TY - JOUR A1 - Krahl, T. A1 - Beer, F. A1 - Relling, A. A1 - Gawlitza, Kornelia A1 - Rurack, Knut A1 - Kemnitz, E. T1 - Toward Luminescent Composites by Phase Transfer of SrF2 :Eu3+ Nanoparticles Capped with Hydrophobic Antenna Ligands N2 - Transparent dispersions of hydrophobic SrF2 :Eu3+ nanoparticles in cyclohexane with up to 20% europium were obtained by fluorolytic sol-gel synthesis followed by Phase transfer into cyclohexane through capping with sodium dodecylbenzenesulfonate (SDBS). The particles were characterized by TEM, XRD and DLS as spherical objects with a diameter between 6 and 11 nm in dry state. 1H-13CP MAS NMR experiments revealed the binding of the anionic sulfonate head group to the particle surface. The particles show bright red luminescence upon excitation of the aromatic capping agents, acting as antennas for an Energy transfer from the benzenesulfonate unit to the Eu3+ centers in the particles. This synthesis method overcomes the current obstacle of the fluorolytic sol-gel synthesis that transparent dispersions can be obtained directly only in hydrophilic solvents. To demonstrate the potential of such hydrophobized alkaline-earth fluoride particles, transparent luminescent organic-inorganic composites with 10% SrF2 :Eu3+ embedded into polyTEGDMA, polyBMA, poly-BDDMA and polyD3MA, respectively, were prepared, endowing the polymers with the luminescence features of the nanoparticles. KW - Nanoparticles KW - Fluorides KW - Sol-gel process KW - Organic-inorganic hybrid composites PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-508668 DO - https://doi.org/10.1002/cnma.202000058 SP - 1 EP - 11 PB - Wiley AN - OPUS4-50866 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Képeš, E. A1 - Gornushkin, Igor B. A1 - Pořízka, P. A1 - Kaiser, J. T1 - Tomography of double-pulse laser-induced plasmas in the orthogonal geometry N2 - The temporal evolution of laser-induced plasmas is studied in the orthogonal double-pulse arrangement. Both the pre-ablation mode (an air spark is induced above the sample surface prior to the ablation pulse) and the re-heating mode (additional energy is delivered into the plasma created by the ablation pulse) is considered. The plasmas are investigated in terms of the temporal evolution of their electron density, temperature, and volume. The plasma volumes are determined using a time-resolved tomography technique based on the Radon transformation. The reconstruction is carried out for both white-light and band-pass filtered emissivities. The white-light reconstruction corresponds to the overall size of the plasmas. On the other hand, the band-pass emissivity reconstruction shows the distribution of the atomic sample species (Cu I). Moreover, through spectrally resolved tomographic reconstruction, the spatial homogeneity of the electron density and temperature of the plasmas is also investigated at various horizontal slices of the plasmas. Our results show that the pre-ablation geometry yields a more temporally stable and spatially uniform plasma, which could be beneficial for calibration-free laser-induced breakdown spectroscopy (LIBS) approaches. On the contrary, the plasma generated in the re-heating geometry exhibits significant variations in electron density and temperature along its vertical axis. Overall, our results shed further light on the mechanisms involved in the LIBS signal enhancement using double-pulse ablation. KW - Laser-induced plasma KW - Laser-induced breakdown spectroscopy KW - Double-pulse laserinduced breakdown spectroscopy KW - Plasma tomography KW - Radon reconstruction PY - 2020 DO - https://doi.org/10.1016/j.aca.2020.06.078 SN - 0003-2670 SN - 0378-4304 VL - 1135 SP - 1 EP - 11 PB - Elsevier CY - Amsterdam AN - OPUS4-51142 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bierstedt, Andreas A1 - Warschat, Carsten A1 - You, Yi A1 - Rurack, Knut A1 - Riedel, Jens T1 - Stimulated Raman scattering by intracavity mixing of nanosecond laser excitation and fluorescence in acoustically levitated droplets N2 - Raman spectroscopy is becoming a commonly used, powerful tool for structural elucidation and species identification of small liquid samples, e.g. in droplet-based digital microfluidic devices. Due to the low scattering cross sections and the temporal restrictions dictated by the droplet flow, however, it depends on amplification strategies which often come at a cost. In the case of surface-enhanced Raman scattering (SERS), this can be an enhanced susceptibility towards memory effects and cross talk, whereas resonant and/or stimulated Raman techniques require higher instrumental sophistication, such as tunable lasers or the high electromagnetic field strengths which are typically provided by femtosecond lasers. Here, an alternative instrumental approach is discussed, in which stimulated Raman scattering (SRS) is achieved using the single fixed wavelength output of an inexpensive diode-pumped solid-state (DPSS) nanosecond laser. The required field strengths are realized by an effective light trapping in a resonator mode inside the interrogated droplets, while the resonant light required for the stimulation is provided by the fluorescence signal of an admixed laser dye. To elucidate the underlying optical processes, proof-of-concept experiments are conducted on acoustically levitated droplets, mimicking a highly reproducible and stable digital fluidic system. By using isotope-labeled compounds, the assignment of the emitted radiation as Raman scattering is firmly corroborated. A direct comparison reveals an amplification of the usually weak spontaneous Stokes emission by up to five orders of magnitude. Further investigation of the optical power dependence reveals the resulting gain to depend on the intensity of both, the input laser fluence and the concentration of the admixed fluorophore, leaving SRS as the only feasible amplification mechanism. While in this study stable large droplets have been studied, the underlying principles also hold true for smaller droplets, in which case significantly lower laser pulse energy is required. Since DPSS lasers are readily available with high repetition rates, the presented detection strategy bears a huge potential for fast online identification and characterization routines in digital microfluidic devices. KW - Ultrasonic levitation KW - Stimulated Raman Spectroscopy PY - 2020 DO - https://doi.org/10.1039/D0AY01504K VL - 12 IS - 42 SP - 5046 EP - 5054 PB - Royal Society of Chemistry AN - OPUS4-51566 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kepes, E. A1 - Gornushkin, Igor B. A1 - Pořízka, P. A1 - Kaiser, J T1 - Spatiotemporal spectroscopic characterization of plasmas induced by non-orthogonal laser ablation N2 - Ablation geometry significantly affects the plasma parameters and the consequent spectroscopic observations in laser-induced breakdown spectroscopy. Nevertheless, plasmas induced by laser ablation under inclined incidence angles are studied to a significantly lesser extent compared to plasmas induced by standard orthogonal ablation. However, inclined ablation is prominent in stand-off applications, such as the Curiosity Mars rover, where the orthogonality of the ablation laser pulse cannot be always secured. Thus, in this work, we characterize non-orthogonal ablation plasmas by applying plasma imaging, tomography, and spectral measurements. We confirm earlier observations according to which non-orthogonal ablation leads to a laser-induced plasma that consists of two distinct parts: one expanding primarily along the incident laser pulse and one expanding along the normal of the sample surface. Moreover, we confirm that the former emits mainly continuum radiation, while the latter emits mainly sample-specific characteristic radiation. We further investigate and compare the homogeneity of the plasmas and report that inclined ablation affects principally the ionic emissivity of laser-induced plasmas. Overall, our results imply that the decreased fluence resulting from inclined angle ablation and the resulting inhomogeneities of the plasmas must be considered for quantitative LIBS employing non-orthogonal ablation. KW - Radon transformation KW - Laser induced plasma KW - Plasma tomography PY - 2020 DO - https://doi.org/10.1039/d0an01996h VL - 146 IS - 3 SP - 920 EP - 929 PB - The Royal Society of Chemistry AN - OPUS4-51774 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Li, Q. A1 - Shinde, S. A1 - Grasso, G. A1 - Caroli, A. A1 - Abouhany, R. A1 - Lanzillotta, M. A1 - Pan, G. A1 - Wan, Wei A1 - Rurack, Knut A1 - Sellergren, B. T1 - Selective detection of phospholipids using molecularly imprinted fluorescent sensory core-shell particles N2 - Sphingosine-1-phosphate (S1P) is a bioactive sphingo-lipid with a broad range of activities coupled to its role in G-protein coupled receptor signalling. Monitoring of both intra and extra cellular levels of this lipid is challenging due to its low abundance and lack of robust affinity assays or sensors. We here report on fluorescent sensory core-shell molecularly imprinted polymer (MIP) particles responsive to near physiologically relevant levels of S1P and the S1P receptor modulator fingolimod phosphate (FP) in spiked human serum samples. Imprinting was achieved using the tetrabutylammonium (TBA) salt of FP or phosphatidic acid (DPPA·Na) as templates in combination with a polymerizable nitrobenzoxadiazole (NBD)-urea monomer with the dual role of capturing the phospho-anion and signalling its presence. The monomers were grafted from ca 300 nm RAFT-modified silica core particles using ethyleneglycol dimethacrylate (EGDMA) as crosslinker resulting in 10–20 nm thick shells displaying selective fluorescence response to the targeted lipids S1P and DPPA in aqueous buffered media. Potential use of the sensory particles for monitoring S1P in serum was demonstrated on spiked serum samples, proving a linear range of 18–60 μM and a detection limit of 5.6 μM, a value in the same range as the plasma concentration of the biomarker. KW - Molecularly imprinted polymers KW - Phospholipids KW - Fluorescence KW - Dye monomers PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509485 DO - https://doi.org/10.1038/s41598-020-66802-3 SN - 2045-2322 VL - 10 IS - 1 SP - 9924 PB - Nature Research CY - London AN - OPUS4-50948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gaft, M. A1 - Nagli, L. A1 - Gornushkin, Igor B. A1 - Raichlin, Y. T1 - Review on recent advances in analytical applications of molecular emission and modelling N2 - The review mainly deals with two topics that became important in applications of laser-induced breakdown spectroscopy (LIBS) in recent years: the emission of halogen- and rare-earth-containing molecules and selective excitation of molecules by molecular laser-induced fluorescence (MLIF). The first topic is related to the emission of alkaline-earth diatomic halides MX, M = Ca, Mg, Ba, Sr and X = F, Cl, Br, and I and rare-earth element (REE) oxides LaO, YO, and ScO. These molecules form in laser-induced plasma (LIP) soon after its ignition and persist for a long time, emitting broad bands in a visible part of the spectrum. They are best detected after relatively long delay times when emission from interfering plasma species (atoms and ions) has already been quenched. Such behavior of molecular spectra allows of using, for their detection, inexpensive CCD detectors equipped with simple electronic or mechanical shutters and low-resolution spectrometers. A main target for analysis by molecular spectroscopy is halogens; these elements are difficult to detect by atomic spectroscopy because their most intense atomic lines lie in the vacuum UV. Therefore, in many situations, emission from CaF and CaCl may provide a substantially more sensitive detection of F and Cl than emission from elemental F and Cl and their ions. This proved to be important in mining and concrete industries and even Mars exploration. A similar situation is observed for REEs; their detection by atomic spectroscopy sometimes fails even despite the abundance of atomic and ionic REEs' lines in the UV-VIS. For example, in minerals and rocks with low concentrations of REEs, emission from major and minor mineral elements hinders the weak emission from REEs. Many REEs do not form molecules that show strong emission bands in LIP but can still be detected with the aid of LIP. All REEs except La, Y, and Sc exhibit long-lived luminescence in solid matrices that is easily excited by LIP. The luminescence can be detected simultaneously with molecular emission of species in LIP within the same time and spectral window. The second topic is related to the combination of MLIF and LIBS, which is a technique that was proved to be efficient for analysis of isotopic molecules in LIP. For example, the characteristic spectral signals from isotopic molecules containing 10B and 11B are easier to detect with MLIF-LIBS than with laser ablation molecular isotopic spectrometry (LAMIS) because MLIF provides strong resonance excitation of only targeted isotopes. The technique is also very efficient in detection of halogen molecules although it requires an additional tunable laser that makes the experimental setup bulky and more expensive. KW - Plasma induced luminescence KW - Molecular emission KW - Laser induced plasma KW - Plasma modeling KW - Molecular analysis KW - LIBS PY - 2020 DO - https://doi.org/10.1016/j.sab.2020.105989 VL - 173 SP - 105989 PB - Elsevier B. V. AN - OPUS4-51420 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tobias, Charlie A1 - Climent Terol, Estela A1 - Gawlitza, Kornelia A1 - Rurack, Knut T1 - Polystyrene Microparticles with Convergently Grown Mesoporous Silica Shells as a Promising Tool for Multiplexed Bioanalytical Assays N2 - Functional core/shell particles are highly sought after in analytical chemistry, especially in methods suitable for single-particle analysis such as flow cytometry because they allow for facile multiplexed detection of several analytes in a single run. Aiming to develop a powerful bead platform of which the core particle can be doped in a straightforward manner while the shell offers the highest possible sensitivity when functionalized with (bio)chemical binders, polystyrene particles were coated with different kinds of mesoporous silica shells in a convergent growth approach. Mesoporous shells allow us to obtain distinctly higher surface areas in comparison with conventional nonporous shells. While assessing the potential of narrow- as well as wide-pore silicas such as Mobil composition of matter no. 41 (MCM-41) and Santa Barbara amorphous material no. 15 (SBA-15), especially the synthesis of the latter shells that are much more suitable for biomolecule anchoring was optimized by altering the pH and both, the amount and type of the mediator salt. Our studies showed that the best performing material resulted from a synthesis using neutral conditions and MgSO4 as an ionic mediator. The analytical potential of the particles was investigated in flow cytometric DNA assays after their respective functionalization for individual and multiplexed detection of short oligonucleotide strands. These experiments revealed that a two-step modification of the silica surface with amino silane and succinic anhydride prior to coupling of an amino-terminated capture DNA (c-DNA) strand is superior to coupling carboxylic acid-terminated c-DNA to aminated core/shell particles, yielding limits of detection (LOD) down to 5 pM for a hybridization assay, using labeled complementary single-stranded target DNA (t-DNA) 15mers. The potential of the use of the particles in multiplexed analysis was shown with the aid of dye-doped core particles carrying a respective SBA-15 shell. Characteristic genomic sequences of human papillomaviruses (HPV) were chosen as the t-DNA analytes here, since their high relevance as carcinogens and the high number of different pathogens is a relevant model case. The title particles showed a promising performance and allowed us to unequivocally detect the different high- and low-risk HPV types in a single experimental run. KW - Bead-based assay KW - Core-shell particles KW - Human papillomavirus KW - Mesoporous silica KW - Multiplexing PY - 2020 DO - https://doi.org/10.1021/acsami.0c17940 SN - 1944-8244 VL - 13 IS - 1 SP - 207 EP - 218 PB - American Chemical Society CY - Washington, DC AN - OPUS4-51955 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Costa, Elena A1 - Climent Terol, Estela A1 - Gawlitza, Kornelia A1 - Wan, Wei A1 - Weller, Michael G. A1 - Rurack, Knut T1 - Optimization of analytical assay performance of antibody-gated indicator-releasing mesoporous silica particles N2 - Antibody-gated indicator delivery (gAID) systems based on mesoporous silica nano- and microparticle scaffolds are a promising class of materials for the sensitive chemical detection of small-molecule analytes in simple test formats such as lateral flow assays (LFAs) or microfluidic chips. Their architecture is reminiscent of drug delivery systems, only that reporter molecules instead of drugs are stored in the voids of a porous host particle. In addition, the pores are closed with macromolecular “caps” through a tailored “gatekeeping” recognition chemistry so that the caps are opened when an analyte has reacted with a “gatekeeper”. The subsequent uncapping leads to a release of a large number of indicator molecules, endowing the system with signal amplification features. Particular benefits of such systems are their modularity and adaptability. With the example of the immunochemical detection of type-I pyrethroids by fluorescent dye-releasing gAID systems, the influence of several tuning modes on the optimisation of such hybrid sensory materials is introduced here. In particular, different mesoporous silica supports (from nano- and microparticles to platelets and short fibres), different functionalisation routes and different loading sequences were assessed. The materials’ performances were evaluated by studying their temporal response behaviour and detection sensitivity, including the tightness of pore closure (through the amount of blank release in the absence of analyte) and the release kinetics. Our results indicate that the better the paratope-accommodating Fab region of the antibody “cap” fits into the host material's pore opening, the better the closing/opening mechanism can be controlled. Because such materials are well-suited for LFAs, performance assessment included a test-strip format besides conventional assays in suspension. In combination with dyes as indicators and smartphones for read-out, simple analytical tests for use by untrained personnel directly at a point-of-need such as an aeroplane cabin can be devised, allowing for sensitivities down to the μg kg−1 range in <5 min with case-required selectivities. KW - Antibody-gated indicator delivery KW - Lateral flow assay KW - SBA-15 KW - SBA-16 KW - Type-I pyrethroids KW - Phenothrin KW - Permethrin KW - Etofenprox KW - Amplification KW - Biosensors KW - Immunoassays KW - Mesoporous particles KW - Optical detection PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-517053 DO - https://doi.org/10.1039/d0tb00371a VL - 8 IS - 22 SP - 4950 EP - 4961 PB - Royal Society of Chemistry AN - OPUS4-51705 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Climent Terol, Estela A1 - Biyikal, Mustafa A1 - Gröninger, Delia A1 - Weller, Michael G. A1 - Martínez Mánez, R. A1 - Rurack, Knut ED - Climent Terol, Estela T1 - Multiplexed Detection of Analytes on Single Test Strips with Antibody-Gated Indicator-Releasing Mesoporous Nanoparticles N2 - Rapid testing methods for the use directly at apointof need are expected to unfold their true potential especiallywhen offering adequate capabilities for the simultaneousmeasurement of multiple analytes of interest. Considering theunique modularity,high sensitivity,and selectivity of antibody-gated indicator delivery (gAID) systems,amultiplexed assayfor three small-molecule explosives (TATP, TNT,PETN) wasthus developed, allowing to detect the analytes simultaneouslywith asingle test strip at lower ppb concentrations in the liquidphase in < 5min using afluorescence reader or asmartphonefor readout. While the TNT and PETN systems were newlydeveloped here,all the three systems also tolerated harshermatrices than buffered aqueous model solutions.Besidesasingle-track strip,the outstanding modularity of the hybridbiosensor materials in combination with strip-patterningtechnologies allowed us to obtain amultichannel strip inastraightforwardmanner,offering comparable analyticalperformance while allowing to be tailored even more to theusersneed. KW - Multiplexing KW - Explosives detection KW - Gated materials KW - Fluorescence PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-518424 DO - https://doi.org/10.1002/anie.202009000 SN - 1433-7851 SN - 1521-3773 VL - 59 IS - 52 SP - 23862 EP - 23869 PB - Wiley-VCH CY - Weinheim AN - OPUS4-51842 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Qiu, Yan A1 - Yu, H. A1 - Gornushkin, Igor B. A1 - Li, J. A1 - Wu, Q. A1 - Zhang, Z. A1 - Li, X. T1 - Measurement of trace chromium on structural steel surface from a nuclear power plant using dual-pulse fiber-optic laser-induced breakdown spectroscopy N2 - Remote and on-line measurement of chromium on structural steel surface in nuclear power plants is critical for protection against fluid accelerated corrosion. To improve the insufficient sensitivity of fiber-optic laser-induced breakdown spectroscopy toward trace element detection, a dual-pulse spectral enhancement system is set up. In an iron matrix, for the purpose of improving sensitivity of trace chromium analysis and reducing the self-absorption of iron, the effects of key parameters are investigated. The optimal values of the parameters are found to be: 450 ns inter-pulse delay, 700 ns gate delay, 30 mJ/6 mJ pulse energy ratio, and 19.8 mm lens-to-sample distance (corresponding to a 799 μm laser focused spot size). Compared to the single-pulse system, the shot number of dual-pulse ablation is limited for reducing surface damage. After the optimization of the dual-pulse system, the signal-to-noise ratio of the trace chromium emission line has been improved by 3.5 times in comparison with the single-pulse system, and the self-absorption coefficient of matrix iron has been significantly reduced with self-reversal eliminated. The number of detectable lines for trace elements has more than doubled thus increasing the input for spectral calibration without significantly increasing the ablation mass. Three calibration methods including internal standardization, partial least squares regression and random forest regression are employed to determine the chromium and manganese concentrations in standard samples of low alloy steel, and the limit of detection is respectively calculated as 36 and 515 ppm. The leave-one-out cross validation method is utilized to evaluate the accuracy of chromium quantification, and the concentration mapping of chromium is performed on the surface of a steel sample (16MND5) with a relative error of 0.02 wt.% KW - Fiber-optic laser-induced breakdown spectroscopy (FO-LIBS) KW - Dual-pulse KW - Parameter optimization KW - Spectral enhancement KW - Self-absorption coefficient KW - Concentration mapping PY - 2020 DO - https://doi.org/10.1016/j.apsusc.2020.147497 SN - 0169-4332 VL - 533 IS - 147497 SP - 1 EP - 29 PB - Elsevier CY - Amsterdam AN - OPUS4-51143 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gornushkin, Igor B. A1 - Gaft, M. A1 - Nagli, L. A1 - Raichlin, Y. T1 - Laser-induced breakdown spectroscopy (LIBS) of BaF2-Tm3+ N2 - Our recent study was focused on the emission from Laser Induced Plasma (LIP) at the delay times of tenths of microseconds after the laser pulse. At these long delays, the spectrum is dominated by the broadband molecular emission and plasma induced luminescence (PIL) produced by a luminescent matrix; only solitary atomic emission lines can be seen. Barium fluoride BaF2 activated by thulium (Tm) is a famous scintillator that presents the promising object for LIP in terms of both the potential for BaF molecular emission and Tm3+ PIL. The detection of molecular and PIL bands presents a new opportunity for analysis of halogens and rare-earth elements, which are the difficult objects for LIBS. In this paper, we show that the UV, Green, Extreme Red, and Infrared molecular bands from BaF and blue luminescence from Tm3+ are present in the LIP emission spectra while the detection of atomic Emission from F I and Tm I was impossible with the same experimental setup. Thus, the detection of molecular emission and PIL can be more sensitive than the traditional detection of Emission from atoms and ions. KW - BaF KW - Laser-Induced Breakdown Spectroscopy (LIBS) KW - Rare-Earth elements (Tm3+) KW - Plasma-induced luminescence PY - 2020 DO - https://doi.org/10.1016/j.sab.2020.105767 VL - 164 SP - 105767 PB - Elsevier B.V. AN - OPUS4-50360 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gornushkin, Igor B. A1 - Sennikov, P. A1 - Kornev, R. A1 - Ermakov, A. A1 - Shkrunin, V. T1 - Laser Induced Dielectric Breakdown for Chemical Vapor Deposition by Hydrogen Reduction of Volatile Boron Halides BCl3 and  BF3 N2 - A possibility of deposition from laser-induced plasma is investigated in search for an economic and simple method for obtaining isotopic compounds from enriched gaseous precursors although no isotopic compounds are used in this the proof-of-principle work. A breakdown in mixtures of BCl3 and BCl3 with hydrogen, argon, and methane are studied both theoretically and experimentally. Equilibrium chemistry calculations show the deposition of boron, boron carbide, and carbon is thermodynamically favorable in BCl3 systems and only carbon in BF3 systems. Dynamic calculation of expanding plasma is performed using fluid dynamics coupled with equilibrium chemistry. Condensed phases of boron, boron carbide, and graphite are predicted with maximum concentrations in peripheral zones of the plasma. In experiment, plasma is induced in mixtures BCl3, H2 + BCl3, H2 + Ar + BCl3, H2 + BCl3 + CH4, BF3, H2 + BF3, H2 + Ar + BF3, and H2 + Ar + BF3. The gases are analyzed before, during, and after laser irradiation by optical and mass spectrometry methods. The results show the composition of reaction products close to that predicted theoretically. The conversion of precursor gases BCl3 and BF3 into gaseous and condensed products is 100% for BCl3 and 80% for BF3. Solid deposits of up to 30 mg are obtained from all reaction mixtures. Due to technical reasons only FTIR characterization of the BCl3 + H2 + CH4 deposit is done. It points to presence of condensed boron and boron carbide predicted by the model. Overall, the calculations and preliminary experimental results imply the chemical vapor deposition with laser induced plasma is promising for conversion of gaseous enriched precursors into elemental isotopes and their isotopic compounds. KW - Boron halides KW - Chemical vapor deposition KW - Laser induced dielectric breakdown, Hydrogen reduction PY - 2020 DO - https://doi.org/10.1007/s11090-020-10096-w VL - 40 IS - 5 SP - 1145 EP - 1162 PB - Springer AN - OPUS4-50968 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gornushkin, Igor B. A1 - Sennikov, P. A1 - Kornev, R. A1 - Ermakov, A. A1 - Shkrunin, V. A1 - Polyakov, V. T1 - Laser induced dielectric breakdown for synthesis of chlorofluorosilanes N2 - Tetrafluorosilane (SF4) and tetrachlorosilane (SiCl4) plasmas have been widely used as a source of either F or Cl for etching silicon or as a source of silicon for deposition of Si-based materials. Using different combinations of F and Cl in molecules of chlorofluorosilane SiFxCly adds additional flexibility in realization of these processes. Direct synthesis of SiFxCl4-x (x=1, 2, 3) from SiF4 and SiCl4 is thermodynamically forbidden under standard conditions. This restriction is removed in low-temperature plasmas studied in this work: a laser induced dielectric breakdown (LIDB) plasma and steady-state inductively-coupled plasma (ICP). The plasmas differ in many respects including energy content, temperature, and electron density that lead to different ionization/excitation states of plasma species, which are observed from plasma optical emission spectra. IR spectroscopy and mass-spectrometry confirm the formation of three chlorofluorosilanes, SiF3Cl, SiF2Cl2, and SiFCl3 that constitute ~60% in products of LIDB plasma and split 50/50 between SiF3Cl, SiFCl3 and SiF2Cl2. Experimental observations are verified by equilibrium static calculations via the minimization of Gibbs free energy and by dynamic calculations via the chemical-hydrodynamic plasma model of a spherically expanding plasma plume. The both types of calculations qualitatively agree with the results of spectroscopic analysis and reproduce dominant presence of SiF2Cl2 as the temperature of the gas approaches the room temperature. KW - Chemical-hydrodynamic modeling KW - Chlorofluorosilanes KW - Laser induced dielectric breakdown KW - Inductively coupled plasma KW - Equilibrium chemical modeling PY - 2020 DO - https://doi.org/10.1016/j.jfluchem.2020.109692 VL - 241 SP - 109692 PB - Elsevier B.V. AN - OPUS4-51646 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gottlieb, Cassian A1 - Gojani, Ardian A1 - Völker, Tobias A1 - Günther, Tobias A1 - Gornushkin, Igor B. A1 - Wilsch, Gerd A1 - Günster, Jens T1 - Investigation of grain sizes in cement-based materials and their influence on laser-induced plasmas by shadowgraphy and plasma imaging N2 - The effect of particle grain sizes in different cement-based mixtures on the laser-induced plasma evolution is studied using two experimental methods: (i) temporal and spatial evolution of the laser-induced shock wave is investigated using shadowgraphy and two-dimensional plasma imaging, and (ii) temporal and spatial distribution of elements in the plasma is investigated using two-dimensional spectral imaging. This study is motivated by the interest in applying laser-induced breakdown spectroscopy (LIBS) for chemical analysis of concrete, and subsequently obtain information related to damage assessment of structures like bridges and parking decks. The distribution of grain sizes is of major interest in civil engineering as for making concrete different aggregate grain sizes defined by a sieving curve (64mm to 0.125 mm) are needed. Aggregates up to a size of 180 μm can be excluded from the data set, therefore only the amount of small aggregates with a grain size below 180 μm must be considered with LIBS. All components of the concrete with a grain size smaller than 0.125mm are related to the flour grain content. Tested samples consisted of dry and hardened cement paste (water-cement ratio w/z=0.5), which served as a reference. Aggregate mixtures were made by adding flour grains (size 40 μm) and silica fume (size 0.1 μm) in different ratios to cement: 10%, 30%, 50% and 60%, all combined to the remaining percentage of dry or hydrated cement. The visualization results show that a dependance in the evolution of the plasma as a function of sample grain size can be detected only in the initial stages of the plasma formation, that is, at the initial 3 μs of the plasma life. Spectral information reveals the elemental distribution of the silicon and calcium in plasma, in both neutral and ionized form. Here also, a significant effect is observed in the first 1 μs of the plasma lifetime. KW - LIBS KW - Cement-based materials KW - Particle size KW - Shadowgraphy KW - Plasma imaging PY - 2020 DO - https://doi.org/10.1016/j.sab.2020.105772 VL - 165 SP - 105772 PB - Elsevier B.V. AN - OPUS4-50319 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sennikov, P. A1 - Gornushkin, Igor B. A1 - Kornev, R. A1 - Nazarov, V. A1 - Polyakov, V. A1 - Shkrunin, V. T1 - Hydrogen Reduction of MoF6 and Molybdenum Carbide Formation in RF Inductively Coupled Low‑Pressure Discharge: Experiment and Equilibrium Thermodynamics Consideration N2 - The physical plasma parameters, temperature and electron number density, are studied in the RF-IC (RF inductively coupled) discharge at a reduced pressure of 3 Torr in mixtures of MoF6 with Ar, H2 and CH4. The emission spectra of mixtures are investigated. It is shown that in the presence of argon, the concentration of free electrons in plasma and dissociation rate of MoF6 increase. A main role of molecular hydrogen is the generation of atomic hydrogen that binds atomic fuorine and leads to the formation of gaseous and solid products. Exhaust gas mixtures exiting the reactor are analyzed by mass spectrometry. It is shown that for all cases, the conversion of MoF6 into reaction products is close to 100%. A thermodynamic analysis of the equilibrium composition of MoF6 systems with Ar, H2 and CH4 was carried out and the obtained results are in good agreement with experimentally observed composition of the solid and gas phases. Analysis of solid deposits from mixture MoF6/H2/Ar revealed the presence of molybdenum powder and large amount of amorphous MoFx. The deposit obtained from mixtures with methane, MoF6/H2/Ar/CH4, contained crystalline molybdenum carbide, Mo3C2. KW - Molybdenum carbide KW - RF ICP discharge KW - Reduction of MoF6 KW - Thermodynamic KW - Molybdenum PY - 2020 DO - https://doi.org/10.1007/s11090-020-10138-3 SN - 0272-4324 VL - 41 IS - 2 SP - 673 EP - 690 PB - Springer AN - OPUS4-51569 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zettner, Alina A1 - Gojani, Ardian A1 - Schmid, Thomas A1 - Gornushkin, Igor B. T1 - Evaluation of a Spatial Heterodyne Spectrometer for Raman Spectroscopy of Minerals N2 - Spatial heterodyne spectroscopy (SHS) is a novel spectral analysis technique that is being applied for Raman spectroscopy of minerals. This paper presents the theoretical basis of SHS and its application for Raman measurements of calcite, quartz and forsterite in marble, copper ore and nickel ore, respectively. The SHS measurements are done using a broadband (518–686 nm) and resolving power R ≈ 3000 instrument. The spectra obtained using SHS are compared to those obtained by benchtop and modular dispersive spectrometers. It is found that SHRS performance in terms of resolution is comparable to that of the benchtop spectrometer and better than the modular dispersive spectrometer, while the sensitivity of SHRS is worse than that of a benchtop spectrometer, but better than that of a modular dispersive spectrometer. When considered that SHS components are small and can be packaged into a handheld device, there is interest in developing an SHS-based Instrument for mobile Raman spectroscopy. This paper evaluates the possibility of such an application. KW - Forsterite KW - Spatial heterodyne spectrometer KW - Interferometric spectroscopy KW - Fourier transform spectroscopy KW - Raman spectroscopy KW - Calcite KW - Quartz PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-504624 DO - https://doi.org/10.3390/min10020202 VL - 10 IS - 2 SP - 202 PB - MDPI CY - Basel, Switzerland AN - OPUS4-50462 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gornushkin, Igor B. A1 - Sennikov, P. G. A1 - Kornev, R. A. A1 - Polyakov, V. S. T1 - Equilibrium calculations for plasmas of volatile halides of III, IV and VI group elements mixed with H2 and H2 + CX4 (X = H, Cl, F) relevant to PECVD of isotopic materials N2 - The composition of hydrogen and hydrogen-methane plasmas containing ~10% of BX₃, SiX₄, GeX₄ (X = F, Cl), SF₆, MoF₆ and WF₆ is calculated for the temperature range ~300-4000 K using the equilibrium chemical model. The calculations provide valuable information about thermodynamic parameters (pressure, temperature) needed for condensation of pure elements (in H₂ plasma) and their carbides (in H₂ + CH₄ plasma) and about intermediate reaction products. Using volatile fluorides for plasma chemical deposition alleviates obtaining monoisotopic elements and their isotopic compounds because fluorine is monoisotopic. PECVD is promising method for one-step conversion of fluorides to elemental isotopes and their carbides. For fluorides, further insight is needed into properties of plasmas supported by different types of discharges. KW - Plasma chemistry KW - Modeling chemical reactions KW - Plasma enhanced chemical vapor deposition KW - Reduction of volatile chlorides and fluorides by hydrogen PY - 2020 DO - https://doi.org/10.1007/s10967-020-07295-2 VL - 326 IS - 1 SP - 407 EP - 421 PB - Springer CY - Dordrecht AN - OPUS4-51144 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Huan, Y. A1 - Gojani, Ardian A1 - Gornushkin, Igor B. A1 - Wang, X. A1 - Liu, D. A1 - Rong, M. T1 - Dynamics of laser-induced plasma splitting N2 - The dynamics of laser-induced plasma plume splitting is investigated using spatiotemporal plasma imaging and spectrometry in this paper. Plasma plume splitting into fast and slow components is clearly observed using plasma optical emission as time evolves. The spatial resolved plasma spectra are used to investigate the plasma species distribution, which reveals that the charged copper ions, which radiate at wavelength range 485 nm - 504 nm, are merely present in the fast component. In order to further interpret the mechanism, the pressure-dependent and laser energy-dependent plume splitting are analyzed. Based on the results, the charge separation field is proposed to explain this phenomenon. This work can be of importance for such areas as laser induced breakdown spectroscopy, laser-induced ion source formation, pulse laser deposition, film growth, and nanoscale synthesis. KW - Spectroscopy KW - Laser induced plasma KW - Splitting KW - Imaging PY - 2020 DO - https://doi.org/10.1016/j.optlaseng.2019.105832 SN - 0143-8166 VL - 124 SP - 1 EP - 5 PB - Elsevier CY - Amsterdam AN - OPUS4-48746 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Climent Terol, Estela A1 - Gotor, Raul A1 - Tobias, Charlie A1 - Bell, Jérémy A1 - Martin-Sanchez, Pedro A1 - Rurack, Knut T1 - Dip Sticks Embedding Molecular Beacon-Functionalized Core−Mesoporous Shell Particles for the Rapid On-Site Detection of Microbiological Fuel Contamination N2 - Microbial contamination of fuels by fungi and bacteria presents risks of corrosion and fuel system fouling. In this work, a rapid test for the determination of microbial genomic DNA from aqueous fuel extracts is presented. It combines test strips coated with polystyrene core/mesoporous silica shell particles, to the surface of which modified fluorescent molecular beacons are covalently grafted, with a smartphone detection system. In the hairpin loop, the beacons incorporate a target sequence highly conserved in all bacteria, corresponding to a fragment of the 16S ribosomal RNA gene, which is also present to a significant extent in the 18S rRNA gene of fungi, allowing for broadband microbial detection. In the developed assay, the presence of genomic DNA extracts from bacteria and fungi down to ca. 20−50 μg L−1 induced a distinct fluorescence response. The optical read-out was adapted for on-site monitoring by combining a 3D-printed case with a conventional smartphone, taking advantage of the sensitivity of contemporary complementary metal oxide semiconductor (CMOS) detectors. Such an embedded assembly allowed to detect microbial genomic DNA in aqueous extracts down to ca. 0.2−0.7 mg L−1 and presents an important step toward the on-site uncovering of fuel contamination in a rapid and simple fashion. KW - Bacteria KW - Fungi KW - Rapid test KW - Fluorescence KW - Smartphone KW - Biofouling PY - 2020 DO - https://doi.org/10.1021/acssensors.0c01178 SN - 2379-3694 VL - 6 IS - 1 SP - 27 EP - 34 PB - American Chemical Society CY - Washington, DC AN - OPUS4-51956 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Costa, Elena A1 - Climent Terol, Estela A1 - Ast, S. A1 - Weller, Michael G. A1 - Canning, J. A1 - Rurack, Knut T1 - Development of a lateral flow test for rapid pyrethroid detection using antibody-gated indicator-releasing hybrid materials N2 - The employment of type-I pyrethroids for airplane disinfection in recent years underlines the necessity to develop sensing schemes for the rapid detection of these pesticides directly at the point-of-use. Antibody-gated indicator-releasing materials were thus developed and implemented with test strips for lateral-flow assay-based analysis employing a smartphone for readout. Besides a proper matching of pore sizes and gating macromolecules, the functionalization of both the material's outer surface as well as the strips with PEG chains enhanced system performance. This simple assay allowed for the detection of permethrin as a target molecule at concentrations down to the lower ppb level in less than 5 minutes. KW - Lateral flow test KW - Gated hybrid material KW - Fluorescence KW - Smartphone readout device KW - Pyrethroid KW - Pesticide KW - Insecticide KW - SBA-15 KW - Permethrin PY - 2020 DO - https://doi.org/10.1039/d0an00319k SN - 0003-2654 SN - 1364-5528 VL - 145 IS - 10 SP - 3490 EP - 3494 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-50756 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Galbacs, G. A1 - Keri, A. A1 - Kalomista, I. A1 - Kovacs-Szeles, E. A1 - Gornushkin, Igor B. T1 - Deuterium analysis by inductively coupled plasma mass spectrometry using polyatomic species: An experimental study supported by plasma chemistry modeling N2 - based on the use of the signal from hydrogen-containing polyatomic ions formed in the inductively coupled plasma. Prior to analytical experiments, a theoretical study was performed to assess the concentration of polyatomic species present in an equilibrium Ar-O-D-H plasma, as a function of temperature and stoichiometric composition. It was established that the highest sensitivity and linearity measurement of D concentration in a wide range can be achieved by monitoring the ions of D2 and ArD, at masses 4 and 42, respectively. Results of the calculations are in good agreement with the experiments. Signal stability, spectral interferences, as well as the effect of plasma parameters were also assessed. Under optimized conditions, the limit of detection (LOD) was found to be 3 ppm atom fraction for deuterium when measured as ArD (in calcium and potassium free water), or 78 ppm when measured as D2. The achieved LOD values and the 4 to 5 orders of magnitude dynamic range easily allow the measurement of deuterium concentrations at around or above the natural level, up to nearly 100% (or 1 Mio ppm) in a standard quadrupole ICP-MS instrument. An even better performance is expected from the method in high resolution ICP-MS instruments equipped with low dead volume sample introduction systems KW - ICP MS KW - Deuterium KW - Deuterium enriched water PY - 2020 DO - https://doi.org/10.1016/j.aca.2020.01.011 VL - 1104 SP - 28 EP - 37 PB - Elsevier B.V. AN - OPUS4-50777 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -