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Radiative transfer models of two transitional type Ia supernova (SNe Ia) have been produced using the abundance stratification technique. These two objects --designated SN 2007on and SN 2011iv-- both exploded in the same galaxy, NGC 1404, which allows for a direct comparison. SN 2007on synthesised 0.25 $M_{\odot}$ of $^{56}$Ni and was less luminous than SN 2011iv, which produced 0.31 $M_{\odot}$ of $^{56}$Ni. SN 2007on had a lower central density ($\rho_{c}$) and higher explosion energy ($E_{\rm kin}$ $\sim 1.3\pm$0.3$\times10^{51}$erg) than SN 2011iv, and it produced less nuclear statistical equilibrium (NSE) elements (0.06 $M_{\odot}$). Whereas, SN 2011iv had a larger $\rho_{c}$, which increased the electron capture rate in the lowest velocity regions, and produced 0.35 $M_{\odot}$ of stable NSE elements. SN 2011iv had an explosion energy of $E_{\rm kin}$ $\sim 0.9 \pm$0.2$\times10^{51}$erg. Both objects had an ejecta mass consistent with the Chandrasekhar mass (Ch-mass), and their observational properties are well described by predictions from delayed-detonation explosion models. Within this framework, comparison to the sub-luminous SN 1986G indicates SN 2011iv and SN 1986G have different transition densities ($\rho_{tr}$) but similar $\rho_{c}$. Whereas, SN 1986G and SN 2007on had a similar $\rho_{tr}$ but different $\rho_{c}$. Finally, we examine the colour-stretch parameter $s_{BV}$ vs. $L_{max}$ relation and determine that the bulk of SNe Ia (including the sub-luminous ones) are consistent with Ch-mass delayed-detonation explosions, where the main parameter driving the diversity is $\rho_{tr}$. We also find $\rho_{c}$ to be driving the second order scatter observed at the faint end of the luminosity-width relationship., Comment: Accepted for publication in MNRAS

A comparative investigation into the chemical reactions of a series of fluorinated fullerenes (C60F18, C60F36 and C60F48) with a variety of activated metal surfaces is reported. New ways of generating intense beams of metal fluoride anions are demonstrated: either in reactions of fluorinated fullerene vapours with hot W and Mo metal surfaces in a plasma ion source or by laser desorption/ionisation (LDI) of solid fluorinated fullerenes from various metal substrates (Al, Fe, Cu, Pt, W). In both cases, the resulting metal fluorides and their anions are formed in the highest oxidation state, yielding molybdenum and tungsten hexafluoride anions (plasma ion source), aluminium and iron tetrafluoride anions, and copper trifluoride anions (LDI). No reactions were observed with Pt and W in LDI. The reactivity of the metals towards fluorination correlates with their positions in the metal activity series. Relative yields of bare metal cations are dictated by their ionisation energy. The yield of metal fluoride anions is strongly dependent on the fluorine content of the fluorofullerenes. (C) 2016 Elsevier B.V. All rights reserved.

International audience; Several methods for analyzing pesticides in honey have been developed. However, they do not always reach the sufficiently low limits of quantification (LOQ) needed to quantify pesticides toxic to honey bees at low doses. To properly evaluate the toxicity of pesticides, LOQ have to reach at least 1 ng/g. In this context, we developed extraction and analytical methods for the simultaneous detection of 22 relevant insecticides belonging to three chemical families (neonicotinoids, pyrethroids, and pyrazoles) in honey. The insecticides were extracted with the QuEChERS method that consists in an extraction and a purification with mixtures of salts adapted to the matrix and the substances to be extracted. Analyses were performed by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) for the pyrazoles and the pyrethroids and by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) for the neonicotinoids and ethiprole. Calibration curves were built from various honey types fortified at different concentrations. Linear responses were obtained between 0.2 and 5 ng/g. Limits of detection (LOD) ranged between 0.07 and 0.2 ng/g, and LOQ ranged between 0.2 and 0.5 ng/g. The mean extraction yields ranged between 63 % and 139 % with RSD

The use of pesticides to protect crops against plagues and insects is one of the most important ways to assure agricultural quality and productivity. However, bad application practices may cause the contamination of different environmental compartments and animal species, as a consequence of migration or accumulation of those compounds. Fipronil, imidacloprid and thiametoxam are systemic or systemic-like insecticides widely used in maize crops. Their heavy action in the nervous system of target insects also means a high toxicity to nontarget pollinator insects such as honey bees which can get in touch with them through pollen and nectar during foraging activities. These insecticides have even been suspected to cause a significant decrease of honeybee colonies that has been observed in many countries since the past decade. Since September 1 st 2008, the European Commission set new MRLs in food and feed of plant and animal origin. The pesticides included in this study have MRLs in honey and pollen between 10 and 50 ng g(-1). In the present work, an analytical method was developed with the aim of determining residues of fipronil and some of its metabolites (fipronil sulfone, fipronil sulfide, fipronil desulfinyl and fipronil carboxamide), thiamethoxam and imidacloprid in honey and pollen samples. The extraction optimization was performed using a Doehlert experimental design by studying two factors, the mixture and the ratio of solvents used. Prior to the extraction procedure, raw hive samples containing honey, pollen and wax were centrifuged at 4000 rpm. The upper solid material was removed, and 1 g of the lower phase was mixed with 3 mL of the optimized mixture of methanol/water (10/90). The extract was passed through a florisil cartridge and the target compounds were eluted with methanol and analysed by LC-MS/MS in selective reaction monitoring (SRM) mode. The method was validated according to the guidelines included in the SANCO/10684/2009 document and the ISO 11843 standard for the following parameters: decision limit (CC alpha), detection capability (CC beta), recovery, repeatability and reproducibility at 0.5, 1 and 1.5 folds the MRLs. Ion suppression/enhancement effects into the ion source were also assessed. The CC beta values were included between 0.83 and 4.83 ng g(-1), well below the current MRLs. The validated method was applied to the determination of the target pesticides in 91 samples collected in colonies from 73 apiaries of NW Spain (two sampling campaigns during 2008). None of the target insecticides were detected among all the collected samples. (C) 2010 Elsevier BM. All rights reserved. Analytica Chimica Acta

The charge transfer process in collisions of excited (n = 2, 3) hydrogen atoms with He+ and in collisions of excited helium atoms with H+ is studied theoretically. A combination of a fully quantum-mechanical method and a semi-classical approach is employed to calculate the charge-exchange cross sections at collision energies from 0.1 eV u-1 up to 1 keV u-1. These methods are based on accurate ab initio potential energy curves and non-adiabatic couplings for the molecular ion HeH+. Charge transfer can occur either in singlet or in triplet states, and the differences between the singlet and triplet spin manifolds are discussed. The dependence of the cross section on the quantum numbers n and l of the initial state is demonstrated. The isotope effect on the charge transfer cross sections, arising at low collision energy when H is substituted by D or T, is investigated. Rate coefficients are calculated for all isotopes up to 106 K. Finally, the impact of the present calculations on models of laboratory plasmas is discussed., SCOPUS: ar.j, info:eu-repo/semantics/published

We have studied multiple ionization and dissociation of a trapped protonated peptide (leucine enkephalin) as induced by keV singly and doubly charged ions (H(+), He(+,) (2+)) to demonstrate the potential of keV ions as a future tool for peptide identification. In contrast to conventional excitation techniques, the fragmentation pattern exhibits very strong peaks due to loss of sidechains in addition to those due to backbone scission. The results can be understood on the basis of the energy deposited into the peptide via electronic stopping. A pronounced dependence of the fragmentation pattern on the electronic structure of the projectile ions can be attributed to different electron capture efficiencies from localized molecular orbitals.

Ratios of equilibrium charge-state yields for singly to doubly ionized He-3 ions at an energy of 420 MeV were measured using the Grand Raiden magnetic spectrometer at RCNP. Targets with atomic numbers of 6, 12, 28, 40, 50 and 82 were used. It is found that theoretical calculations for atomic electron-capture and stripping cross sections, which have been successful in describing the data up to beam energies of 200 MeV, are also applicable at this higher energy. However, where at the lower energies the stripping cross sections were calculated with a combination of models by Bohr and Gillespie, the best description of the data at E(He-3) = 420 MeV is obtained when using only the model by Gillespie. The experimental results are also compared with calculations using the code CHARGE, originally developed for fast, heavy (Z > 29) projectiles, to test the extrapolation to low-Z projectiles. It is found that the code underestimates the production of singly-charged He-3 ions, in particular for heavier target nuclei. (c) 2007 Elsevier B.V. All rights reserved.

This work is focused on the effectiveness of headspace solid-phase microextraction (HS-SPME) for the analysis of nine organophosphorus (OPs) insecticides (dimethoate, diazinon, fenitrothion, malathion, fenthion, parathion ethyl, methyl bromophos, methidathion, ethion) and four metabolites (omethoate, malaoxon, fenthion sulfoxide and fenthion sulfone) residues in olive oil samples. The efficiency of six fibre types with different film thickness was compared. PDMS (100 mu m) was found to be the most suitable fibre for the analysis of OPs in olive oils. Optimization of SPME conditions (stirring rate, extraction time, temperature, salt addition) was based on previous developed method in the laboratory that was enriched with additional analytes including major metabolites. In addition, the effect of the oil matrix on the pesticide recoveries was evaluated using spiked oil samples of different composition (acidity, fatty acids, triglycerides, sterols). It was found that only acidity and total amount of sterols are the main factors influencing the SPME efficiency. Matrix effects were compensated for, by using the internal standard method for the quantification of pesticides. The recoveries at three spiking levels were between 80% and 106% with R.S.D. (%) values below 10% in most cases. Good linearity (R-2 > 0.985) was observed in the 0.025-0.50 mg kg(-1) concentration range with satisfactory R.S.D. (%) values of 4.5-10.4%. The method allowed detection of the tested compounds at concentrations below 0.010 mg kg(-1) with GC-FTD detection. In addition, intra- and inter-day precision was satisfactory (R.S.D. (%) < 10%). The performance results confirm the usefulness of the proposed methodology for the analysis of OPs in olive oils. Moreover, the maximum residue limits required by European and international regulations can be attained without difficulty. Finally, the method was applied to 30 virgin olive oil samples from major olive production areas of Greece in the framework of an extended monitoring survey of OPs residues in olive oil. The most commonly found pesticides were fenthion, dimethoate and ethion in levels that did not exceed the MRLs. (c) 2006 Elsevier B.V. All rights reserved. Analytica Chimica Acta

Despite recent advances in our understanding of the significance of the protein glycosylation, the throughput of protein glycosylation analysis is still too low to be applied to the exhaustive glycoproteomic analysis. Aiming to elucidate the N-glycosylation of murine epidermis and dermis glycoproteins, here we used a novel approach for focused proteomics. A gross N-glycan profiling (glycomics) of epidermis and dermis was first elucidated both qualitatively and quantitatively upon N-glycan derivatization with novel, stable isotope-coded derivatization reagents followed by MALDI-TOF(/TOF) analysis. This analysis revealed distinct features of the N-glycosylation profile of epidermis and dermis for the first time. A high abundance of high mannose type oligosaccharides was found to be characteristic of murine epidermis glycoproteins. Based on this observation, we performed high mannose type glycoform-focused proteomics by direct tryptic digestion of protein mixtures and affinity enrichment. We identified 15 glycoproteins with 19 N-glycosylation sites that carry high mannose type glycans by off-line LC-MALDI-TOF/TOF mass spectrometry. Moreover the relative quantity of microheterogeneity of different glycoforms present at each N-glycan binding site was determined. Glycoproteins identified were often contained in lysosomes (e.g. cathepsin L and gamma-glutamyl hydrolase), lamellar granules (e.g. glucosylceramidase and cathepsin D), and desmosomes (e g. desmocollin 1, desmocollin 3, and desmoglein). Lamellar granules are organelles found in the terminally differentiating cells of keratinizing epithelia, and desmosomes are intercellular junctions in vertebrate epithelial cells, thus indicating that N-glycosylation of tissue-specific glycoproteins may contribute to increase the relative proportion of high mannose glycans. The striking roles of lysosomal enzymes in epidermis during lipid remodeling and desquamation may also reflect the observed high abundance of high mannose glycans.

Strong X-ray and far-ultraviolet emission from comets is the direct result of charge exchange reactions of solar wind ions with the neutral coma of comets. Here we report experimental state-selective cross sections of electron capture and use these to predict cometary line emission. Our results show that helium line ratios are a direct diagnostic of the solar wind velocity, while their absolute intensities are linked to the local density of the solar wind. Comparison with observations of Hale-Bopp yields a velocity of 220 km s(-1) and a helium density of 0.6 cm(-3), and observations of Hyakutake show that it interacted with a faster wind of 375 km s(-1) and a helium density of 10(-3) cm(-3). The potential of line emission by heavy minor ions is also demonstrated. Spectral lines with energies greater than 650 eV contain a wealth of information on the original composition of the wind, while lines at lower energies are used best to study the interaction processes themselves.

Strong X-ray and far-ultraviolet emission from comets is the direct result of charge exchange reactions of solar wind ions with the neutral coma of comets. Here we report experimental state-selective cross sections of electron capture and use these to predict cometary line emission. Our results show that helium line ratios are a direct diagnostic of the solar wind velocity, while their absolute intensities are linked to the local density of the solar wind. Comparison with observations of Hale-Bopp yields a velocity of 220 km s(-1) and a helium density of 0.6 cm(-3), and observations of Hyakutake show that it interacted with a faster wind of 375 km s(-1) and a helium density of 10(-3) cm(-3). The potential of line emission by heavy minor ions is also demonstrated. Spectral lines with energies greater than 650 eV contain a wealth of information on the original composition of the wind, while lines at lower energies are used best to study the interaction processes themselves.

The authors wish to thank the CLIO team (J. M. Ortega, C. Six, G. Perilhous, J. P. Berthet) as well as P. Maitre and V. Steinmetz for their support during the experiments.; International audience; The structure of the Pb2+–deprotonated 2′-deoxyguanosine-5′-monophosphate (dGMP) complex, generated in the gas phase by electrospray ionization, was examined by combining tandem mass spectrometry, mid-infrared multiple-photon dissociation (IRMPD) spectroscopy and ion mobility. In the gas phase, the main binding site of Pb2+ onto deprotonated dGMP is the deprotonated phosphate group, but the question is whether an additional stabilization of the metallic complex can occur via participation of the carbonyl group of guanine. Such macrochelates indeed correspond to the most stable structures according to theoretical calculations. A multiplexed experimental approach was used to characterize the gas-phase conformation of the metallic complex and hence determine the binding mode of Pb2+ with [dGMP]−. MS/MS analysis, observation of characteristic bands by IRMPD spectroscopy, and measurement of the ion mobility collision cross section suggest that gaseous [Pb(dGMP)-H]+ complexes adopt a macrochelate folded structure, which consequently differs strongly from the zwitterionic forms postulated in solution from potentiometric studies.

The interaction of multiply charged ions with fullerenes is governed by electron capture as well as nuclear and electronic stopping, The fullerene excitation due to electronic stopping leads mainly to direct ionization and multifragmentation. Our experiments show that the according patterns in the fragmentation spectra can serve as fingerprints for the electronic stopping. A quantitative analysis of the cross sections for ionization and multifragmentation reveals the characteristic linearity in the projectile velocity v as well as an oscillatory dependence on the projectile atomic number Z. The pi -electron dominated electronic structure of fullerenes has some similarities to that of biomolecular species. Qualitatively similar dynamics are therefore expected to occur in HCI collisions with biomolecules. First experimental results indeed indicate a strong dependence of the fragmentation pattern on projectile charge state and velocity.

Dynamic processes induced by the high potential energy of multiply charged ions have been investigated in a large number of collision systems during the last years. We give a review of these activities with special emphasis on the developments since the last ICPEAC in Vienna 1997.

Experimental and theoretical cross sections for the excitation of ground-state lithium by Hf and He2+ impact are presented for the 2-30 keV/amu energy regime. Li(2s) excitation up to the Li(n = 4) level was simulated by means of the atomic-orbital close-coupling method. Experimentally, absolute emission cross sections were determined by observing the LiI(nd-2p,n = 3-6) and LiI(ns-2p,n = 4-6) line radiation after ion impact. Furthermore, a few measurements have been performed on high-n excitation [Li(2s-->nd,n = 7-9)] by He2+ impact. [S1050-2947(99)06912-7].

The dissociation of COq+ ions (q less than or equal to 3) produced in collisions of keV amu(-1) He2+ ions with CO has been studied by time-of-flight measurements. Both singles and coincidence time-of-flight techniques have been used to determine the kinetic energy release of the dissociating CO molecules. We describe the method to transform the singles and coincidence time-of-flight spectra into total kinetic energy distributions and discuss these distributions. They represent kinetic energy release distributions which clearly exhibit various contributions associated with different dissociation channels. In comparison with other ionization methods similarities but also clear differences are noted.

The dissociation of COq+ ions (q less than or equal to 3) produced in collisions of 2-10 keV amu(-1) He2+ ions with CO has been studied by time-of-flight methods. From the time-of-flight spectra the energy released in the dissociation process is determined. Our results for the kinetic energy release of CO2+ and CO3+ ions are compared with the results of other ionization methods. Clear differences are observed. We observe a counterintuitive dependence of the kinetic energy release on the velocity of the He2+ ions, i.e. the kinetic energy release increases with decreasing velocity.

Dissociation of CO molecules by collisions with He{sup 2+} and O{sup 7+} at keV energies has been investigated by measuring the charge states and kinetic energies of the ionized fragments in coincidence with each other. As opposed to earlier investigations with fast (MeV) projectiles we find that the kinetic energies of the fragment ions are strongly influenced by the projectiles{close_quote} charge and velocity; e.g., O{sup 7+} impact results in 50{percent} {ital less} kinetic energy release in the C{sup +}-O{sup +} fragmentation than He{sup 2+} impact. For a qualitative understanding of these effects we invoke the classical overbarrier model. {copyright} {ital 1996 The American Physical Society.}

We have used photon emission spectroscopy to determine absolute, state-selective cross sections for single-electron capture by O3+ ions colliding on atomic and molecular hydrogen. The impact energy was varied between 45 and 752 eV amu(-1). For O3+ + H collisions we find that the cross section for capture into the 2p3s state of O2+ strongly increases with impact energy up to an energy of approximate to 100 eV amu(-1). At higher impact energies the 2p3s cross section becomes comparable to the more or less constant 2p3p cross section. For the O3+ + H-2 system these state-selective cross sections both stay approximately constant over the entire energy range investigated. Our results will be compared with existing experimental and theoretical data.

We investigated l and m-distributions of He II (n = 4) states formed during 2-13.3 keV amu(-1) He2+ + Na(3s) collisions by measuring profiles and the linear polarization of the He II (4 --> 3) emission. We found that at these energies capture into He+(4f) dominates over capture into other He+(4l) states. Over the indicated energy range the polarization of the He-4 II (4 --> 3) photon emission increases from 0.2 to 0.3 indicating a strong alignment of the captured projectile charge cloud along the internuclear axis. Due to the non-zero nuclear spin the polarization is up to 10% lower when using He-3(2+) projectiles instead of He-4(2+). Classical trajectory Monte Carlo calculations agree quantitatively with these experimental findings and predict a decrease of the polarization towards zero at higher energies due to enhanced capture into He+(4s).A positive polarization is also found for the Na I (3p --> 3s) target de-excitation. However, due to strong depolarization effects caused by the nuclear spin of the Na-23 nucleus it stays below 0.14.

The average deflection of a laser excited, divergent sodium beam with a broad velocity distribution is measured by means of a Langmuir-Taylor detector and exploited for determining the absolute density of the excited state in the interaction area. Simulations of the excitation and deflection process point out that the knowledge of the velocity distribution of the sodium atoms plays a crucial part in obtaining reliable information from deflection measurements. From the comparison of simulated and experimental results we find that in our set-up typically 30% of the sodium atoms are in the excited state when both ground state levels are pumped with an intensity of 35 mW cm-2 from an electro-optically modulated CW laser beam; the corresponding excited state density is 1.5 x 10(9) cm-3.

Die Dissertation behandelt den Aufbau einer crossed-beam-Experimentieranlage zum Studium winkelaufgelöster Autoionisationsprozesse aus Ion-Atom-Stößen. Erste experimentelle Ergebnisse dieser Anlage werden diskutiert. Für die Stoßsysteme C^{5+}+He und O^{7+}+He wurden die Anisotropie-Koeffizienten von doppelt-angeregten 1s2l2l´-2L Zuständen bestimmt. Aus diesen Koeffizienten kann auf die Bevölkerung verschiedener magnetischer Unterzustände geschlossen werden., A crossed-beam setup is presented facilitating angle resolved high-resolution spectroscopy of electrons emerging from ion-atom collisions. The collision systems C^{5+}+He and O^{7+}+He were investigated by measuring the anisotropy coefficients of the Auger decay of doubly excited 1s2l2l´2L states. From these coefficients one can derive the population of different magnetic substates.

Double-differential cross sections of the Fe-54,Fe-56(n, p) reactions have been measured at 97 MeV in the angular range 0-30-degrees for excitation energies up to 40 MeV. The spectra have been decomposed into different multipolarities by a technique based on the use of sample angular distributions calculated within the distorted-wave Born approximation. From the identified Gamow-Teller strength, S(beta)+ values were obtained for Fe-54 Fe and Fe-56. Comparisons with available shell-model calculations of the GT strength were made. The results are important for models of supernova explosions since electron-capture rates, which are proportional to S(beta)+, in 1f2p-shell nuclei affect the dynamics of the star. At higher excitation energies, the spectra are dominated by L = 1 strength in broad distributions with a maximum at about 12 MeV. Microscopic calculations based on the random-phase approximation were performed and compared with the experimental data.

Processes for charge transfer into He2+ colliding with the atomic isotopes hydrogen (H), deuterium (D), and tritium (T) are theoretically studied at collision energies as low as 30 eV/amu. Probabilities and cross sections for electron capture into different shells of the projectile are calculated using an ab initio approach which solves the time-dependent Schrodinger equation. The results are interpreted in terms of radial and rotational couplings between molecular orbitals. The probabilities exhibit strong Stueckelberg oscillations for charge transfer into shells with the principal quantum numbers n = 2 and 3 due to radial coupling mechanisms in specific ranges of the impact parameter. The total cross sections for charge transfer, evaluated for a given shell, differ by orders of magnitude, as different isotopes are used in the collisions. The isotope effect increases significantly for decreasing n = 3, 2, and 1. This finding is attributed to the influence of the rotational coupling mechanism, which is strongly affected by the distance of closest approach between the collision partners.

Processes for charge transfer into He2+ colliding with the atomic isotopes hydrogen (H), deuterium (D), and tritium (T) are theoretically studied at collision energies as low as 30 eV/amu. Probabilities and cross sections for electron capture into different shells of the projectile are calculated using an ab initio approach which solves the time-dependent Schrodinger equation. The results are interpreted in terms of radial and rotational couplings between molecular orbitals. The probabilities exhibit strong Stueckelberg oscillations for charge transfer into shells with the principal quantum numbers n = 2 and 3 due to radial coupling mechanisms in specific ranges of the impact parameter. The total cross sections for charge transfer, evaluated for a given shell, differ by orders of magnitude, as different isotopes are used in the collisions. The isotope effect increases significantly for decreasing n = 3, 2, and 1. This finding is attributed to the influence of the rotational coupling mechanism, which is strongly affected by the distance of closest approach between the collision partners.

An electrochemical method for the determination of azinphos-methyl and parathion-methyl in honey is presented. The determination is established by adsorptive stripping differential pulse voltammetry at hanging mercury working electrode. In contrast to the chromatographic methods for the determination of pesticide residues, the sample preparation of the proposed method is minimal; analytes were extracted from honey samples with a mixture of (acetone):(Britton-Robinson buffer) and then were analyzed without any additional pretreatment. The response of the analytes either individually or as a mixture was studied for a series of deposition time and molar ratio. Two quantitation protocols were compared, using either the external calibration or the standard addition method. Accuracy was tested with spiked honey samples obtaining good recovery values. The limit of detection for the honey sample (for deposition time of 10 s) was calculated 51.71 mu g kg(-1) for MeP and 65.87 mu g kg(-1) for AzMet. (C) 2010 Elsevier Ltd. All rights reserved. Electrochimica Acta

In the energy range of 3 x 10(2) to 5 x 10(5) eV/amu, data for total and state selective electron capture in collisions of protons with helium have been evaluated critically. From this investigation, a set of recommended data has been constructed which are part of the atomic database in JET and which, therefore, are used for modelling of helium beam stopping and related diagnostics. Motivation for the assessment of the cross-sections is presented and the corresponding uncertainties are inferred.

Thermal alpha particles are observed in JET during helium discharges using spectral emission in He II (n = 4 --> 3) near 4685 angstrom following charge transfer reactions along the path of the neutral deuterium heating beams. New and reappraised He2+/H charge transfer cross-sections are presented. The effects of cross-section energy dependence on temperatures, velocities and absolute densities deduced from thermal alpha particle charge exchange spectra are evaluated. The possibility of detecting fusion alpha particles produced at 3.5 MeV and slowing down by collisions with plasma electrons and ions using visible charge exchange spectroscopy is addressed. The spectral signature of slowing-down fusion alpha particles expected during the deuterium- tritium phase of JET is modelled and its identification against thermal alpha particle and background radiation is investigated.

International audience; The Saturn magnetosphere interacts with the Titan atmosphere through various mechanisms. One of them leads, by charge exchange reactions between the energetic Saturnian ions and the exospheric neutrals of Titan, to the production of energetic neutral atoms (ENAs). The Ion and Neutral Camera (INCA), one of the three sensors that comprise the Magnetosphere Imaging Instrument (MIMI) on the Cassini/Huygens mission to Saturn and Titan, images the ENA emissions in the Saturnian magnetosphere. This study focuses on the ENA imaging of Titan (for 20–50 keV H ENAs), with the example of the Ta Titan flyby (26 October 2004): our objective is to understand the positioning of the ENA halo observed around Titan. Thus we investigate the main ENA loss mechanisms, such as the finite gyroradii effects for the parent ions, or the charge stripping with exospheric neutrals. We show that multiple stripping and charge exchange reactions have to be taken into account to understand the ENA dynamics. The use of an analytical approach, taking into account these reactions, combined with a reprocessing of the INCA data, allows us to reproduce the ENA images of the Ta flyby and indicates a lower limit for ENA emission around the exobase. However, the dynamics of energetic particles through the Titan atmosphere remains complex, with an inconsistency between the ENA imaging at low and high altitudes.

A simple, rapid and sensitive GC-MS method for the determination of dithiocarbatnate fungicide propineb [polymeric zinc propylenebis (dithiocarbamate)] and an improved HPLC procedure for the simultaneous determination of its main metabolite, propylenethiourea, and ethylenethiourea, the main metabolite of all ethylenedithiocarbamates, in airborne samples are described. The method for the analysis of propineb involves the evolution of carbon disulfide (CS,), under acidic conditions in the presence of stannous chloride, extraction of the generated CS, into a layer of isooctane which is then analyzed for CS, content by GC-MS in SIM mode. Under the optimum conditions, the retention time Of CS2 was 1.89 min and the total time of chromatographic analysis was 5 min. Recoveries from spiking glass microfibre filters (GF/A) and silica gel filters were 86 +/- 7 (n = 9) and 89 +/- 4 (n = 9), respectively. The limit of detection is 0.7 ng per filter, which is equivalent to about 0.8-1.0 ng m(-3) in air. In parallel, an HPLC method with ultraviolet detection is presented for the simultaneous analysis of the metabolites. Separation of the two metabolites was attained in less than 5 min. Recoveries from spiking GF/A and silica gel filters for ethylenethiourea were 100 +/- 1 (n = 3) and 98 +/- 2 (n = 3), respectively, while for propylenethiourea were 102 +/- 1 (n = 3) and 98 +/- 1 (n = 3), respectively. The detection limits are about 36-43 and 40-49 ng m(-3) in air for ethylenethiourea and propylenethiourea, respectively. All the analytes spiked in the filters are proven to be stable for more than one month, at -4 degrees C. (c) 2007 Elsevier Ltd. All rights reserved. Chemosphere

We present extensive Monte Carlo simulations, showing that cold antihydrogen ((H) over bar) atoms are produced when antiprotons ((p) over bar) are gently heated in the side wells of a nested Penning trap. The observed (H) over bar with high energies, that had seemed to indicate otherwise, are instead explained by a surprisingly effective charge-exchange mechanism. We shed light on the previously measured field-ionization spectrum, and reproduce both the characteristic low-field power law as well as the enhanced (H) over bar production at higher fields. The latter feature is shown to arise from (H) over bar atoms too deeply bound to be described as guiding center atoms, atoms with internally chaotic motion.

We investigate fragmentation of CO molecules by collisions of He2+ ions at energies between 2 and 11 keV/amu by means of a reflectron time-of-flight (TOF) spectrometer. The kinetic-energy-release (KER) in the center of mass system of the molecule can be determined from the flight times of these particles. Different dissociation processes leading to different amounts of released energy and different fragments can be identified. The KER differs from the one expected from the pure Coulomb repulsion of two point charges, starting at the CO equilibrium distance and depended strongly on the collision energy. This will be discussed in terms of the classical overbarrier model. Furthermore, there is a strong influence of the projectile type on the KER. A feature of the experiments, namely the strong dependence of the KER on the projectile kinetic energy, is not yet fully understood.

Low-energy ion beams impinging under grazing incidence on surfaces interact inherently with the topmost surface layer(s). The method of electron capture spectroscopy in which the degree of polarization of the light emitted by the neutralized projectiles is analyzed has been used to investigate spin polarization effects at Ni(1 1 0) and Fe(1 1 0) surfaces. The results hint at strong spin filtering mechanisms. With multiply charged instead of singly charged ion beams one may obtain access to short range spin ordering at the surface. Progress in the development of this new, so-called multiple electron capture spectroscopy technique is discussed and first results for He2+ ions interacting with a Ni(1 1 0) surface are presented. (c) 2005 Elsevier B.V. All rights reserved.

Strong X-ray and far-ultraviolet emission from comets is the direct result of charge exchange reactions of solar wind ions with the neutral coma of comets. Here we report experimental state-selective cross sections of electron capture and use these to predict cometary line emission. Our results show that helium line ratios are a direct diagnostic of the solar wind velocity, while their absolute intensities are linked to the local density of the solar wind. Comparison with observations of Hale-Bopp yields a velocity of 220 km s(-1) and a helium density of 0.6 cm(-3), and observations of Hyakutake show that it interacted with a faster wind of 375 km s(-1) and a helium density of 10(-3) cm(-3). The potential of line emission by heavy minor ions is also demonstrated. Spectral lines with energies greater than 650 eV contain a wealth of information on the original composition of the wind, while lines at lower energies are used best to study the interaction processes themselves.

Solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) and selected ion monitoring (SIM) was used for the analytical determination of priority pesticide residues. Fibers coated with a 65-mum film thickness of polydimethylsiloxane divinylbenzene (PDMS-DVB) were used to extract 31 pesticides of different chemical groups. The quality parameters of the method demonstrated a good precision with detection limits of 1-56 ng/L. Linearity was controlled in the range of 0.1-50 mug/L. The proposed method was applied for the trace-level determination of the target pesticides in surface water samples including three rivers and one lake at the Epirus region (north-west Greece) for a period of one year. The results demonstrate the suitability of the SPME-GC-MS approach for the analysis of multi-residue pesticides in environmental water samples. International Journal of Environmental Analytical Chemistry

We studied multiple ionization of single nucleobases by means of slow highly charged ions (${\mathrm{X}\mathrm{e}}^{q+}$, $q=5--25$). The products of the subsequent fragmentation were studied using high resolution coincidence time-of-flight spectrometry. We observed a strong dependence of the fragment kinetic energies on the initial charge state of the intermediate parent ions as well as on the initial chemical environment of the respective fragment ions within the parent molecule. The data allow us to shed light on the charge distribution within the molecule as well as on the fragmentation dynamics of these intermediate size systems.

Two experimental techniques for the determination of the metastable 1s2s S-3 fractions of two-electron ion beams are compared on the basis of their accuracy and applicability. Both techniques utilize the electron yields of the 1s2p(2) D-2 and 1s2s2p P-4 doubly excited states, produced in energetic collisions of two-electron ion beams with H-2 targets. In the first technique, the fraction is determined in a single measurement, incorporating theoretical cross sections for the production of the doubly excited states. In the second technique, the metastable beam fraction is determined in two successive measurements at the same beam energy but with beams having different metastable fractions. Each technique suffers from the same statistical uncertainties but different systematic errors that largely affect their applicability. Results obtained from the two techniques for the B3+ case were in good agreement. (C) 2003 Elsevier Science B.V. All rights reserved. Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms

Measurements of relative multiple ionization cross sections have been performed for 50--300-keV ${\mathrm{H}}^{+},$ ${\mathrm{D}}^{+},$ and ${\mathrm{He}}^{+}$ impact on ${\mathrm{N}}_{2},$ ${\mathrm{O}}_{2},$ CO, and NO molecules. Fragment ions with total charges up to ${Q=q}_{1}{+q}_{2}=5$ have been detected in coincidence using a position- and time-sensitive detector. Dependence of the cross section on the molecular orientation with respect to the ion beam is observed for all targets. The experimental data are compared with theoretical calculations based on the statistical energy deposition model.

Auger spectroscopy has been used to measure the fraction of metastable 1s2s S-3 ions in fast He-like B, C, N, O, and F beams produced in collisions with thin carbon foils as a function of both the incident energy in the range of 0.5-2 MeV/u and the foil thickness in the range of 1-5 mug/cm(2). The method used for determination of the metastable fraction is based on measurements of the electron emission from the doubly excited states of Li-like ions formed in collisions of primary beams with hydrogen and helium targets. Some differences were observed both in the energy dependence and the absolute value of metastable fractions for different beams. In particular, the metastable content in C4+ ions produced in carbon foils was found to be significantly lower than that of other investigated beams. The observed deviation has been explained on the basis of K-vacancy sharing, which is known to have the highest probability for symmetric collisions. A model recently proposed for the calculation of the metastable fraction in He-like beams has been used to predict the metastable fraction for B3+ ions leading to a good agreement with the experiment. Physical Review A

The delocalized \ensuremath{\pi} electrons of a ${\mathrm{C}}_{60}$ cluster can be well described as an electron gas. Electronic friction experienced by a multicharged ion colliding with a fullerene might then be modeled in terms of the electronic stopping power. We investigated such collisions for projectile atomic numbers Z ranging from 2 to 18 and charge states $q=2,3.$ Direct mass-spectrometric evidence of the clear oscillatory behavior of electronic-stopping-related processes such as multifragmentation and ionization of ${\mathrm{C}}_{60}$ was observed as a function of Z. From the positions of the maxima of the corresponding cross sections, two classes of trajectories can be distinguished: close collisions through the high electron density of the cage inducing multifragmentation, and glancing collisions through the lower electron densities of the fullerene ``atmosphere'' inducing direct ionization.

The fraction of metastable ions in B3+ (1s(2) S-1.1s2s S-3) beams produced in collisions with thin-foil and.-as targets has been measured as a function of the incident energy in the range of 0.85-9 MeV. This was done by comparing the electron yield of doubly excited states formed in the collision of B3+ with hydrogen and helium targets. Significant differences were observed in the energy dependence of the metastable fraction between production in foil and gas targets. It was shown that the production of 1s2s S-3 metastable ions in a foil yields a constant fraction over the investigated energy range, unlike the fraction of metastable 1s2s S-3 ions produced in collisions with gas targets. which strongly depends on the incident beam energy. A theoretical study of the processes contributing to the formation of the S-3 metastable ions in collisions with foil and gas has been made. K-vacancy production in the ion-beam stripping process has been identified as a dominant mechanism and used to explain the observed difference in the energy dependence of the metastable fraction between production in collisions with gas and foil targets. A model is proposed for the calculation of the metastable fraction for He-like beams. Physical Review A