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Fluorescence spectroscopy is a powerful tool to obtain information on microscopicprocesses in non-equilibrium discharge plasma (corona) in dense media such as high pressuresupercritical gas and even liquids. Spectroscopic observations of the light emitted from anionization zone near a tip electrode can be used to determine structural information of thelocal environment of the emitting atoms or molecules. The spectral features observable aresensitive to the immediate surroundings of the emitting species, which makes emissionspectroscopy very useful for study of the cold nonequilibrium plasma varying the pressureand the temperature.In this work, we have studied the current-voltage characteristics and spectralcomposition of helium cryoplasma initiated with a corona discharge in gaseous and liquidhelium. A cryoplasma has been realized in laboratory conditions using corona discharge ingaseous and liquid Helium at cryogenic temperatures of the matter. Experiments were carriedout at a number of fixed temperatures from 300 K down to 4.2 K within the pressure range0.1÷10 MPa. The conditions covered a wide region of thermodynamic states of the mattersuch as from a gas with density of ~1019 cm-3 up to liquid Helium with density of 2*1022cm-3., La spectroscopie d’émission est un outil puissant pour obtenir des informations sur lesprocessus microscopiques dans un plasma de décharge hors-équilibre (décharge couronne)dans des milieux denses tels que le gaz supercritique à haute pression et les liquides. Lesobservations spectroscopiques de la lumière émise à partir d'une zone d'ionisation créée parune décharge entre une pointe fine et un plan sont utilisées pour caractériser l'environnementlocal des atomes ou des molécules émettrices. Les caractéristiques spectrales observablesétant sensibles à l'environnement immédiat de l'espèce émettrice, rend la spectroscopieoptique très utile pour l'étude du plasma hors-équilibre en fonction des paramètres du milieu(pression et température).Dans ce travail, nous avons étudié les caractéristiques courant-tension et lacomposition spectrale d’un cryoplasma initié par une décharge couronne dans l'hélium liquideet gazeux à des températures cryogéniques. Ces expériences ont été effectuées pour un certainnombre de températures fixes de 300 K à 4,2 K dans une plage de pression de 0,1 à 10 MPa.Ces conditions couvrent une large région des états thermodynamiques de la matière avec unedensité d'environ 1019 cm-3 pour le gaz à une densité de 2*1022 cm-3 pour le liquide.

The solar photon flux distribution was measured in the range from 400 to 1100 nm under a twin-span glasshouse and under the same glasshouse with blanked roof, external shading net and internal aluminized shade-screen. Measurements were also carried out under a twin-span polyethylene greenhouse, a multi-span greenhouse with fibreglass and a polyethylene tunnel. For each greenhouse configuration, the measured solar photon flux spectra were used to calculate the solar transmission for the photosynthetically active radiation waveband (PAR), from 400 to 700 nm, the near infrared waveband (NIR), from 700 to 1100 nm, and the whole waveband (TOTAL), from 400 to 1100 nm. Other parameters having a physiological interest were also determined: the broadband PAR to TOTAL photon flux ratio and PAR to NIR photon flux ratio; and the morphogenesis-related parameters, such as the red to far red photon flux ratio, the phytochrome equilibrium, the relative cycling rate, the blue to red photon flux ratio and the blue to far red photon flux ratio. The results provided a better insight on the quantitative and qualitative properties of the light environment under each greenhouse configuration. Some significant differences in the values of blue light quality related parameters were found between greenhouses. Minor changes were observed on the PAR:TOTAL and PAR:NIR photon flux ratios, but indicated that glass and blanking tend to enrich the PAR content of the transmitted light, while the two plastic cover materials have the opposite effect, enriching the NIR content. These results stressed the need for a more precise characterization of modifications in light quality induced by greenhouse materials or shading devices as plant photosynthetic and photomorphogenetic responses may be significantly influenced by these modifications.

International audience; Two surveys were carried out on ten atolls in the Tuamotu archipelago (French Polynesia, Pacific Ocean). In vitro UV (250–400 nm) spectra of water samples gave absorption at 254 nm, A254, and spectrum slope, S⋆ (computed from In Aλ versus λ).These two descriptors are negatively correlated, and data points are arrayed along a hyperbola spanned between an oceanic pole (high S⋆, low A254) and a confined pole (low 5⋆, high A254).Dissolved organic carbon (DOC) concentrations, [C], as assessed by HTCO, exhibit a narrow range (0.7–1.0 mg C.L−1 for most lagoons) contrasting with the wide diversity of optical characteristics. [C] and A254 are positively correlated, with a significant intercept (0.5 mg C.L−1) representing non-chromophoric DOC. Carbon-specific absorption, ε254 increases (from 0.4 to 1.3 m2.g−1) with increasing [C], mainly according to the literature) owing to increased average molecular weight (MW) of the chromophoric DOC fraction, which also lowers S⋆.Our optical data thus illustrate a gradient of confinement (or residence time) that corresponds to a continuum in DOC nature, especially in MW and hence in bioavailability. Optical methods are confirmed as quick and effective means of assessing DOM distribution.; Deux campagnes ont prospecté dix lagons d'atoll des Tuamotu (Polynésie française, océan Pacifique). Sur des échantillons d'eau, le spectre UV (250-400 nm) in vitro est décrit par l'absorption à 254 nm, A25,i, et la pente, S* (régression de ln:\ vs Î.). Ces deux descripteurs sont négativement corrélés. Les points s'organisent le long d'une hyperbole entre un pôle océanique (fort S*, faible A254) et un pôle confiné (faible S*, fort A254). Le carbone organique dissous (COD) présente des concentrations ([Cl. déterminées par HTCO) peu variables (0, 7-1,0 mg C.L 1), contrastant avec la large diversité des propriétés optiques. [C] et A254 ont une corrélation positive, avec une ordonnée à l'origine significative {0,5 mg c.L-') correspondant à une fraction« non chromophorique ,, du COD. L'absorption spécifique ramenée au carbone, 8254, croît (de 0,4 à 1,3 m2.g-1) pour des [Cl croissantes, surtout (d'après la littérature) en relation avec une augmen-tation du poids moléculaire moyen, qui abaisse les valeurs de S*. Nos mesures optiques décrivent ainsi un gradient de confinement (ou de temps de séjour) qui correspond à un continuum dans la nature du COD, dont son poids moléculaire et donc sa susceptibilité à une action biologique. Cette méthode rapide confirme son efficacité pour la description de la distribution de la MOD.

The use of copper emission lines for temperature measurement in plasma environments is presented. The article features the problems encountered with such a measurement method when used in a stationnary and a non-stationnary plasma. In the first case, we were concerned with the temperature measurements in the jet of a 2 MW industrial plasma torche. The plasma was stationnary and the measurement geometry allowed the use of the Abel inversion method to recover the temperature profiles in the plasma jet. The limitations of the measurement method on the jet boundaries as well as the cooling of the plasma by entrainement of cold air are discussed. In the second case, a non-stationnary plasma in a 1.4 MW electric furnace was studied. This study allowed to feature the role of the detector dynamics as related to the dynamics of the observed medium. The obtained measurements show only a probable temperature in the immediate proximity of the arc. Finally, we conclude on the validity of copper as a tracer and the use of spontaneous emission spectroscopy, an easy method to implement, compared to other sophisticated temperature measurement methods

This paper describes a numerical simulation of the behaviour of three inviscid point vortices above a flat wall. Depending on their initial positions, the trajectories of the vortices exhibit patterns ranging from regular to chaotic. The chaotic motion of vortices reulsts in high frequencies components in the wall pressure spectra. In addition, it increases the far field acoustic intensity

Using radio-frequency (r-f) sputtering, we have prepared in presence of a static magnetic field, ferromagnetic thin films of composition (Co 93 Zr 7 ) 100-y RE y (RE=Nd, Pr, Dy, Tb... a magnetic rare earth element). The study was performed for small amounts of RE substitution (0 10 kG). A low in-plane uniaxial anisotropy H k forms, wise magnitude depends upon the composition and the preparation parameters. Substitution by RE atoms affects essentially the μ frequency-response. Depending on the nature, the concentration of RE atoms and on the value of H k , a high relative rotational permeability μ (μ'-500-3000 at frequencies up to 500 MHz) was obtained. Also depending on RE and on y, high μ'' (μ''-400-3000 at v-1 GHz) distributed over a very broadfrequency range (Δv-500-2500 MHz) was measured. Using the Landau-Lifshitz equations for high frequency permeability and the values of the magnetic parameters measured by FMR, experimental spectra could be well approximated

The «beam-foil» study in the far ultraviolet region has yielded spectra of highly ionized chromium. In particular, the spectrum of Cr XV has been analysed and energy levels of the 2p 5 3l configuration have been determined with a mean accuracy of 150 cm −1 . Lifetimes of the 2p 5 3p 3 D 3 and 2p 5 3d 3 F 4 levels have been measured and the transition probabilities deduced are compared with available theoretical data Utilisation de la methode faisceau-feuille pour produire ces spectres en UV lointain. Determination des niveaux d'energie de la configuration 2p 5 3l avec une precision de l'ordre de 150 cm −1 . Deduction des probabilites des deux transitions les plus intenses a partir des durees de vie mesurees de leurs niveaux superieurs 2p 5 3p 3 D 3 et 2p 5 d 3 F 4

Une étude par distribution spectrale dans les sous-espaces définis par leur nombre de quasi-particules a été effectuée dans les isotopes pairs de plomb. La comparaison avec des résultats obtenus dans les isotopes d'étain montre que le recouvrement entre les différents sous-espaces est fortement lié à l'interaction résiduelle utilisée. En particulier des états à grand nombre de quasi-particules sont présents à basse énergie. Le problème des états spurieux inhérent à cette méthode, qui sont responsables d'une surestimation du couplage, est abordé et différentes corrections sont proposées aussi bien sur les dimensions, les centroïdes et les largeurs des sous-espaces.

International audience; (Signal-shape processing in analytical chemistry.) When signal evolution (e.g., spectra) has to be detected or measured, shape processing can be useful. The distribution function method enables all the information in the signal shape to be utilized, by working with normalized integrals. The concept of shape also helps in estimating resolution parameters of overlapped peaks. The principles are outlined and some applications in chromatography and Mössbauer spectrography are summarized.