Combining microscopic and macroscopic probes to untangle the single-ion anisotropy and exchange energies in an S=1 quantum antiferromagnet

The magnetic ground state of the quasi-one-dimensional spin-1 antiferromagnetic chain is sensitive to the relative sizes of the single-ion anisotropy (D) and the intrachain (J) and interchain (J') exchange interactions. The ratios D/J and J'/J dictate the material's placement in one of three competing phases: a Haldane gapped phase, a quantum paramagnet and an XY-ordered state, with a quantum critical point at their junction. We have identified [Ni(HF)2(pyz)_2]SbF6, where pyz = pyrazine, as a rare candidate in which this behavior can be explored in detail. Combining neutron scattering (elastic and inelastic) in applied magnetic fields of up to 10~tesla and magnetization measurements in fields of up to 60~tesla with numerical modeling of experimental observables, we are able to obtain accurate values of all of the parameters of the Hamiltonian [D = 13.3(1)~K, J = 10.4(3)~K and J' = 1.4(2)~K], despite the polycrystalline nature of the sample. Density-functional theory calculations result in similar couplings (J = 9.2~K, J' = 1.8~K) and predict that the majority of the total spin population resides on the Ni(II) ion, while the remaining spin density is delocalized over both ligand types. The general procedures outlined in this paper permit phase boundaries and quantum-critical points to be explored in anisotropic systems for which single crystals are as yet unavailable

Supplement of Wet deposition in the remote western and central Mediterranean as a source of trace metals to surface seawater [Dataset]

3 pages. -- Figure S1: Atmospheric conditions during rain ION period, the 29 May 2017. -- Figure S2: Atmopsheric conditions during rain FAST period, the 05 June 2017Peer reviewe

High frequency cycling of salt storage caverns research program

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Implementation of an incoherent broadband cavity-enhanced absorption spectroscopy technique in an atmospheric simulation chamber for in situ NO<sub>3</sub> monitoring: characterization and validation for kinetic studies

International audienceAbstract. An incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) technique has been developed for the in situ monitoring of NO3 radicals at the parts per trillion level in the CSA simulation chamber (at LISA). The technique couples an incoherent broadband light source centered at 662 nm with a high-finesse optical cavity made of two highly reflecting mirrors. The optical cavity which has an effective length of 82 cm allows for up to 3 km of effective absorption and a high sensitivity for NO3 detection (up to 6 ppt for an integration time of 10 s). This technique also allows for NO2 monitoring (up to 9 ppb for an integration time of 10 s). Here, we present the experimental setup as well as tests for its characterization and validation. The validation tests include an intercomparison with another independent technique (Fourier-transform infrared, FTIR) and the absolute rate determination for the reaction trans-2-butene + NO3, which is already well documented in the literature. The value of (4.13 ± 0.45) × 10−13 cm3 molecule−1 s−1 has been found, which is in good agreement with previous determinations. From these experiments, optimal operation conditions are proposed. The technique is now fully operational and can be used to determine rate constants for fast reactions involving complex volatile organic compounds (VOCs; with rate constants up to 10−10 cm3 molecule−1 s−1)

Implementation of an incoherent broadband cavity-enhanced absorption spectroscopy technique in an atmospheric simulation chamber for in situ NO<sub>3</sub> monitoring: characterization and validation for kinetic studies

International audienceAbstract. An incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) technique has been developed for the in situ monitoring of NO3 radicals at the parts per trillion level in the CSA simulation chamber (at LISA). The technique couples an incoherent broadband light source centered at 662 nm with a high-finesse optical cavity made of two highly reflecting mirrors. The optical cavity which has an effective length of 82 cm allows for up to 3 km of effective absorption and a high sensitivity for NO3 detection (up to 6 ppt for an integration time of 10 s). This technique also allows for NO2 monitoring (up to 9 ppb for an integration time of 10 s). Here, we present the experimental setup as well as tests for its characterization and validation. The validation tests include an intercomparison with another independent technique (Fourier-transform infrared, FTIR) and the absolute rate determination for the reaction trans-2-butene + NO3, which is already well documented in the literature. The value of (4.13 ± 0.45) × 10−13 cm3 molecule−1 s−1 has been found, which is in good agreement with previous determinations. From these experiments, optimal operation conditions are proposed. The technique is now fully operational and can be used to determine rate constants for fast reactions involving complex volatile organic compounds (VOCs; with rate constants up to 10−10 cm3 molecule−1 s−1)

Water content of limestones submitted to realistic wet deposition: a CIME2 chamber simulation

International audienceAn experimental chamber (CIME2) has been specially designed to simulate wet atmospheric deposition on limestones used inParis cultural heritage. This instrument is a complementary tool to CIME, a previously developed chamber dedicated to thesimulation of dry atmospheric deposition on monuments and artifacts. The aim of this paper is to describe CIME2 and characterizethe wet deposits produced inside it. Mist (fog), drizzle, and rainfall are differentiated in order to document their ability tosaturate the limestones most currently used in Paris monuments: The Saint-Maximin’s limestone, the Liais of Saint-Maximin, andthe Chauvigny’s limestone are tested. The comparison between normalized and environmental petrophysical data shows that inthe wet deposition simulations, limestones are not systematically water-saturated. Moreover, the realistic experimental conditionschosen favor a more rapid evaporation of the stone water. The quantification of the non-saturation state is a first step that has to betaken into account to improve the geochemical models used to predict the alteration

Overview of atmospheric composition in Western Mediterranean during PEACETIME cruise

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ILMA: Ion Laser Mass Analyser. A High-Resolution Mass-Spectrometer for In-Situ Characterization of a Near Earth Asteroid (NEA).

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Summertime surface PM 1 aerosol composition and size by source region at the Lampedusa island in the central Mediterranean Sea

International audienceMeasurements of aerosol composition and size distributions were taken during the summer of 2013 at the remote island of Lampedusa in the southern central Mediterranean Sea. These measurements were part of the ChArMEx/ADRIMED (Chemistry and Aerosol Mediter-ranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate) framework and took place during Special Observation Period 1a (SOP-1a) from 11 June to 5 July 2013. From compact time-of-flight aerosol mass spectrometer (cToF-AMS) measurements in the size range below 1 µm in aerodynamic diameter (PM 1), particles were predominately comprised of ammonium and sulfate. On average, ammo-nium sulfate contributed 63 % to the non-refractory PM 1 mass, followed by organics (33 %). The organic aerosol was generally very highly oxidized (f 44 values were typically between 0.25 and 0.26). The contribution of ammonium sulfate was generally higher than organic aerosol in comparison to measurements taken in the western Mediterranean but is consistent with studies undertaken in the eastern basin. Source apportionment of organics using a statistical (pos-itive matrix factorization) model revealed four factors: a hydrocarbon-like organic aerosol (HOA), a methanesulfonic-acid-related oxygenated organic aerosol (MSA-OOA), a more oxidized oxygenated organic aerosol (MO-OOA) and a less oxidized oxygenated organic aerosol (LO-OOA). The MO-OOA was the dominant factor for most of the campaign (53 % of the PM 1 OA mass). It was well correlated with SO 2− 4 , highly oxidized and generally more dominant during easterly air masses originating from the eastern Mediter-ranean and central Europe. The LO-OOA factor had a very similar composition to the MO-OOA factor but was more prevalent during westerly winds, with air masses originating from the Atlantic Ocean, the western Mediterranean and at high altitudes over France and Spain from mistral winds. The MSA-OOA factor contributed an average 12 % to the PM 1 OA and was more dominant during the mistral winds. The HOA, representing observed primary organic aerosol, only contributed 8 % of the average PM 1 OA during the campaign. Even though Lampedusa is one of the most remote sites in the Mediterranean, PM 1 concentrations (10 ± 5 µg m −3) Published by Copernicus Publications on behalf of the European Geosciences Union. 11124 M. D. Mallet et al.: Summertime PM 1 composition and size in the remote Mediterranean were comparable to those observed in coastal cities and sites closer to continental Europe. Cleaner conditions corresponded to higher wind speeds. Nucleation and growth of new aerosol particles was observed during periods of north-westerly winds. From a climatology analysis from 1999 to 2012, these periods were much more prevalent during the measurement campaign than during the preceding 13 years. These results support previous findings that highlight the importance of different large-scale synoptic conditions in determining the regional and local aerosol composition and oxidation and also suggest that a non-polluted surface atmosphere over the Mediterranean is rare