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Recent advances in the liquid-phase exfoliation enabled large-scale production of two-dimensional (2D) materials, including few-layer graphene and transition metal dichalcogenides. The exfoliated flakes of 2D materials allow cost-effective deposition of continuous films for various applications ranging from optoelectronics to lubrication technology. The self-assembly of 2D materials on water subphase and subsequent transfer of such a Langmuir film onto a solid substrate offers an unprecedented layer quality in terms of spatial homogeneity as it proceeds in thermodynamic equilibrium. However, while the formation of conventional organic molecular Langmuir films has been widely studied, the application of the Langmuir technique to rigid inorganic 2D materials is still rather unexplored. Here, we study the underlying mechanism behind the formation and collapse at the critical surface pressure of the Langmuir film composed of few-layer MoS2 flakes. The in situ wide-angle X-ray scattering measured in real time and other supportive techniques applied ex situ after the film transfer onto a Si/SiO2 substrate were employed. We identify all principal compression stages up to the Langmuir monolayer collapse and beyond, relying on the texture, surface pressure, and elastic modulus temporal evolution. The results obtained and the conclusions drawn can be extended to a large family of the inorganic Langmuir films of other 2D materials to optimize the deposition process for envisaged application.

Tungsten (W) and its alloys are being considered as a major candidate for the plasma-facing components (PFCs) in future fusion devices. Being versatile and able to perform in situ measurements, laser-induced breakdown spectroscopy (LIBS) is the most promising analytical tool for the elemental characterization of fusion-relevant materials. The present article studies the use of calibration free (CF)-LIBS for the characterization of the plasma generated from tantalum (Ta) and elemental quantification of WTa (5 at.%) + Deuterium (D) (10 at.%) sample (coating thickness ~ 3 µm) on molybdenum (Mo) substrate, using a high energy Nd:YAG laser (1064 nm, pulse duration 8 ns). The laser energy has been optimized (58 mJ/pulse) for given samples, and the laser-induced plasma was generated on the surface by means of focussing the laser. All the experimental measurements have been performed in air at atmospheric pressure and room temperature. For the quantification of WTa + D coating, measurements have also been performed under the flow of nitrogen gas. For the detection of the analytes, both gate delay (td) and gate width (tg) were optimized. For the CF quantification, it has been found that the most appropriate gate times were td = tg = 1 µs, considering thermodynamic equilibrium. Suitable emission from both neutral and ionic species has been considered for the evaluation of the plasma temperature and electron density using the Boltzmann and Saha–Boltzmann plots approaches, respectively. This work provides a step towards CF-LIBS quantification and depth profile analysis studies for WTa-based materials and D retention in it. These results have been compared with those obtained by other analytical techniques (TOF-ERDA and GDOES).

Few-layer MoS2 films stay at the forefront of current research of two-dimensional materials. At present, continuous MoS2 films are prepared by chemical vapor deposition (CVD) techniques. Herein, we present a cost-effective fabrication of the large-area spatially uniform films of few-layer MoS2 flakes using a modified Langmuir-Schaefer technique. The compression of the liquid-phase exfoliated MoS2 flakes on the water subphase was used to form a continuous layer, which was subsequently transferred onto a submerged substrate by removing the subphase. After vacuum annealing, the electrical sheet resistance dropped to a level of 10 kΩ/sq, being highly competitive with that of CVD-deposited MoS2 nanosheet films. In addition, a consistent fabrication protocol of the large-area conductive MoS2 films was established. The morphology and electrical properties predetermine these films to advanced detecting, sensing, and catalytic applications. A large number of experimental techniques were used to characterize the exfoliated few-layer MoS2 flakes and to elucidate the formation of the few-layer MoS2 Langmuir film.

In this work, Calibration Free - Laser Induced Breakdown Spectroscopy is applied for the qualitative and quantitative elemental analysis in the rib bone of a wild boar, which is a complex matrix. The sample was obtained from the rib bone of a wild boar. The sample contains major elements such as calcium and phosphorus and other minor and trace elements such as magnesium and strontium, among others. The LIBS application provided by NIST was used for the simulation of the plasma cooling. The intensities of emission lines were calculated at different conditions (varying plasma temperature Te and electron density ne simultaneously) depending on the plasma cooling process. The obtained results allowed the determination of the range of suitable values of ne and Te for the experimental measurements and optimization of the Saha-Boltzmann plot. The sample was measured for delay times of 100, 300, 500 and 1000 ns at a low pressure of 13 mbar in an argon atmosphere. From the measured data, suitable lines of Ca, Mg, P, Sr, O, and H were identified and chosen in Vacuum UV – NIR range for the reliable calculation of the Te of plasma for the bone sample for different delays. The Ca/P was obtained by calculating the atomic and mass percentages of the elements present in the bone sample.

openaire: EC/H2020/633053/EU//EUROfusion A remote LIBS system is being considered as an analysis tool in ITER for monitoring the erosion and fuel retention in the first wall. This necessitates further investigation of the performance of LIBS for thick co-deposited layers consisting of ITER-relevant materials. The main goal of this work is determining the fuel content of the samples and D depth profile by LIBS and to compare the results with those obtained by other methods. The studied samples were Be-based mixed coatings on W substrates, containing D and in some cases C, O, or both. These impurities are relevant not only for ITER, but also for other fusion devices, such as JET-ILW. The laser ablation was performed at 10 mbar Ar pressure using a 5 ns pulse Nd:YAG laser at 1064 nm. Suitable Be and Ar spectral lines were employed for the evaluation of the electron temperature of the plasma using multi-elemental Saha-Boltzmann (MESB) plots. The electron density was obtained from the Stark broadening of the Dα and Hα spectral lines following deconvolution. The average elemental content of each coating was then obtained by calibration-free LIBS (CF-LIBS) and are in agreement with other techniques (TOF–ERDA, IBA).

The growth of the pharmaceutical industry to keep pace with the well-being of humans worldwide has posed many challenges related to quality control. This paper reports on the potential application of a modern optical spectroscopic technique popularly known as laser-induced breakdown spectroscopy (LIBS) to address some quality aspects such as the sample constituents, hardness, and classification of five different pharmaceutical samples. The surface analysis of these samples has been carried out using optical microscopy (OM) and atomic force microscopy (AFM). The LIBS spectra of different pharmaceutical samples of different brands have been recorded in air at atmospheric pressure using a high-energy Nd:YAG laser and an echelle spectrometer coupled with an intensified charge-coupled device camera. The LIBS spectrum provides the spectral signatures of lighter elements like carbon (C), hydrogen (H), nitrogen (N), oxygen (O), and the CN violet band, along with inorganic elements like calcium (Ca), magnesium (Mg), etc. Two different multivariate analysis methods, principal component analysis (PCA) and artificial neural network (ANN), have been employed with the LIBS spectral data matrix to obtain the classification of these samples. OM and AFM were used to investigate the surface quality of the tablets, which helps the pharmaceutical industry in increasing the life of pharmaceutical products. The LIBS-based hardness of the sample matrices is estimated, and a correlation has been established with AFM-based RMS roughness. The results illustrate the strength of the LIBS coupled with multivariate analysis like PCA and ANN for a rapid and reliable analysis of pharmaceutical products. Also, LIBS coupled with OM and AFM might be an effective way to address surface quality aspects of pharmaceutical samples.

Tungsten-based materials are possible candidates as PFCs in future fusion devices. LIBS is one of the most suitable techniques for monitoring erosion and deposition processes including fuel retention, due to its versatility and ability to perform in situ measurements. By deploying ps-LIBS, instead of ns, the laser ablation occurs with fewer melting effects. This work compares ns- and ps- (CF)-LIBS characterization of WZr(D) samples, at the linear plasma generator at Magnum-PSI at the DIFFER. The laser energy has been optimized for both laser regimes, lowering the laser energy for the ns regime (from 19.9 mJ pulse−1 to 7.4 mJ pulse−1) to approximate to ps regime (0.3 mJ pulse−1). All the experimental measurements have been performed at Patm. The pure WZr samples have been analyzed in ambient air, while the WZrD sample measurements have been performed under Ar gas flow. The retained deuterium content varies from 4 at% to 0.3 at%.

To overcome the erosion of the plasma-facing materials (PFMs) inside a fusion reactor, liquid metals such as lithium or tin are being explored as potential PFMs in fusion reactors due to their several advantages such as self-repair or high-power exhaust capability. Lithium can reduce the oxygen and carbon impurity contamination by chemically binding these species to the wall. Thus, experiments of power handling performance with a special liquid metal (Li) divertor module based on the capillary porous system technology were performed in the tokamak COMPASS. The elemental analysis of 14 screw samples located around the vacuum vessel provides information about the migration of evaporated/redeposited liquid elements. The main goal of this work is to characterize and quantify screws containing Li-based coating by LIBS by measuring the quantitative elemental composition. The studied samples were Li-coated Ni-Cr-based screws. The laser ablation was performed in air at atmospheric pressure using a 5 ns pulse Nd:YAG laser at 1064 nm. Suitable Li I, Ca I-II, and Fe I spectral lines were employed for the evaluation of the electron temperature of the plasma using multi-elemental Saha-Boltzmann plots. The electron density was obtained from the Stark broadening of the Hα spectral line. The elemental content of each sample was then obtained by calibration-free LIBS (CF-LIBS).

It is generally accepted that liquid-phase exfoliation (LPE) enables large-scale production of few-layer MoS2 flakes. In our work, we studied in detail few-layer MoS2 oxidation in the course of standard LPE in a water/ethanol solution. We demonstrate that an increase of the initial MoS2 concentration above a certain threshold triggers a pronounced oxidation and the exfoliation process starts to produce MoOx nanoparticles. A subsequent decrease of the water pH along with an increased content of SO42- suggests an oxidation scenario of few-layer MoS2 oxidation towards MoOx nanoparticles. Moreover, the lowered pH leads to agglomeration and sedimentation of the few-layer MoS2 flakes, which significantly lowers their production yield. We employed a large number of physico-chemical techniques to study the MoS2-to-MoOx transformation and found a threshold value of 10 mg ml-1 of the initial MoS2 concentration to trigger this transformation.

The elemental quantification of liquid metal divertor (LMD) surface is important for understanding the material erosion, migration, re-deposition, and fuel retention in Plasma-Facing Components (PFCs). Currently, LMD are attractive candidates for the short- and long-term operation of fusion devices like DEMO. Liquid metals can provide self-cooling, self-replenishing plasma-facing surfaces requiring very little upkeep. In a previous work, we studied Li and LiSn layers deposited on attachment screws in the COMPASS tokamak by means of Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS). Several problems were encountered related to the detection of Sn in LiSn. Thus, in the present work, we are optimizing the experimental conditions for the detection of Sn I-II and Pb I-II in Pb-containing Sn-based alloys, performing the quantification of Pb in traces and in bulk quantities using CF-LIBS approach.

We developed a method for sensitive elemental analysis of wines using laser-induced breakdown spectroscopy (LIBS). In order to overcome the inefficiency of direct ablation of bulk wine (an organic liquid), a thin layer of wine residue was prepared on a metallic target according to an appropriated heating procedure applied to an amount of liquid wine dropped on the target surface. The obtained ensemble was thus ablated. Such a sample preparation procedure used a very small volume of 2 mL of wine and took only 30 min without reagent or solvent. The results show the detection of tens of metal and non-metal elements including majors (Na, Mg, K, Ca), minors, and traces (Li, B, Si, P, Ti, Mn, Fe, Cu, Zn, Rb, Sr, Ba, and Pb) in wines purchased from local supermarkets and from different production places in France. Commercially available wines were then spiked with certified standard solutions of Ti and Fe. Three series of laboratory reference samples were thus prepared using three different wines (a red wine and a white wine from a same production region and a red wine from another production region) with concentrations of Ti and Fe in the range of 1–40 mg/L. Calibration graphs established with the spiked samples allowed extracting the figures-of-merit parameters of the method for wine analysis such as the coefficient of determination ( R2) and the limits of detection and quantification (LOD and LOQ). The calibration curves built with the three wines were then compared. We studied the residual matrix effect between these wines in the determination of the concentrations of Ti and Fe.

Laser-induced breakdown spectroscopy (LIBS) for composition analysis of polymer materials results in optical spectra containing atomic and ionic emission lines as well as molecular emission bands. In the present work, the molecular bands are analyzed to obtain spectroscopic information about the plasma state in an effort to quantify the content of different elements in the polymers. Polyethylene (PE) and a rubber material from tire production are investigated employing 157 nm F2 laser and 532 nm Nd:YAG laser ablation in nitrogen and argon gas background or in air. The optical detection reaches from ultraviolet (UV) over the visible (VIS) to the near infrared (NIR) spectral range. In the UV/VIS range, intense molecular emissions, C2 Swan and CN violet bands, are measured with an Echelle spectrometer equipped with an intensified CCD camera. The measured molecular emission spectra can be fitted by vibrational-rotational transitions by open access programs and data sets with good agreement between measured and fitted spectra. The fits allow determining vibrational-rotational temperatures. A comparison to electronic temperatures Te derived earlier from atomic carbon vacuum-UV (VUV) emission lines show differences, which can be related to different locations of the atomic and molecular species in the expanding plasma plume. In the NIR spectral region, we also observe the CN red bands with a conventional CDD Czerny Turner spectrometer. The emission of the three strong atomic sulfur lines between 920 and 925 nm is overlapped by these bands. Fitting of the CN red bands allows a separation of both spectral contributions. This makes a quantitative evaluation of sulfur contents in the start material in the order of 1 wt% feasible.

In ITER, a remote handling laser-induced breakdown spectroscopy (LIBS) system is considered to be able to observe regions where deposition of thick layers is expected to occur and assess the retention of fuel on wall structures. The H and D contents of surface layers on divertor and first-wall materials have been intensely studied by LIBS but mostly by depth profile analysis of D. As far as we know, quantitative analysis of H/D in BeW mixed layer by calibration free-LIBS (CF-LIBS) has not been performed. Thus, the aim of this work is the quantification of the relative concentrations of D and H in Be-based material samples by CF-LIBS. The samples used were Be/W(67:33) as mixed homogeneous coatings (2 μm) on Mo substrates. Laser ablation was performed using a 1064 nm laser with 5 ns pulses. In order to enhance the resolution to distinguish H, D and in future T from each other, two different pressures were used: high vacuum and 0.5 mbar of Ar. Suitable Be and W spectral lines (without interferences and self-absorption) have been selected for precise evaluation of the electron temperature, T e , of the plasma using the Boltzmann plots. The electron density, n e , was extracted from the Saha equation using the average electron temperatures obtained from the Stark broadening of the H α line. With these values, the D content of the samples has been calculated by CF LIBS as ∼4.7% ± 2.9%. These results are in a good agreement with thermal desorption spectroscopy measurements, which gives a 4–5 at% for the D content. In addition, the depth profile is similar to that recorded using secondary ion mass spectrometry.

Few-layer MoS

It is generally accepted that liquid-phase exfoliation (LPE) enables large-scale production of few-layer MoS

The elemental analysis of plasma-facing components (PFCs) with deposits is vital for the study of the material erosion, deposition, and fuel retention. For ITER-like divertor, first wall is formed by W-based deposit containing Be, O, D, H and other impurities. The quantification of fuel retention in these materials, including the depth dependence of the fuel retention and the elemental composition, is important. Calibration free laser-induced breakdown spectroscopy (CF-LIBS) is the only technique possible for online remote diagnostics with recognition of the hydrogen isotopes. But the most commonly used ns-LIBS leads to material's overheating; thus, larger non-realistic retention of hydrogen isotopes is generally obtained. In this work, we report the quantitative ps- and ns-CF LIBS analysis of W-based model material (WCu). A WCu alloy has been selected to permit the analysis of tungsten spectral lines in a binary alloy with an element with not too many weak lines. Surface experiments are performed by LIBS using ~30 ps and 5 ns, 1064 nm laser pulses at atmospheric pressure. One of the advantages of ps laser is that it ablates the surface more efficiently, without overheating the ablated material. The laser ablation threshold for the plasma creation in the ps regime is situated at lower energy, thus less material is needed and better depth resolution can be obtained. Suitable Cu and W spectral lines have been selected for the precise evaluation of the electron temperature using the Saha-Boltzmman plots. The electron density values were found from the Saha-Boltzmann plots and the Stark broadening of the Hα spectral line. The results demonstrate the successful detection of W and Cu spectral lines using ps- and ns-LIBS and its quantification.

The ablation and fuel-retention characteristics of aluminum–tungsten (AlW) and beryllium–tungsten (BeW) samples have been determined using Laser Induced Breakdown Spectroscopy (LIBS) and compared to results obtained using Secondary Ion Mass Spectrometry (SIMS). The measurements have been made both at vacuum (of the order of 10−4Pa) and at 50Pa of argon to especially enhance the intensities of the spectral lines of H and D. For reliable evaluation of the ablation rate of the samples the electron density ne and temperature Te of the LIBS plasma have been determined with the help of selected of spectral lines of Be, Al, and W. The electron density ne has been obtained from Stark broadening lines of Al I (308.7nm and 394.4nm) and Be I (457.3nm) and Te from the Saha–Boltzmann plot using W I and W II spectral lines having a higher value of the energy of upper states in order to prevent the influence of self-absorption on the results. The results indicate similar ablation characteristics between AlW (AlWD) and BeW (BeWD) samples but the inclusion of deuterium in the coating increases the ablation rate by a factor of 10 for both sample types. Concerning fuel retention more than one order of magnitude less D is retained in the AlWD sample than in BeWD. In the presence of background argon, the H and D lines were stronger and more easily distinguishable. This is a positive sign considering the real application in ITER where LIBS measurements are foreseen to be done during maintenance breaks. However the higher pressure gave a better signal, it is still far from the measurement conditions planned for ITER which need to be tested separately. Keywords: LIBS, Beryllium, Aluminum

Fusion energy has great potential over other sources of energies due to the abundance of fusion fuel on the Earth and tokamak has turns out to be the best technique to harvest fusion energy. However, a continuous operation of a tokamak involves challenges due to plasma-wall interaction, e.g. erosion, re-deposition, fuel retention, and impurities control. For an efficient operation, the tokamak wall has to be remotely monitored and laser-induced breakdown spectroscopy (LIBS) seems to be the most suitable technique for this purpose. Multiple LIBS techniques (e.g. back-collection, VUV LIBS, DP-LIBS) for this purpose are reviewed in this contribution. The role of pressure, excitation wavelength and atmospheric effect has also been discussed. LIBS studies of spatial and depth profiles of W, Be, Al, Mo, Li, C based materials with impurities are presented as well and compared to other analytical methods. At last, the measurement of layer-wise matrix hardness is also discussed.

Power handling experiments with a special liquid metal divertor module based on the capillary porous system technology were performed in the tokamak COMPASS. The performance of two metals (Li and LiSn alloy) were tested for the first time in a divertor under ELMy H-mode conditions. No damage of the capillary mesh and a good exhaust capability were observed for both metals in two separate experiments with up to 12 MW/m(2) of deposited perpendicular, inter-ELM steady-state heat flux and with ELMs of relative energy similar to 3% and a local peak energy fluence at the module similar to 15 kJ.m(-2). No droplets were directly ejected from the mesh top surface and for the LiSn experiment, no contamination of the core and SOL plasmas by Sn was observed. The elemental depth profile analysis of 14 stainless-steel samples located around the vacuum vessel for each experiment provides information about the migration of evaporated/redeposited liquid elements.

Among the innumerable remains that appear in the archaeological sites, the faunal fossil remains are one of the most numerous. Different specialities study these fossil remains of fauna from different perspectives. Among them, the quantification of the remains is some of the most important information, since they allow us to estimate what species there are and what representativeness they can have. The problem is that the archaeological sites usually consist of several bones from different species and individuals. The minimum number of individuals (MNI) is usually used to estimate the representativeness of the species (e.g. there are 4 individuals of deer and 3 individuals of horses). The problem with this technique is that it does not allow to relate the remains that appear with each individual in a concrete way. Just the DNA analysis is necessary to reassemble the remains. However, the high cost and difficulty of implementation of DNA analysis do not allow performing a genetic study. In this paper, the combination of Laser-Induced Breakdown Spectroscopy (LIBS) and Neural Networks (NN) has been successfully implemented to discriminate and reassemble wild deer bones from different individuals. This is a step further from human bones classification and one step behind the archaeological bones classification. The elemental composition of bones provides enough information to get the correct discrimination of different individuals. The spectral correlation has exceeded 93 %. There have been no false positives and negatives. Also, the quantification of the different inorganic elements present in all bone samples has been achieved by the Calibration-Free LIBS (CF-LIBS) approach. Both approaches are different, NN is more qualitative and CF-LIBS, quantitative. Usually, chemometric methods are employed for the discrimination of samples, but it is an approach that requires a lot of LIBS spectra in order to perform the training, validation and test. In the case of CF-LIBS, only one spectrum with a certain degree of accumulation is necessary to obtain the elemental concentration. Thus, both approaches have been explored in this work. This fast analysis could allow archaeologist to perform a correct classification of individuals without performing several DNA´s analysis. This would save time and resources.

Introduction/setting the scene 1 Water-resource issues in the United States and the changing focus on groundwater A. Stone 2 The challenges of municipal groundwater supply from private land H. Seyler, A. Mlisa & K. Riemann 3 When are groundwater data enough for decision-making? J.J.P. Vivier & I.J. Van Der Walt 4 Development of emergency water supplies for the drought-impacted southern Cape coastal region of South Africa - observations while abstracting saline water for desalination R. Parsons 5 Guidelines for integrated catchment monitoring: ICM mind-map development and example of application N. Jovanovic, S. Israel, C. Petersen, R.D.H. Bugan, G. Tredoux, W.P. de Clercq, R. Rose, J. Conrad & M. Demlie 6 Socio-economic aspects of groundwater demand: Franschhoek case study D. Pearce, Y. Xu, E. Makaudze & L. Brendonck 7 Using numerical modelling to cope with uncertainty in the real world: Examples from various models in the Western Cape H. Seyler & E.R. Hay 8 Numerical modelling techniques for fractured aquifers and flooding of mines K.T. Witthuser & C.M. Konig 9 Assessing uncertainties in surface-water and groundwater interaction modelling - a case study from South Africa using the Pitman model J.L. Tanner & D.A. Hughes 10 Groundwater extractions in Flanders - an enforcement review (2005-2009) J. November, R. Baert & M. Blondeel 11 The impact of climate transitions on the radionuclide transport through a sedimentary aquifer J. Flugge, M. Stockmann, A. Schneider & U. Noseck 12 Identification and management of strategic groundwater bodies for emergency situations in Bratislava District, Slovak Republic J. Michalko, J. Kordik, D. Bodis, P. Malik, R. Cernak, F. Bottlik, P. Veis & Z. Grolmusova 13 A model of long-term catchment-scale nitrate transport in a UK Chalk catchment N.J.K. Howden, S.A. Mathias, M.J. Whelan, T.P. Burt & F. Worrall 14 Hydrogeological study for sustainable water-resource exploitation - Ibo Island, Mozambique E. Vilanova, E. Docampo, C. Mecerreyes & J. Molinero 15 In situ nitrate removal from groundwater using freely available carbon material at an industrially polluted site S. Israel, A. Rosenov, G. Tredoux & N. Jovanovic 16 Classification of surface-water - groundwater interaction of the Mokolo and Lephalala River systems in the Limpopo WMA T.G. Rossouw, M. Holland & N. Motebe 17 Is the Precambrian basement aquifer in Malawi up to the job? J. Davies, J.L. Farr & N.S. Robins 18 Preliminary assessment of water-supply availability with regard to potential shale-gas development in the Karoo region of South Africa P.D. Vermeulen 19 Compiling the South African Development Community Hydrogeological Map and Atlas: Opportunities for the future K. Pietersen, N. Kellgren & M. Roos

Molybdenum and its alloys have been chosen as substrate and support material for tungsten thin layers at special limiters and divertors parts of tokamak devices. These Molybdenum parts of the tokamak walls are used for mapping and quantification of material migration and redeposition. In this work, we used Laser Induced Breakdown Spectroscopy (LIBS) as a diagnostic method to analyse Mo-Zr-Ti alloy (TZM) under three different ambient conditions expected in a tokamak in between periods of plasma operation. LIBS spectra were measured under air atmosphere and under Argon and Nitrogen flow at the laser spot on the sample. The resulting plasma plume was created using Nd:YAG (1064 nm) laser operating at the fourth harmonic frequency (266 nm). Atomic and ionic spectral lines of Mo, Ti and Zr were selected from spectra and used for analysis. The evolution of plasma parameters – electron density (ne) and electron temperature (Te) - has been observed by choosing different gate windows and delays relative to the laser pulse. Finally, the elemental concentration of the TZM sample has been calculated by the calibration free LIBS approach. The results are showing that most suitable conditions for elemental analysis are gate delay and gate width equal to 750, 1000, 1500 ns respectively, where we observed similar elementary concentrations in all three conditions.

The Kosice meteorite was observed to fall on 28 February 2010 at 23:25 UT near the city of Kosice in eastern Slovakia and its mineralogy, petrology, and geochemistry are described. The characteristic features of the meteorite fragments are fan-like, mosaic, lamellar, and granular chondrules, which were up to 1.2 mm in diameter. The fusion crust has a black-gray color with a thickness up to 0.6 mm. The matrix of the meteorite is formed mainly by forsterite (Fo80.6); diopside; enstatite (Fs16.7); albite; troilite; Fe-Ni metals such as iron and taenite; and some augite, chlorapatite, merrillite, chromite, and tetrataenite. Plagioclase-like glass was also identified. Relative uniform chemical composition of basic silicates, partially brecciated textures, as well as skeletal taenite crystals into troilite veinlets suggest monomict breccia formed at conditions of rapid cooling. The Kosice meteorite is classified as ordinary chondrite of the H5 type which has been slightly weathered, and only short veinlets of Fe hydroxides are present. The textural relationships indicate an S3 degree of shock metamorphism and W0 weathering grade. Some fragments of the meteorite Kosice are formed by monomict breccia of the petrological type H5. On the basis of REE content, we suggest the Kosice chondrite is probably from the same parent body as H5 chondrite Moravka from Czech Republic. Electron-microprobe analysis (EMPA) with focused and defocused electron beam, whole-rock analysis (WRA), inductively coupled plasma mass and optical emission spectroscopy (ICP MS, ICP OES), and calibration-free laser induced breakdown spectroscopy (CF-LIBS) were used to characterize the Kosice fragments. The results provide further evidence that whole-rock analysis gives the most accurate analyses, but this method is completely destructive. Two other proposed methods are partially destructive (EMPA) or nondestructive (CF-LIBS), but only major and minor elements can be evaluated due to the significantly lower sample consumption.

In this review, we present person-transportable laser induced breakdown spectroscopy (LIBS) devices that have previously been developed and reported in the literature as well as their applications. They are compared with X-ray fluorescent (XRF) devices, which represent their strongest competition. Although LIBS devices have advantages over XRF devices, such as sensitivity to the light elements, high spatial resolution and the possibility to distinguish between different layers of the sample, there are also disadvantages and both are discussed here. Furthermore, the essential portable LIBS instrumentation (laser, spectrograph and detector) is presented, and published results related to new laser sources (diode-pumped solid-state, microchip and fiber lasers) used in LIBS are overviewed. Compared to conventional compact flashlamp pumped solid-state lasers, the new laser sources provide higher repetition rates, higher efficiency (less power consumption) and higher beam quality, resulting in higher fluences, even for lower energies, and could potentially increase the figure of merit of portable LIBS instruments. Compact spectrometers used in portable LIBS devices and their parts (spectrograph, detector) are also discussed.

Stable isotope composition of human fingernails has proven to be useful for documenting human dietary information and geographical patterns in archeological, forensic, anthropological and biological studies. Therefore, it is of interest to detect all factors influencing the stable isotopic composition in the certain regions in the world. Carbon and nitrogen isotope data of human fingernail keratin from 52 individuals from Slovakia were reported in this study. The online combustion and continuous flow isotope-ratio mass spectrometer Delta V Advantage was used for δ(13)C and δ(15)N analysis of fingernail keratin samples from 24 vegetarian and 28 omnivorous individuals. A group of people with frequent meat consumption showed enrichment in (13)C and (15)N isotopes in fingernails. A similar trend was observed with increasing seafood in an individual's diet. Moreover a significant difference was revealed between smokers and nonsmokers for both δ(13)C and δ(15)N values. These data were compared to previously published δ(13)C and δ(15)N fingernail values from across the globe. This study brings new information on the stable isotope signature of individuals from Slovakia and characterizes the Central European region for the first time. The stable isotope composition of fingernails is influenced by the frequency of meat and seafood consumption as well as smoking.

A spectroscopic study of ammonia molecule in the 2.3 μm water atmospheric window is presented. Compared to previous experimental works a narrow, broadly tunable, continuous laser source was applied in order to obtain high resolution spectra in this range. It was the first application of the newly developed Vertical External Cavity Surface Emitting Laser (VECSEL). The analysis of the absorption spectra of two different isotopologue admixtures allowed to identify 336 14NH3 and 244 15NH3 lines in the studied region from 4275 to 4340 cm−1. These data were compared to previous line list based on experimental data – the HITRAN database and the work of Urban et al., as well as to the theoretical predictions by Yurchenko et al. and Huang et al. Together for 235 14NH3 and 183 15NH3 lines a complete assignment was proposed. From those 63 14NH3 and 114 15NH3 transitions were newly assigned. The complete peaklist of transitions containing ro-vibrational state identifications is presented in Supplementary materials.

In this paper, the potential application of a calibration-free laser-induced breakdown spectroscopy (CF-LIBS) method for the determination of the silicon-to-aluminum molar ratio in microporous zeolites (with both intermediate and high silica contents) is discussed. Three different zeolite types, i.e., mordenite and zeolites type Y and ZSM-5, were analyzed in this study and were shown to have Si/Al molar ratios in the range between 2.3 and 51.8. Many ionic and neutral atomic spectral lines of silicon and aluminum were detected in the measured LIBS spectra in the spectral range 200–1000 nm, but not all of the observed spectral lines are convenient for a CF-LIBS analysis. To increase the accuracy of the results, only lines with no or low self-absorption probability were selected. A systematic method is proposed to select spectral lines based on three main parameters: the transition probability (Einstein coefficient), the lower level energy of the observed transition and the number density ratio between singly ionized and neutral species (as calculated for Si and Al for the measured electron density and electron temperature). The calculated Si/Al molar ratios were close to that determined by wet chemical analysis with an average relative standard deviation of approximately 5% (maximum less than 15%). Our results point to the possibility of using CF-LIBS for analysis of these types of materials and for determination of Si/Al molar ratios.

The difference between the composition of the surface and the inner part of the LiSn sample was studied using Calibration Free Laser Induced Breakdown Spectroscopy (CF-LIBS) method. The sample was analysed under the low pressure (1330 Pa) in Ar atmosphere. The spectra were record using Echelle spectrometer (Mechelle ME5000). Gate delay and gate width was optimised and set to 300 ns . In order to analyse depth profile the LIBS spectra was recorded after each laser shot. The electron density analysed by laser induced plasma was determined separately for each laser shot, which means for each ablated layer of investigated sample. The difference between the individual shots taken at distinct sites of the sample are shown. The CF-LIBS method was used to determine the elemental composition near the surface and in the central part of the LiSn sample.

ITER plans foresee the quantitative diagnostics of fuel retention in reactor walls at near-atmospheric pressures. Using laser induced breakdown spectroscopy (LIBS) for this purpose assumes a reliable resolving of Balmer α-lines of hydrogen isotopes in spectra of plasma produced by focused laser radiation onto the target surface. To develop LIBS for quantitative diagnostics of fuel retention during the maintenance breaks of ITER, the effect of background gas pressure on the laser-induced plasma characteristics has been studied. The background pressure limits the expansion rate of plasma and as a result it leads to higher plasma concentrations. At the same time the limiting factor of the resolving of hydrogen isotope lines is the lines broadening by Stark effect, which is the function of electron concentration. The resolving of lines become possible recording spectra at longer delay times after the laser pulse. On the other hand, at longer delays the signal-to-noise ratio decreases. As a compromise, we found that at atmospheric pressure and at delay times >2000 ns, a fitting of Hα and Dα lines by Voigt contours allows a reliable discrimination of these lines. © 2017 University of Tartu.

Laser-induced breakdown spectroscopy (LIBS) has been applied to classify French wines according to their production regions. The use of the surface-assisted (or surface-enhanced) sample preparation method enabled a sub-ppm limit of detection (LOD), which led to the detection and identification of at least 22 metal and nonmetal elements in a typical wine sample including majors, minors and traces. An ensemble of 29 bottles of French wines, either red or white wines, from five production regions, Alsace, Bourgogne, Beaujolais, Bordeaux and Languedoc, was analyzed together with a wine from California, considered as an outlier. A non-supervised classification model based on principal component analysis (PCA) was first developed for the classification. The results showed a limited separation power of the model, which however allowed, in a step by step approach, to understand the physical reasons behind each step of sample separation and especially to observe the influence of the matrix effect in the sample classification. A supervised classification model was then developed based on random forest (RF), which is in addition a nonlinear algorithm. The obtained classification results were satisfactory with, when the parameters of the model were optimized, a classification accuracy of 100% for the tested samples. We especially discuss in the paper, the effect of spectrum normalization with an internal reference, the choice of input variables for the classification models and the optimization of parameters for the developed classification models.

International audience; A 13.56 MHz RF discharge in hydrogen was studied within the pressure range of 1-17 10 Pa, and at power range of 400-1000 W. The electron energy distribution function and 18 electron density were measured by a Langmuir probe. The gas temperature was determined by 19 the Fulcher-α system in pure H2, and by the second positive system of nitrogen using N2 as the 20 probing gas. The gas temperature was constant and equal to 450 ± 50 K in the Capacitively 21 Coupled Plasma mode (CCP), and it was increasing with pressure and power in the Inductively 22 Coupled Plasma mode (ICP). Also the vibrational temperature of ground state of hydrogen 23 molecules was determined to be around 3100 and 2000 ± 500 K in ICP and CCP mode, 24 respectively. The concentration of atomic hydrogen was determined by means of actinometry, 25 either by using Ar (5 %) as the probing gas, or by using H2 as the actinometer in pure hydrogen 26 (Q1 rotational line of Fulcher-α system) The concentration of hydrogen density was increasing 27 with pressure in both modes, but with a dissociation degree slightly higher in the ICP mode (a 28 factor 2). 29 30 Submitted to Physica Scripta 31

Laser induced breakdown spectroscopy was used for calibration analysis of different types of microporous crystalline aluminosilicates with exactly ordered structure — zeolites. The LIBS plasma was generated using a Q-switched Nd:YAG laser operating at the wavelength of 532 nm and providing laser pulses of 4 ns duration. Plasma emission was analysed by echelle type emission spectrometer, providing wide spectral range 200–950 nm. The spectrometer was equipped with intensified CCD camera providing rapid spectral acquisition (gating time from 5 ns). The optimum experimental conditions (time delay, gate width and laser pulse energy) have been determined for reliable use of LIBS for quantitative analysis. Samples of different molar ratios of Si/Al were used to create the calibration curves. Calibration curves for different types of zeolites (mordenite, type Y and ZSM-5) were constructed. Molar ratios of Si/Al for samples used for calibration were determined by classical wet chemical analysis and were in the range 5.3–51.8 for mordenite, 2.3–12.8 for type Y and 14–600 for ZSM-5. Zeolites with these molar ratios of Si/Al are usually used as catalysts in alkylation reactions. Laser induced breakdown spectroscopy is a suitable method for analysis of molar ratio Si/Al in zeolites, because it is simple, fast, and does not require sample preparation compared with classical wet chemical analysis which are time consuming, require difficult sample preparation and manipulation with strong acids and bases.

Measurements of surface loss probabilities of oxygen atoms on Simax glass, PET, Teflon, and Mica at room temperature are presented. The surface loss probability was measured by using a stationary afterglow double pulse discharge technique. The main discharge pulse created oxygen atoms by dissociation of O 2 molecules. The second (probe) discharge pulse excited existing atoms in the afterglow. The decay of the density of the oxygen atoms in volume was monitored by discharge induced emission spectroscopy of O lines and Ar actinometric lines. The rate of decay of oxygen atoms was used to determine their surface loss probability. The determined surface loss probabilities are: Simax (3.9 ± 0.65) × 10 −3 , PET (9.3 ± 1.3) × 10 −4 , Teflon (6.6 ± 1.3) × 10 −4 , and Mica (1.2 ± 0.3) × 10 −3 .

This work studies the ability of laser-induced breakdown spectroscopy (LIBS) to improve the detection of light elements such as silicon (Si), boron (B), carbon (C), and sulfur (S). In this study, the plasma decay over time was simulated using the LIBS application provided by NIST, obtaining spectra in the spectral range ranging from the vacuum ultraviolet (VUV) to the near infrared (NIR) region. Since the electron density (n e) and plasma temperature (T e) decrease during the decaying process, the intensities of emission lines from neutral, singly ionized, and doubly ionized species were calculated. The results allowed us to determine the range of suitable n e and T e for experimental measurements, and to construct a Saha–Boltzmann (SB) plot using neutral, singly ionized, and doubly ionized species. Samples containing Si, B, C, and S were measured at delays of 100–1000 ns after the laser shot at low pressure (13 mbar) in a helium atmosphere. From the measured data, suitable lines were chosen in the VUV range to calculate the T e of plasma for each sample at different delays. The results demonstrate that due to the inclusion of multiple species across VUV–UV–NIR, an appreciable improvement in the accuracy of T e was obtained, which is an essential factor for calibration-free LIBS (CF-LIBS).

This study presents the first application of the N2 Herman-infrared (HIR) ro-vibrational model for the metrology of the atmospheric-pressure dielectric-barrier discharge. Our recent findings of suitable conditions for observation of the unperturbed HIR system (Annusova et al Contrib. Plasma Phys. 2017) gave us the opportunity to develop and test a numerical representation of this complex system composed of 75 branches. Commonly, the HIR covers a part of the near infrared spectra (690–850 nm) with its bands mixed with the N2 first positive system (1PS), which hinders applications of these systems for optical metrology of the discharge. In this work, we present a complex ro-vibrational model of the 1PS and HIR systems, which allowed us to untangle their spectra and retrieve the rotational temperature and vibrational populations of the systems for the first time. The latter was achieved by coupling the PGHOPHER simulation package with molecular constants obtained from high-resolution experiments. To test the model, the results and precision were compared to the retrievals based on the models of the NO γ and N2 second positive systems using the LIFBASE and SPECAIR programs, respectively.

Laser-induced breakdown spectroscopy (LIBS) in the vacuum ultraviolet range (VUV, λ < 200 nm) is employed for the detection of trace elements in polyethylene (PE) that are difficult to detect in the UV/VIS range. For effective laser ablation of PE, we use a F2 laser (wavelength λ = 157 nm) with a laser pulse length of 20 ns, a pulse energy up to 50 mJ, and pulse repetition rate of 10 Hz. The optical radiation of the laser-induced plasma is measured by a VUV spectrometer with detection range down to λ = 115 nm. A gated photon-counting system is used to acquire time-resolved spectra. From LIBS measurements of certified polymer reference materials, we obtained a limit of detection (LOD) of 50 µg/g for sulphur and 215 µg/g for zinc, respectively. The VUV LIBS spectra of PE are dominated by strong emission lines of neutral and ionized carbon atoms. From time-resolved measurements of the carbon line intensities, we determine the temporal evolution of the electronic plasma temperature, Te. For this, we use Saha–Boltzmann plots with the electron density in the plasma, Ne, derived from the broadening of the hydrogen H-α line. With the parameters Te and Ne, we calculate the intensity ratio of the atomic sulphur and carbon lines at 180.7 nm and at 175.2 nm, respectively. The calculated intensity ratios are in good agreement with the experimentally measured results.

Optical emission spectroscopy (OES) is used as the main experimental tool for comparison with simulations of the plasma and gas phase composition during plasma-enhanced hot filament catalytic chemical vapor deposition (PE HF CCVD) growth of carbon nanotubes (CNTs). Calculated concentration of more than 45 species in model of the CVD reactor is acquired by Chemkin™ software. Study of different conditions is performed and a close relationship can be found between the nature and the growth rate of carbon nanostructures and the concentration of the active gas phase species. Moreover it is shown that significant changes in the density and morphology of the CNTs grown in the presence of NH 3 could be mainly explained by the gas phase formation of CN and HCN.

The absorption spectrum of the (1–0) band of the b 1 Σ g + ← a 1 Δ g Noxon system near 1505 nm has been recorded by cw-CRDS in afterglow of a microwave discharge. The details of this method are presented along with spectroscopic data of 29 recorded lines of which 21 have been observed for the first time. The measured line positions are compared with positions calculated from rotational constants available in the literature. The density and the temperature of the generated singlet molecular oxygen O 2 ( a 1 Δ g ) are presented.

To support experimental investigations, a model based on Chemkin™ software was used to simulate gas phase and surface chemistry during plasma-enhanced catalytic CVD of carbon nanotubes. According to these calculations, gas phase composition, etching process and growth rates are calculated. The role of several carbon species, hydrocarbon molecules and ions in the growth mechanism of carbon nanotubes is presented in this study. Study of different conditions of gas phase activation sources and pressure is performed.

Growth of carbon nanofibers and nanotubes by combination of aerosol synthesis and plasma-enhanced catalytic chemical vapor deposition with alcohol as carbon precursor is presented. Only a hollow cathode glow discharge (HCGD) is used as gas activation process without any specific heating of the substrate. Specially designed hollow cathode enables the evaporation of catalyst directly on the substrate for catalytic growth. Product of physical vapor deposition process was examined by energy dispersive X-ray spectrometer (EDS). Spectroscopic features of the plasma were monitored by optical emission spectroscopy (OES). Carbon deposition was examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Catalytic nanofibers and multi-walled carbon nanotubes with outer diameters 20–60 nm have been observed.