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The vacuum UV (VUV)-near Infrared (NIR) laser induced breakdown spectroscopy (LIBS) technique was applied to investigate the composition of W-based samples with a protective carbon layer. The sample was analyzed under pressures from 5 to 105 Pa and atmosphere (air, He). The spectra were recorded with three spectrometers at delays from 200 ns to 10 μs at atmospheric pressures and from 100 to 500 ns at low pressures. The electron density was determined from the measured spectra using Stark broadening and the electron temperature from the W I-W III Saha-plot in the VUV-NIR spectral range. The better precision was achieved due to usage W III spectral lines of tungsten. The achieved results are more reliable than results obtained without W III spectral lines. The calibration free LIBS method was then applied to determine the W and C contents of the analyzed sample.

The BH A 1Π → X 1Σ+ (0–0) transition was studied, in the emission mode, for gas temperature determination. Two typical conditions were used: doped diamond deposition conditions (H2/CH4/B2H6 99%:1%:0–100 ppm, from 2500 to 7550 Pa) and the vessel cleaning condition (H2, 85 Pa). Among the P, Q and R branches of the A 1Π → X 1Σ+ (0–0) transition, only the unresolved Q branch is clearly observed in emission mode under the doped diamond deposition conditions, whereas the full rotational structure is observed under the vessel cleaning condition. We developed a simple simulation model based on calculation of the position of the rotational lines and the line intensities as a function of the temperature and profile width. After validation of the model using the R resolved structure from our data and from other authors' data, we applied this attractive method to a quick temperature determination in the unresolved Q branch simulation. The calculated temperatures were compared to other well established results obtained under the same conditions. Kinetics considerations led to the conclusion that the rotational temperature of the A excited states accounts for the gas temperature in both the above-mentioned conditions. It is also shown that two distinct rotational populations are present, suggesting the existence of two excitation mechanisms.

The surface recombination probability of oxygen atoms as a function of wall temperature is studied by using a double pulse discharge technique. The main discharge pulse dissociates molecular oxygen and the second pulse, shorter than the main one, excites atoms during the stationary afterglow. The recombination probability is determined from the atomic oxygen density decay during the stationary afterglow of the main pulse (MP). The oxygen atoms are detected by time-resolved optical emission spectroscopy. In order to correlate the oxygen emission lines with the oxygen atom density, argon is used as an actinometer. To scan the whole afterglow of the main discharge pulse, the delay of the probe pulse is uniformly increased in every period following the MP. The evolution of the relative O atom density is deduced from the O emission lines at 777 and 844?nm and from the Ar actinometry line at 750?nm. The wall recombination probability ? on a Pyrex surface ranges from 4.0 ? 10?4 to 1.6 ? 10?2 for wall temperatures from 77 to 460?K.

Poly(3-dodecylthiophene) (P3DDT), with different amounts of head-to-head configuration defects, was characterized by ultraviolet–visible, 1H-NMR, photoluminescence, and Raman spectra. The heat-induced conformational sample changes were studied by electron paramagnetic resonance (EPR). For the study of these changes, a spin-probe technique was used, in which 5-doxyl-stearic acid methyl ester was applied as a spin probe. From the EPR spin-probe spectra, rotational correlation times and order parameters were calculated. The heat-induced conformational changes of P3DDT were accompanied by a monotonic decrease in the rotational correlation time up to approximately −33°C (240 K) and then by an increase in the range of the glass-transition temperatures, with the maximum being near room temperature and depending on the effective conjugation length. Afterward, the rotational correlation times had a decreasing tendency up to 90°C (363 K). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2215–2223, 2003

The method of chemical oxidative polymerization with FeCl 3 was used to synthesize the copolymer of dipyrido-[3,2-a; 2′,3′-c]-thien-[3,4-c]azine (DPTA) and 3-dodecylthiophene (DDT). The copolymer was characterized by UV–VIS, Raman, 1 H and 13 C NMR and EPR spectroscopy. It has been found that the DPTA/DDT copolymer exhibits properties of the low-band-gap polymer ( E g

The study of the vibrational state population of the O2(b1Σ g + ) metastable state in a pure oxygen DC pulsed discharge is presented. The vibrational temperature is evaluated from the relative populations of v = 0, 1 and 2 states. The populations are determined from the intensities of (0-0), (1-1), (1-0) and (2-1) transitions of the atmospheric system. The most intensive (0-0) and (1-1) bands are used in the time-resolved measurements in order to determine the time evolution of the vibrational temperature during the discharge pulse.

Oxygen atoms recombination at the wall is studied by time-resolved Optical Emission Spectroscopy in a pulsed discharge. In order to observe the atomic oxygen emission after discharge pulse, it is indispensable to re-excite O atoms because the lifetime of O* atoms is short. Here is proposed a technique based on a double pulse excitation. Atomic oxygen, created during the main discharge pulse, is probed in a time after-glow with a diagnostic pulse. This diagnostic pulse is as short as possible to only repopulate the atomic excited states, without significant production of supplementary atoms. The intensities of the emission lines O(3P-3S) at 844.6 nm and O(5P-5S) at 777.4 nm, measured during diagnostic pulse, are observed in the whole time after-glow as a function of delay after main pulse. The decrease of line intensities is related to the recombination of O atoms at the wall. For a “Pyrex” wall at 300 K, the obtained recombination probability γ is 10−3. This value is in agreement with previous results.

Optical emission spectroscopy, ranging from visible to near infrared, is used to determine densities and rotational temperatures of N2(B?3?g) and N2(C?3?u) states in a nitrogen?argon (0?95% Ar) discharge, under moderate pressures (200?400?Pa). The plasma is sustained by a helical cavity with an excitation frequency of 27?MHz and power fixed to 28?W. Firstly, in the case of a pure N2 discharge, the two states turn out to have a similar rotational temperature, which approximates the gas temperature reasonably well. With a gradual increase in the Ar concentration up to 95%, the rotational temperature of N2(C?3?u) roughly doubles while that of N2(B?3?g) stays unchanged at 430???50?K regardless of the gas composition. Secondly, as observed, the densities of the N2(B?3?g) and N2(C?3?u) states increase with increasing Ar percentage in the gas mixture. The increase in the emission intensity values is less marked for positions corresponding to both ends of the cavity. In fact, the difference in the emission level between the power input and helix middle positions is reduced, revealing that the total discharge is more uniform along the cavity for large argon concentrations. The experimental results show a strong dependence of temperatures and densities on the Ar amount in the gas mixture. A kinetic model is developed to explain this phenomenon, which is then used in modelling density evolutions versus relative abundance of Ar and versus the position along the cavity axis. The model indicates the importance of the role of electron and metastable species in the above-described discharge.

9 pages; International audience; This paper illustrates the potentialities of a home-made portable LIBS (laser-induced breakdown spectroscopy) instrument in Earth sciences, more particularly in geochemically recognizing (i) tephra layers in lacustrine sediments and (ii) fossilization processes in ammonites. Abundances for selected lines of Al, Ca, Fe, Ti, Ba and Na were determined in lacustrine chalk sediments of the Jura, where the Laacher See Tephra (LST) layer is recorded. A statistical treatment of elemental maps produced from the section of a sedimentary column containing the LST event allows instrumental conditions to be optimized. Accumulating spectra from close shot positions gives better results than multiplying shots at the same location. A depth profile method was applied to study ammonite fossilization (pyritization, phosphatization) processes. Depth variations of Fe, Ca, Al intensities, and Fe/Ca and Al/Ca ratios provide indications about pyritization, but phosphatization processes cannot be determined with our device.

The quenching rates of N2(a1 Pi g, v'=3-6) by molecular nitrogen are measured in the time afterglow of a pulsed low-pressure nitrogen discharge. The following quenching rate coefficients were estimated: KQ(3)=(3.42+or-0.3)*10-11 cm3 s-1, KQ(4)=(9.16+or-0.9)*10-11 cm3 s-1, KQ(5)=(15.3+or-1.3)*10-11 cm3 s-1 and KQ(6) approximately=22*10-11 cm3 s-1 for v'=3-6 respectively.

Optical emission spectroscopy in vacuum ultraviolet and UV spectral ranges is applied to study densities, and vibrational and rotational temperatures of the N2 molecule in a nitrogen–argon (0–95% Ar) plasma sustained at a pressure of 400 Pa by a helical cavity supplied with a power of 28 W and an excitation frequency of 27 MHz. The spatial investigation of all emission systems from UV to NIR shows a minimum situated in the middle of the helical structure and two maxima located at the positions where the RF power is transmitted to the gas and at the end of the helix. The minimum was deepest for emission of the first positive (1+) nitrogen system. This hollow shaped density profile due to the presence of a non-linear phenomenon in the discharge is constant whatever the gas composition. The emissions related to Lyman–Birge–Hopfield and the second positive (2+) systems of molecular nitrogen, and N(2P) atoms, are analyzed versus the Ar percentage. Additionally, the NO(A 2Σ+ → X 2Π) and OH(A 2Σ+ → X 2Π) emission systems coming from impurities are investigated. All the densities of the considered species increase with Ar amount. The rotational and vibrational temperatures of the emitter species are determined through the comparison between experimental and simulated spectra. In the case of a N2 discharge, all the rotational temperatures deduced through the nitrogen emission systems are equal and can be assimilated to the gas temperature. With the increase in the Ar amount, only the rotational temperature obtained from the 1+ system is close to the gas temperature. The rotational and vibrational temperatures related to the NO(A 2Σ+) species are constant whatever the gas composition. The vibrational distribution function of N2(a 1Πg) state presents a Boltzmann law with a vibrational temperature in the range 5600–8000 K (±1000 K) for the N2–x% Ar mixture with x < 75%. When the Ar percentage increases above this limit, we observe strong deviations from the Boltzmann law and no temperature can be deduced. Some kinetic considerations, where the nitrogen and argon metastables play an important role, are discussed to explain the strong dependence of the temperatures and density species toward the Ar amount in the gas mixture.

The relaxation rate of N2(a1 Pi g, v'=0-2) singlet metastable state is observed from the emission of a1 Pi g-X1 Sigma g+ bands in a nitrogen time afterglow. The quenching rates k0=0.91+or-0.05, k1=1.64+or-0.048 and k2=2.12+or-0.055 (*10-11cm3 s-1) and the radiative lifetime tau 0=54.2+or-6.5 mu s, tau 1=55.9+or-6.0 mu s and t2=54.1+or-5.8 mu s are deduced from the linear part of the dependences of the time decay against pressure.

International audience; Simulations of the gas phase chemistry (C2H2/H2) coupled with surface reactions for the catalytic growth of carbon nanostructures (nanotubes/nanofibers), using different activation modes of catalytic chemical vapor deposition (CCVD) process, are presented. Deposits issued from thermal CCVD, hot-filament CCVD, plasma- enhanced CCVD and plasma-enhanced combined with hot-filament CCVD are compared to simulations of the gas phase and surface kinetics. The influence of the activation elements is described in detail. According to these simulations taking into account optical emission spectroscopy data, gas phase composition and linear growth rate of tubular nanostructures are predicted in good agreement with the experimental observations.

Continuous wave (cw) distributed feedback (DFB) telecom diode lasers are increasingly being used as light sources in the near-IR regions of the spectrum for cavity ring-down spectroscopy (CRDS). They are compact, operate economically at room temperature, are able to generate suitable narrowband tunable coherent radiation on a single longitudinal mode and are compatible with a variety of optical components, including fibre-optic devices. The very high sensitivities enabling to measure weak absorption with cw CRDS plus the quantitative nature of the absorption measurements are enabling an expanding range of applications of cw CRDS in molecular spectroscopy, atmospheric chemistry, plasma and medical diagnosis.

Survey of several experimental techniques applied for absolute density measurements of atoms and radicals in plasma is presented. It includes the Vacuum Ultraviolet Absorption Spectroscopy, Actinometry and Emission Spectroscopy, Laser Absorption Spectroscopy and highly sensitive Cavity Ring-Down Spectroscopy. Performances and operation procedures of these techniques are illustrated.

This paper presents results from both experimental and modelling studies of a flowing afterglow in N2–O2 mixtures observed in a plasma-chemical reactor. The plasma is generated at a pressure of 440 Pa by a microwave cavity working at the excitation frequency of 433 MHz. The main nitrogen and nitrogen oxide species are experimentally studied, mainly in the late afterglow of both a N2–O2 discharge and a nitrogen discharge with a downstream O2 admixture. The molecules and relative densities were monitored by optical emission spectroscopy and the atoms by means of mass spectrometry. A temporal 0D model is built and coupled to a steady state model on and states, for comparison with the experimental results, in order to describe the kinetics of the studied afterglows. This calculation is supported by the simulation of gas flow in the reactor using COMSOL Multiphysics®. We present results concerning the temporal density evolutions of , , , , , and steady density evolutions of and species as functions of the amount and location of an oxygen injection. The principal mechanisms in the described system are identified allowing the proposal of a simplified kinetic scheme showing a strong coupling among , and the main channels of the formation and destruction of NO, NO2 and O3 molecules.

Calibration-free laser induced breakdown spectroscopy (CF-LIBS) was used for the determination of elemental composition and quantitative analysis of the Kosice meteorite by means of time resolved and broadband emission spectroscopy (200–1000 nm). The electron temperature was determined using the Saha-Boltzmann plot method and the electron density from Stark broadening of the hydrogen H α line (656 nm). Apart from magnesium, silicon and iron, which are the main elemental constituents of examined meteorite fragments, elements such as aluminum, nickel, potassium, sodium, chromium, calcium and manganese were also identified in the obtained LIBS spectra. Concentrations of Al, Ca, Cr, Fe, Mg, Mn, Na, Ni and Si were calculated using the calibration free approach and results were compared with ones obtained from the ICP-MS analyses. For the increase of the CF-LIBS accuracy, a selection of spectral lines was performed. Considering the transition probability, the population of absorbing level, the degree of ionization and predicted elemental concentration we calculated the probability of self-absorption and, consequently, spectral lines with highest self-absorption probability were rejected. CF-LIBS can be used as an alternative method for the meteorite fragments analysis (including the inner part and crust), because this method is quasi non-destructive and therefore analysis of all found fragments with minimal destruction is possible.

Laser induced breakdown spectroscopy (LIBS) is an elemental analytical technique with various applications. The paper demonstrates the first LIBS measurements of human liver samples for the purpose of detecting the higher copper content related with the advanced stage of Wilson’s disease. These measurements were implemented using a Nd:YAG laser working at the wavelength of 532 nm and an echelle type spectrometer equipped with an intensified CCD camera allowing for a wide spectral range coverage (200–950 nm) and rapid camera gating (minimum gating time of 5 ns). Seven liver samples with suspected Wilson’s disease and five reference samples were investigated. The main parameter of interest was the Cu/C ratio obtained at first from spectra and secondly directly from an iCCD image. Our experiment is a pilot study, which shows LIBS analysis of human liver samples for the purpose of detecting the normal and higher copper content for the first time. The method proved to be a quick and a low-cost approach for the detection of pathological accumulation of copper in the affected tissue.

Continuous wave cavity ring-down spectroscopy using an electronically switched telecom distributed feedback laser module is demonstrated. By adding a compensation waveform current to the step-function switched laser current the laser wavelength stabilisation time is reduced to about 4 ms corresponding to a 200 Hz utmost ring-down transient repetition rate.

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Standard H2∕CH4∕B2H6 plasmas (99% of H2 and 1% of CH4, with 0–100ppm of B2H6 added) used for doped diamond film growth are studied by optical emission spectroscopy in order to gain a better understanding of the influence of boron species on the gas phase chemistry. Only two boron species are detected under our experimental conditions (9∕15∕23Wcm−3 average microwave power density values), and the emission spectra used for studies reported here are B(S1∕22−P1∕2,3∕202) and BH[AΠ1‐XΣ+1(0,0)]. Variations of their respective emission intensities as a function of the ratio B∕C, the boron to carbon ratio in the gas mixture, are reported. We confirmed that the plasma parameters (Tg, Te, and ne) are not affected by the introduction of diborane, and the number densities of B atoms and BH radical species were estimated from experimental measurements. The results are compared to those obtained from a zero-dimensional chemical kinetic model where two groups of reactions are considered: (1) BHx+H↔BHx−1+H2 (x=1–3) by ana...

Analysis of acid pitchstone (sample from Iceland) using laser induced breakdown spectroscopy (LIBS) is presented in this study. The rock sample was taken because of its uniform composition and a homogenous structure at microscale. Elements like Si, Fe, Ca, Mg, Al, Mn, Ti, Na, K, Ba, Sr and Li were detected in the LIBS spectra. Important plasma parameters (electron density and temperature) were calculated on the base of Stark broadening mechanism of spectral lines and Saha- Boltzmann plot method, respectively. Quantitative analysis was performed using calibration free (CF) approach of LIBS method. CF-LIBS analysis compared to reconstructed bulk rock analysis using precise mineral and glass analyses obtained by electron microprobe analysis (EMPA) gives a good correlation, sufficient enough for having primary information of chemical composition of the studied rock sample or alternatively large mineral phases. An element with very low atomic number, lithium, was detected only by LIBS. Li is not detectable on microprobe. Taking into account possible local mineral accumulations and imprecisions induced by estimation of mineral volumes in the glass the CF-LIBS method gives acceptably precise analyses for geological purposes.

For ITER and other future fusion devices, tungsten (W) and its alloys are primary candidates for the first wall in divertor, and molybdenum (Mo) will be used as the background material for erosion mapping and thickness control of the deposited layers and mirror materials. Considering the advantage of on-line analysis, laser-induced breakdown spectroscopy (LIBS) is being considered as the most promising tool to be used at ITER for the monitoring of the erosion and deposition processes and the fuel retention at the first wall. In this paper, picosecond (∼30 ps) and nanosecond (8 ns) time-resolved LIBS spectra were recorded for the characterization and comparison of fusion-related high-Z pure materials (W and Mo) at atmospheric pressure in ambient air. The plasma temperature was calculated using the Boltzmann plots of both neutral and ionic species, while the electron density was evaluated from the Saha equation. In the case of ps laser pulses, lower electron temperature and density were observed. The lower temperature in the ps regime is leading to a higher neutral to ionic ratio. At shorter delay times, the difference between electron densities was smaller, but with the increased delay, the difference became significant. The obtained values of ablation rates show that the ablation rate in ps regime is approximately 4 times lower compared to the ns regime. Lower electron density, also due to the lower ablation rate in the ps regime, leads to less Stark broadening and finally narrower spectral lines in the ps regime than in the ns one. The lower energy for ps laser-plasma generation (0.3 mJ/pulse; equivalent to a fluence of 1.7 Jcm−2) allows to obtain a lower ablation rate, which leads to a better depth resolution, which is crucial for depth analysis of fusion-related materials.

No abstract, La thèse présentée porte sur les possibilités d’utilisation de la spectroscopie sur plasma induit par laser (LIBS) utilisée dans le laboratoire ainsi qu’à l’extérieur en utilisant l’appareil portable mis au point par nous et destiné pour analyser la composition élémentaire en matières. Cet appareil a été testé sur les échantillons géologiques dans l’objectif de la détection du Laacher See Tephra (LST) dans la craie lacustre enlevée dans le Jura en France. Le traitement statistique des cartes élémentaires pour les éléments Al, Ca, Fe, Ti, Ba et Na ont été effectuées à partir d’une coupe de la colonne sédimentaire contenant LST et cela a permis d’optimiser les conditions de l’expérience. La profilométrie a été utilisée sur les échantillons d’ammonites dans l’objectif de déterminer le processus de la fossilisation. La pyritisation a été considérée comme potentiellement détectable, mais l’appareil s’est révélé incapable de déterminer la phosphatation. Concernant le LIBS effectué dans le laboratoire, une réponse spectrale du spectromètre à échelle a été déterminée dans une gamme comprise entre 215 nm et 950 nm. Le modèle du rayonnement des molécules diatomiques de N2, NO et OH a été utilisé pour obtenir la source du rayonnement de référence de la décharge luminescente dans l’air. La réponse spectrale a été utilisée pour la correction des spectres mesurés dans d’autres recherches. Pour des tests sans calibration (CF-LIBS), les échantillons d’alliages d’aluminium avec de différentes compositions des éléments (Al, Mg, Mn, Si et Cu) ont été utilisés. Les résultats de l'acquisition des spectres de la localisation de 2 mm au-dessus de la surface de l’échantillon sont plus précis que ceux qui ont été acquis de la localisation de 1 mm. Une étude examinant des possibilités d’utilisation de l’auto-absorption pour analyser la concentration du magnésium dans les alliages d’aluminium est présentée dans le dernier chapitre de la thèse. A cette fin, un modèle bicouche de plasma a été utilisé et ajusté aux profiles des raies du Mg I 285,213 nm et Mg II 280,271 nm expérimentalement mesurés. Les résultats ont été comparés avec les valeurs nominales et pour la raie d’ion du Mg II 280,271 le résultat démontre une possibilité de déterminer la concentration du Mg dans l’alliage

Préparée dans le cadre d'une cotutelle entre L'UNIVERSITE DE GRENOBLE ET COMENIUS UNIVERSITY; The project of this thesis was developed as a joint supervision project between the Department of Experimental Physics at Comenius University in Bratislava and Laboratoire de Spectrometrie Physique at Joseph Fourier University in Grenoble. The aim of the project is the development and application of some of these new spectroscopic methods for the study and diagnostics of gases and plasma. In Bratislava the work under the supervision of prof. Pavel Veis and Doc. Peter Macko was oriented towards the optical diagnostics of plasma environments. Beside the principal experiments concerning the dielectric barrier discharge (DBD) and production of the singlet oxygen state, the goal was to develop spectroscopic methods capable of providing physical measurements related to this applications. In the DBD the interest was focused on the description of the excited electronic states population variations during the period of discharge. We used fast broad--band emission spectroscopy (FEBS) comprising the instrument and data treatment process to achieve this goal. In case of singlet oxygen production we developed a Cavity ring--down spectrometer (CRDS) to detect the singlet oxygen by its infrared absorption in the microwave plasma afterglow. In Grenoble under the supervision of Dr. Daniele Romanini the principal line of work consisted in the development of a new laser source - Vertical external cavity surface emitting laser (VECSEL) and its application to absorption spectroscopy. The work was held in collaboration with the Institude d'electronique du Sud in the frame of the joint ANR MIREV project. A period was also dedicated to the developing of a small, fast, robust and low-cost NO$_2$ and NO$_3$ detector based on the Incoherent broad--band cavity enhanced absorption spectroscopy (IBB--CEAS).; Le travail de thèse a été réalisé dans le cadre d'une cotutelle entre le Département de Physique Expérimental à l'Université Comenius à Bratislava et Laboratoire de Spectrométrie Physique à l'Université Joseph Fourier à Grenoble. Le but de la thèse était le développement et l'application de nouvelles méthodes spectroscopiques pour l'analyse de plasma et de gaz. A Bratislava, mon travail était supervisé par le prof. Pevel Veis et le Doc. Peter Macko . Il s'est orienté vers le diagnostique optique de plasma. Mon travail principal a été d'étudier le comportement de la décharge à barrière diélectrique(DBD) ainsi que la production d'oxygène dans l'état singulet. En parallèle, j'ai développé des méthodes de mesures des propriétés physiques liées à cette expérience. Dans le DBD, l'objectif était d'écrire l'évolution temporelle des états électroniques excités au cours de la décharge. La méthode utilisée était la spectroscopie rapide et large bande. Mon travail a consisté à mettre en place l'instrumentation ainsi que les algorithmes pour le traitement de données. Concernant l'étude de la production de l'oxygène singulet, on a développé un système CRDS (Cavity-Ring-Down Spectroscopy) capable de le détecter dans la post-décharge de plasma. A Grenoble, sous la supervision du Dr. Daniele Romanini, l'objectif principal de mon travail a consisté dans le développement d'une nouvelle source laser - Vertical External Cavity Surface Emitting Laser (VECSEL) et son application dans la spectroscopie d'absorption. Le travail a été réalisé en collaboration avec l'Institut d'électronique du Sud dans le cadre du projet ANR MIREV. En plus de ce travail, j'ai participé au développement d'un détecteur portable et bon marché pour l'analyse quantitative de NO$_2$ et NO$_3$ dans l'atmosphère par la technique Incoherent Broadband Cavity Enhanced Absorption Spectroscopy.