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 -