, J. A1 - Schmid, Thomas A1 - Rössler, R. A1 - Panne, Ulrich T1 - Monte Carlo standardless approach for laser induced breakdown spectroscopy based on massive parallel graphic processing unit computing N2 - The improved Monte-Carlo (MC) method for standard-less analysis in laser induced breakdown spectroscopy (LIBS) is presented. Concentrations in MC LIBS are found by fitting model-generated synthetic spectra to experimental spectra. The current version of MC LIBS is based on the graphic processing unit (GPU) computation and reduces the analysis time down to several seconds per spectrum/sample. The previous version of MC LIBS which was based on the central processing unit (CPU) computation requested unacceptably long analysis times of 10's minutes per spectrum/sample. The reduction of the computational time is achieved through the massively parallel computing on the GPU which embeds thousands of co-processors. It is shown that the number of iterations on the GPU exceeds that on the CPU by a factor > 1000 for the 5-dimentional parameter space and yet requires > 10-fold shorter computational time. The improved GPU-MC LIBS outperforms the CPU-MS LIBS in terms of accuracy, precision, and analysis time. The performance is tested on LIBS-spectra obtained from pelletized powders of metal oxides consisting of CaO, Fe2O3, MgO, and TiO2 that simulated by-products of steel industry, steel slags. It is demonstrated that GPU-based MC LIBS is capable of rapid multi-element analysis with relative error between 1 and 10's percent that is sufficient for industrial applications (e.g. steel slag analysis). The results of the improved GPU-based MC LIBS are positively compared to that of the CPU-based MC LIBS as well as to the results of the standard calibration-free (CF) LIBS based on the Boltzmann plot method. KW - Monte Carlo simulation KW - Parallel computing KW - Calibration-free laser-induced breakdown spectroscopy KW - Post-breakdown laser induced plasma KW - Quaternary oxides PY - 2016 DO - https://doi.org/10.1016/j.sab.2016.09.016 VL - 125 SP - 97 EP - 102 PB - Elsevier B.V. AN - OPUS4-38489 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eschlböck-Fuchs, S. A1 - Demidov, Alexander A1 - Gornushkin, Igor B. A1 - Schmid, Thomas A1 - Rössler, R. A1 - Huber, N. A1 - Panne, Ulrich A1 - Pedarnig, J. D. T1 - Tomography of homogenized laser-induced plasma by Radon transform technique N2 - Tomography of a laser-induced plasma in air is performed by inverse Radon transform of angle-resolved plasma images. Plasmas were induced by single laser pulses (SP), double pulses (DP) in collinear geometry, and by a combination of single laser pulses with pulsed arc discharges (SP-AD). Images of plasmas on metallurgical steel slags were taken at delay times suitable for calibration-free laser-induced breakdown spectroscopy (CFLIBS). Delays ranged from few microseconds for SP and DP up to tens of microseconds for SP-AD excitation. The white-light and the spectrally resolved emissivity ε(x,y,z) was reconstructed for the three plasma excitation schemes. The electron number density Ne(x,y,z) and plasma temperature Te(x,y,z) were determined from Mg and Mn emission lines in reconstructed spectra employing the Saha-Boltzmann plot method. The SP plasma revealed strongly inhomogeneous emissivity and plasma temperature. Re-excitation of plasma by a second laser pulse (DP) and by an arc discharge (SP-AD) homogenized the plasma and reduced the spatial variation of ε and Te. The homogenization of a plasma is a promising approach to increase the accuracy of calibration-free LIBS analysis of complex materials. KW - Plasma tomography KW - Laser induced plasma KW - Radon transform technique KW - Laser induced breakdown spectroscopy (LIBS) KW - Steel slag KW - Calibration-free analysis PY - 2016 DO - https://doi.org/10.1016/j.sab.2016.07.007 VL - 123 SP - 59 EP - 67 PB - Elsevier B.V. AN - OPUS4-37452 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmid, Thomas A1 - Schäfer, N. A1 - Levcenko, S. A1 - Rissom, T. A1 - Abou-Ras, D. T1 - Orientation-distribution mapping of polycrystalline materials by Raman microspectroscopy N2 - Raman microspectroscopy provides the means to obtain local orientations on polycrystalline materials at the submicrometer level. The present work demonstrates how orientation-distribution maps composed of Raman intensity distributions can be acquired on large areas of several hundreds of square micrometers. A polycrystalline CuInSe2 thin film was used as a model system. The orientation distributions are evidenced by corresponding measurements using electron backscatter diffraction (EBSD) on the same identical specimen positions. The quantitative, local orientation information obtained by means of EBSD was used to calculate the theoretical Raman intensities for specific grain orientations, which agree well with the experimental values. The presented approach establishes new horizons for Raman microspectroscopy as a tool for quantitative, microstructural analysis at submicrometer resolution. PY - 2015 DO - https://doi.org/10.1038/srep18410 SN - 2045-2322 VL - 5 SP - Article 18410, 1 EP - 7 PB - Nature Publishing Group CY - London AN - OPUS4-35224 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmid, Thomas A1 - Dariz, P. T1 - Shedding light onto the spectra of lime: Raman and luminescence bands of CaO, Ca(OH)2 and CaCO3 N2 - In microscopy studies of 19th-century cement stone, we found free lime in the form of darkened spherical structures, as they were described in the literature already. When trying to determine their phase composition by Raman spectroscopy, we encountered contradictive assignments in literature spectra of the lime phases CaO, Ca(OH)2 and CaCO3 and observed strong spectral features that have been ignored or erroneously assigned so far. In this study we present Raman spectra of pure lime phases and of a naturally grown calcite crystal, burnt limestone (quick lime, mainly CaO), aged slaked lime putty (mainly Ca(OH)2), and carbonated lime putty (mainly CaCO3). Based on the results, we shed light mainly onto these two questions: (1) Does CaO have a Raman spectrum? (2) Which features in the spectra are luminescence bands that could be (and already have been) misinterpreted as Raman bands? We proof our assignment of luminescence bands in lime phases by using three different laser wavelengths for excitation, and give hypotheses on the origin of the luminescence as well as practical advices on how to identify these misleading features in Raman spectra. This article is mainly addressed to users of Raman spectroscopy in different fields of material analysis who might not be aware of the presence of interfering bands in their spectra. KW - (Free) lime KW - Lime cycle KW - Lime phases KW - Calcium compounds KW - Luminescence PY - 2015 DO - https://doi.org/10.1002/jrs.4622 SN - 0377-0486 SN - 1097-4555 VL - 46 IS - 1 SP - 141 EP - 146 PB - Wiley & Sons, Ltd. CY - Chichester AN - OPUS4-32559 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Paul, Andrea A1 - Heilmann, M. T. A1 - Schmid, Thomas A1 - Maiwald, Michael T1 - Multivariate classification of Raman spectra from synthetic polymers – an approach for the improved detection of microplastics N2 - The increasing pollution of terrestrial and aquatic ecosystems with plastic debris, which leads to the accumulation of microscopic plastic particles of still unknown fate, is an upcoming problem of our time. In order to monitor the degree of contamination and to understand the underlying processes of degradation and internalization of plastic debris, analytical methods are urgently needed, which help to identify and quantify microplastics. Currently, expensive collected and purified materials enriched on filters are investigated by (micro) infrared spectroscopy (FTIR). Few studies using micro-Raman spectroscopy have been published as well. In contrast to FTIR, Raman spectroscopy can handle wet samples, but it suffers from interference of fluorescent materials. Both micro-FTIR- and micro-Raman, always include time consuming scanning and mapping procedures followed by the manual inspection and measurement of selected particles. T2 - 11. Kolloquium Arbeitskreis Prozessanalytik CY - Wien, Austria DA - 30.11.2015 KW - Prozessanalytik KW - Microplastics KW - Mikroplastik KW - Raman-Spektroskopie KW - Polymers KW - Multivariate classification PY - 2015 SP - 80 EP - 81 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-38847 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Eschlböck-Fuchs, S. A1 - Huber, N. A1 - Ahamer, C. M. A1 - Hechenberger, J. G. A1 - Kolmhofer, P. J. A1 - Heitz, J. A1 - Rössler, R. A1 - Demidov, Alexander A1 - Schmid, Thomas A1 - Gornushkin, Igor B. A1 - Panne, Ulrich A1 - Pedarnig, J. D. T1 - Application of laser-induced breakdown spectroscopy for the analysis of slags in industrial steel production N2 - Laser-induced breakdown spectroscopy (LIBS) is a fast and versatile technique for (semi) quantitative element analysis of solids, liquids, gases, and particulate matter. The LIBS method is used for optical sensing in various branches of industrial production. In the contribution we review some of our recent results on LIBS analysis of slags from secondary metallurgy in industrial steel making. Major oxides in steel slags are measured at-line and after homogenization using a calibration-free (CF) method. Two approaches for CF analysis based on the Boltzmann plot method and on the calculation of synthetic spectra are compared for the analysis of quaternary oxides. We also present the research in cooperation with our industrial partners in the process-analytical chemistry network PAC. T2 - 11. Kolloquium Arbeitskreis Prozessanalytik CY - Vienna, Austria DA - 30.11.2015 KW - Laser-induced breakdown spectroscopy (LIBS) KW - Process analytical technology KW - Steel slag PY - 2015 PB - Plandruck+ Gesellschaft m.b.H. CY - Wien AN - OPUS4-39005 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -