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Papers by Caroline Raepsaet
Characterization of 81P/Wild 2 Particles C2103,1,98,1,0, C2103,1,98,2,0, and C2065,1,97,1,0
Three aerogel-coated Stardust grains have organics and CI-like Cr/, Mn/, Ni,/ and Zn/Fe ratios. S... more Three aerogel-coated Stardust grains have organics and CI-like Cr/, Mn/, Ni,/ and Zn/Fe ratios. Some flight aerogel has 5 wt% C. C and N in 30×30 µm areas of Alais and Orgueil match CI values to within a factor of two. Coal shot into aerogel left a track but no terminal particle.
Earth and Planetary Science Letters, 2015
Earth and Planetary Science Letters, 2014
Journal of Nuclear Materials, 2015
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2014
ABSTRACT Uranium and plutonium carbides are candidate fuels for Generation IV nuclear reactors. T... more ABSTRACT Uranium and plutonium carbides are candidate fuels for Generation IV nuclear reactors. This study is focused on the characterization of uranium monocarbide samples. The successive fabrication steps were carried out under atmospheres containing low oxygen and moisture concentrations (typically less than 100 ppm) but sample transfers occurred in air. Six samples were sliced from four pellets elaborated by carbothermic reaction under vacuum. Little presence of UC2 is expected in these samples. The α-UC2 phase was indeed detected within one of these UC samples during an XRD experiment performed with synchrotron radiation. Moreover, oxygen content at the surface of these samples was depth profiled using a recently developed nuclear reaction analysis method. Large oxygen concentrations were measured in the first micron below the sample surface and particularly in the first 100-150 nm. UC2 inclusions were found to be more oxidized than the surrounding matrix. This work points out to the fact that more care must be given at each step of UC fabrication since the material readily reacts with oxygen and moisture. A new glovebox facility using a highly purified atmosphere is currently being built in order to obtain single phase UC samples of better purity.
We studied the simultaneous transfer of Zn, Cd and P b in a calcareous substrate, extracted from ... more We studied the simultaneous transfer of Zn, Cd and P b in a calcareous substrate, extracted from a fluvi o-glacial deposit that is used to infiltrate stormwater. Labo ratory column experiments showed that Pb retention was the strongest, as expected. However, Zn and Cd retention s were almost equal, in disagreement with conventio nal modelling assumptions. Investigations based on PHREEQC reactive modelling and both scanning electron microscopy (SEM) and PIXE / RBS analysis (nuclear microprobe) proved that Zn and Cd did not precipitate separately as smithsonite and otavite as usually ob served under these experimental conditions. These investigations point at a surface substitution proc ess in which Ca is successively replaced by metals s uch as Zn and Cd on surface sites, followed by diffusion of th ese metals into the lattice of the calcareous parti cles.
Geochimica et Cosmochimica Acta, 2009
Geochimica et Cosmochimica Acta, 2010
Earth and Planetary Science Letters, 2014
Earth and Planetary Science Letters, 2014
ABSTRACT The mechanism and magnitude of fluorine incorporation in H-bearing forsterite were inves... more ABSTRACT The mechanism and magnitude of fluorine incorporation in H-bearing forsterite were investigated through a combined experimental and theoretical approach. Forsterite samples were synthesized in a piston cylinder press at 2 and 4 GPa, in hydrous conditions, with or without fluorine. High fluorine solubilities of 1715 and 1308 ppm F were measured by particle induced gamma-ray emission (PIGE) in forsterite samples synthesized at 2 and 4 GPa, respectively. In addition, first-principles calculations based on density functional theory were performed in order to investigate the coupled incorporation mechanisms of fluorine and water in forsterite. Our results demonstrate the close association of fluoride, hydroxyl groups and Si vacancies. Comparison of experimental and theoretical infrared absorption spectra enables assignment of the nine OH stretching bands (3500–3700 cm−1) observed in F-rich synthetic forsterite to clumped fluoride-hydroxyl defects in the forsterite crystal structure. Noteworthily, similar bands were previously recorded on some natural olivine with Mg/(Mg+Fe) molar ratio down to 0.86. Fluorine and water cycles are therefore strongly coupled through the nominally anhydrous minerals and the mantle fluorine budget can be entirely accommodated by these mineral phases.
Chemical Geology, 2009
... The most common absolute methods used to quantify hydrogen in glasses or minerals are manomet... more ... The most common absolute methods used to quantify hydrogen in glasses or minerals are manometry (eg, [Dobson et al., 1989] and [Bell et al., 1995]), Karl-Fisher titration (KFT) (eg,Behrens et al., 1996), nuclear reaction analysis (eg, Bell et al., 2003) and elastic recoil ...
Chemical Geology, 2012
ABSTRACT Elastic recoil detection analysis (ERDA) was used to measure the H contents of 18 synthe... more ABSTRACT Elastic recoil detection analysis (ERDA) was used to measure the H contents of 18 synthetic Fo(90) olivines that had been hydrated to varying degrees in high pressure hydrothermal experiments. The infrared spectra of the olivines have been previously measured in the OH stretching region by Fourier transform infrared spectroscopy, and (OH)-O-16-H-1 secondary ion mass spectroscopy measurements have been made on the same samples. Mapping by ERDA, Rutherford backscattering and particle induced X-ray emission spectroscopies show that the synthetic olivines are homogeneous with respect to major element and H concentrations. Concentrations of H measured by ERDA vary between 270 and 2120 ppm H2O. Measurements of OH/Si ratios by secondary ion mass spectroscopy and of total integrated area of OH stretching bands in principal absorption spectra by FTIR show excellent linear relationships to H concentrations determined by ERDA. The ERDA measurements are used to determine an infrared integral molar absorption coefficient of 45,200 I mol(-1) cm(-2) that can be used to determine H contents of olivines from high pressure experiments. The H content of Fo(90) olivines (in wt. ppm H2O) is given by 0.119 +/- 0.006 x total integrated absorbance per cm thickness. (C) 2012 Elsevier B.V. All rights reserved.
Solid State Phenomena, 2011
Characterization of 81P/Wild 2 Particles C2103,1,98,1,0, C2103,1,98,2,0, and C2065,1,97,1,0
Three aerogel-coated Stardust grains have organics and CI-like Cr/, Mn/, Ni,/ and Zn/Fe ratios. S... more Three aerogel-coated Stardust grains have organics and CI-like Cr/, Mn/, Ni,/ and Zn/Fe ratios. Some flight aerogel has 5 wt% C. C and N in 30×30 µm areas of Alais and Orgueil match CI values to within a factor of two. Coal shot into aerogel left a track but no terminal particle.
Earth and Planetary Science Letters, 2015
Earth and Planetary Science Letters, 2014
Journal of Nuclear Materials, 2015
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2014
ABSTRACT Uranium and plutonium carbides are candidate fuels for Generation IV nuclear reactors. T... more ABSTRACT Uranium and plutonium carbides are candidate fuels for Generation IV nuclear reactors. This study is focused on the characterization of uranium monocarbide samples. The successive fabrication steps were carried out under atmospheres containing low oxygen and moisture concentrations (typically less than 100 ppm) but sample transfers occurred in air. Six samples were sliced from four pellets elaborated by carbothermic reaction under vacuum. Little presence of UC2 is expected in these samples. The α-UC2 phase was indeed detected within one of these UC samples during an XRD experiment performed with synchrotron radiation. Moreover, oxygen content at the surface of these samples was depth profiled using a recently developed nuclear reaction analysis method. Large oxygen concentrations were measured in the first micron below the sample surface and particularly in the first 100-150 nm. UC2 inclusions were found to be more oxidized than the surrounding matrix. This work points out to the fact that more care must be given at each step of UC fabrication since the material readily reacts with oxygen and moisture. A new glovebox facility using a highly purified atmosphere is currently being built in order to obtain single phase UC samples of better purity.
We studied the simultaneous transfer of Zn, Cd and P b in a calcareous substrate, extracted from ... more We studied the simultaneous transfer of Zn, Cd and P b in a calcareous substrate, extracted from a fluvi o-glacial deposit that is used to infiltrate stormwater. Labo ratory column experiments showed that Pb retention was the strongest, as expected. However, Zn and Cd retention s were almost equal, in disagreement with conventio nal modelling assumptions. Investigations based on PHREEQC reactive modelling and both scanning electron microscopy (SEM) and PIXE / RBS analysis (nuclear microprobe) proved that Zn and Cd did not precipitate separately as smithsonite and otavite as usually ob served under these experimental conditions. These investigations point at a surface substitution proc ess in which Ca is successively replaced by metals s uch as Zn and Cd on surface sites, followed by diffusion of th ese metals into the lattice of the calcareous parti cles.
Geochimica et Cosmochimica Acta, 2009
Geochimica et Cosmochimica Acta, 2010
Earth and Planetary Science Letters, 2014
Earth and Planetary Science Letters, 2014
ABSTRACT The mechanism and magnitude of fluorine incorporation in H-bearing forsterite were inves... more ABSTRACT The mechanism and magnitude of fluorine incorporation in H-bearing forsterite were investigated through a combined experimental and theoretical approach. Forsterite samples were synthesized in a piston cylinder press at 2 and 4 GPa, in hydrous conditions, with or without fluorine. High fluorine solubilities of 1715 and 1308 ppm F were measured by particle induced gamma-ray emission (PIGE) in forsterite samples synthesized at 2 and 4 GPa, respectively. In addition, first-principles calculations based on density functional theory were performed in order to investigate the coupled incorporation mechanisms of fluorine and water in forsterite. Our results demonstrate the close association of fluoride, hydroxyl groups and Si vacancies. Comparison of experimental and theoretical infrared absorption spectra enables assignment of the nine OH stretching bands (3500–3700 cm−1) observed in F-rich synthetic forsterite to clumped fluoride-hydroxyl defects in the forsterite crystal structure. Noteworthily, similar bands were previously recorded on some natural olivine with Mg/(Mg+Fe) molar ratio down to 0.86. Fluorine and water cycles are therefore strongly coupled through the nominally anhydrous minerals and the mantle fluorine budget can be entirely accommodated by these mineral phases.
Chemical Geology, 2009
... The most common absolute methods used to quantify hydrogen in glasses or minerals are manomet... more ... The most common absolute methods used to quantify hydrogen in glasses or minerals are manometry (eg, [Dobson et al., 1989] and [Bell et al., 1995]), Karl-Fisher titration (KFT) (eg,Behrens et al., 1996), nuclear reaction analysis (eg, Bell et al., 2003) and elastic recoil ...
Chemical Geology, 2012
ABSTRACT Elastic recoil detection analysis (ERDA) was used to measure the H contents of 18 synthe... more ABSTRACT Elastic recoil detection analysis (ERDA) was used to measure the H contents of 18 synthetic Fo(90) olivines that had been hydrated to varying degrees in high pressure hydrothermal experiments. The infrared spectra of the olivines have been previously measured in the OH stretching region by Fourier transform infrared spectroscopy, and (OH)-O-16-H-1 secondary ion mass spectroscopy measurements have been made on the same samples. Mapping by ERDA, Rutherford backscattering and particle induced X-ray emission spectroscopies show that the synthetic olivines are homogeneous with respect to major element and H concentrations. Concentrations of H measured by ERDA vary between 270 and 2120 ppm H2O. Measurements of OH/Si ratios by secondary ion mass spectroscopy and of total integrated area of OH stretching bands in principal absorption spectra by FTIR show excellent linear relationships to H concentrations determined by ERDA. The ERDA measurements are used to determine an infrared integral molar absorption coefficient of 45,200 I mol(-1) cm(-2) that can be used to determine H contents of olivines from high pressure experiments. The H content of Fo(90) olivines (in wt. ppm H2O) is given by 0.119 +/- 0.006 x total integrated absorbance per cm thickness. (C) 2012 Elsevier B.V. All rights reserved.
Solid State Phenomena, 2011