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5 results on '"Julie AUFORT"'

1. Modeling the attenuated total reflectance infrared (ATR-FTIR) spectrum of apatite

Author

Etienne Balan, Christian Brouder, Loïc Ségalen, Julie Aufort, Christel Gervais, Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Biominéralisations et environnements sédimentaires (BES), Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Spectroscopie, Modélisation, Interfaces pour L'Environnement et la Santé (SMiLES), Laboratoire de Chimie de la Matière Condensée de Paris (LCMCP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Collège de France (CdF (institution))-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Collège de France (CdF (institution))-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Labex Matisse, ANR-11-IDEX-0004,SUPER,Sorbonne Universités à Paris pour l'Enseignement et la Recherche(2011), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Collège de France (CdF (institution))-Institut de Chimie du CNRS (INC)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Collège de France (CdF (institution))-Institut de Chimie du CNRS (INC)

Subjects
Infrared, Analytical chemistry, Physics::Optics, Infrared spectroscopy, Effective medium, Bruggeman model, 02 engineering and technology, 010502 geochemistry & geophysics, 01 natural sciences, Apatite, Geochemistry and Petrology, General Materials Science, Fourier transform infrared spectroscopy, 0105 earth and related environmental sciences, [PHYS]Physics [physics], Chemistry, Fluorapatite, [CHIM.MATE]Chemical Sciences/Material chemistry, Fresnel equations, 021001 nanoscience & nanotechnology, Wavelength, visual_art, Attenuated total reflection, visual_art.visual_art_medium, Attenuated total reflectance, 0210 nano-technology, ATR-FTIR, [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy
Abstract

International audience; Attenuated total reflectance (ATR) infrared spectra were measured on a synthetic and a natural fluorapatite sample. A modeling approach based on the computation of the Fresnel reflection coefficient between the ATR crystal and the powder sample was used to analyze the line shape of the spectra. The dielectric properties of the samples were related to those of pure fluorapatite using an effective medium approach, based on Maxwell–Garnett and Bruggeman models. The Bruggeman effective medium model leads to a very good agreement with the experimental data recorded on the synthetic fluorapatite sample. The poorer agreement observed on the natural sample suggests a more significant heterogeneity of the sample at a characteristic length scale larger than the mid-infrared characteristic wavelength, i.e., about 10 micrometers. The results demonstrate the prominent role of macroscopic electrostatic effects over fine details of the microscopic structure in determining the line shape of strong ATR bands.

Published
2016
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2. Line-broadening and anharmonic effects in the attenuated total reflectance infrared spectra of calcite

Author

Etienne Balan, Julie Aufort, Michele Lazzeri, Christian Brouder, Giuseppe D. Saldi, Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Cluster of Excellence MATISSE led by Sorbonne UniversitésCARBORIC (ANR-13-BS06-0013-06), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
Calcite, Materials science, Anharmonicity, Analytical chemistry, Infrared spectroscopy, 02 engineering and technology, multi-phonon, 021001 nanoscience & nanotechnology, 01 natural sciences, effective medium, chemistry.chemical_compound, ATR, chemistry, Geochemistry and Petrology, Attenuated total reflection, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 010306 general physics, 0210 nano-technology, infrared spectroscopy, calcite, Line (formation), [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy
Abstract

International audience; The attenuated total reflectance (ATR) spectra of two calcite samples have been measured using Ge and diamond internal reflection elements. One of the samples was obtained by precipitation from solution and displays sub-micrometer sized particles. The second sample was obtained by grinding a single-crystal of calcite (''Iceland spar'' variety). Theoretical spectra were obtained by computing the reflection coefficient of the interface between the ATR internal reflection element and a homogeneous effective medium representing the powder sample. The dielectric properties of the effective medium have been determined from those of bulk calcite using the Bruggeman approach which is adequate for standard powders with intermediate fractions of solid and empty porosity. Although this modeling approach provides a quantitative interpretation of the broadening of strong absorption bands in the calcite ATR spectra, it fails to reproduce the apparent splitting of the strong nu3 CO3 band. This problem was solved by combining the electrostatic modeling approach with a semi-quantum model of the dielectric tensor of bulk calcite, which allows for a frequency-dependent damping of the nu3 CO3 excitation. The frequency-dependence is ascribed to a multiphonon-related resonance in the nu3 CO3 phonon self-energy at a frequency close to its transverse optical frequency. The combination of approaches exposed in the present study makes it possible to discriminate among physically different processes affecting the powder infrared spectra of calcite, some being related to the long-range nature of electrostatic interactions in polar materials and others being related to atomic-scale anharmonic interactions between vibrational modes.

Published
2019
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3. Unraveling weathering episodes in Tertiary regoliths by kaolinite dating (Western Ghats, India)

Author

Julie Aufort, Jean-Jacques Braun, Etienne Balan, Thierry Allard, Madeleine Selo, Maximilien Mathian, Jean Riotte, Shrema Bhattacharya, Emmanuel Fritsch, Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Physical Research Laboratory [Ahmedabad] (PRL), Indian Space Research Organisation (ISRO), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)

Subjects
geography, Plateau, geography.geographical_feature_category, Indian monsoon, 010504 meteorology & atmospheric sciences, Weathering, Geochemistry, Geology, Forcing (mathematics), Laterite, 010502 geochemistry & geophysics, Monsoon, 01 natural sciences, Regolith, EPR dating, 13. Climate action, Kaolinite, Erosion, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, 0105 earth and related environmental sciences, [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy
Abstract

International audience; Secondary minerals in soils can record climatic changes affecting continental surfaces over geological times. Their dating should refine our present knowledge about their potential periods of formation as well as their relations with the ongoing change of climate and erosion/weathering regimes. In the present study, twenty kaolinite samples from two lateritic profiles of the Karnataka plateau, an intensively studied area in the southern India, have been dated using electron paramagnetic resonance (EPR) spectroscopy. Kaolinite ages vary between 0.229±0.24 Ma to 40.73±15.37 Ma. Four different groups of age can be identified with ages clustered around 1.0, 3.5, 9.0 and 39.0 Ma. These groups of age indicate local preferential weathering periods that coincide with distinct Indian climatic events described in independent studies, such as monsoon strengthening. Thus, regional or subcontinental factors likely prevailed over global forcing in the imprint of climatic events in the regolith profiles. These results confirm that despite their simple mineralogy, laterites can contain several relictual and coexisting generations of secondary minerals and that EPR dating of kaolinite contributes to unraveling the complex history of continental surfaces over geological periods.

Published
2019
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4. Macroscopic electrostatic effects in ATR-FTIR spectra of modern and archeological bones

Author

Xavier Gallet, Loïc Ségalen, Julie Aufort, Christian Brouder, Christel Gervais, Etienne Balan, Matthieu Lebon, Institut de minéralogie, de physique des matériaux et de cosmochimie ( IMPMC ), Muséum National d'Histoire Naturelle ( MNHN ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique ( CNRS ), Histoire naturelle de l'Homme préhistorique ( HNHP ), Muséum National d'Histoire Naturelle ( MNHN ) -Université de Perpignan Via Domitia ( UPVD ) -Centre National de la Recherche Scientifique ( CNRS ), Biominéralisations et environnements sédimentaires ( BES ), Institut des Sciences de la Terre de Paris ( iSTeP ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ), Spectroscopie, Modélisation, Interfaces pour L'Environnement et la Santé ( SMiLES ), Laboratoire de Chimie de la Matière Condensée de Paris ( LCMCP ), Centre National de la Recherche Scientifique ( CNRS ) -Collège de France ( CdF ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ) -Collège de France ( CdF ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Histoire naturelle de l'Homme préhistorique (HNHP), Muséum national d'Histoire naturelle (MNHN)-Université de Perpignan Via Domitia (UPVD)-Centre National de la Recherche Scientifique (CNRS), Biominéralisations et environnements sédimentaires (BES), Institut des Sciences de la Terre de Paris (iSTeP), Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS), Spectroscopie, Modélisation, Interfaces pour L'Environnement et la Santé (SMiLES), Laboratoire de Chimie de la Matière Condensée de Paris (LCMCP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Collège de France (CdF (institution))-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Collège de France (CdF (institution))-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC), Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Université de Perpignan Via Domitia (UPVD), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Collège de France (CdF)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Collège de France (CdF)-Centre National de la Recherche Scientifique (CNRS), and Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS)

Subjects
fossilization, 010506 paleontology, Materials science, Enamel paint, ATR-FTIR spectroscopy, Atr ftir spectroscopy, Infrared spectroscopy, electrostatic properties, 010502 geochemistry & geophysics, 01 natural sciences, bone, Apatite, Diagenesis, Ftir spectra, Biomaterials, Geophysics, Geochemistry and Petrology, visual_art, visual_art.visual_art_medium, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, [ SDU.STU.MI ] Sciences of the Universe [physics]/Earth Sciences/Mineralogy, 0105 earth and related environmental sciences, Nuclear chemistry, [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy, [ SDU.STU.PG ] Sciences of the Universe [physics]/Earth Sciences/Paleontology
Abstract

International audience; Bones mostly consist of composite materials based on almost equivalent volume fractions of mineral (apatite) and organic (collagen) components. Accordingly, their infrared spectroscopic properties should reflect this composite nature. In this letter, we show by theory and experiment that the variability of the strong phosphate bands in the ATR-FTIR spectra of a series of modern and archeological bone samples can be related to electrostatic interactions affecting apatite particles and depending on the bone collagen content. Key parameters controlling the shape of these bands are the mineral volume fraction and the dielectric constant of the embedding matrix. The magnitude of these effects is larger than the one related to microscopic changes of the apatite structure. Consequently, the interplay of microscopic and macroscopic parameters should be considered when using FTIR spectroscopy to monitor the preservation state of bioapatite during diagenetic and fossilization processes, especially during the degradation of the organic fraction of bone.

Published
2018
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5. Infrared spectroscopic study of sulfate-bearing calcite from deep-sea bamboo coral

Author

Sophie Pouillé, Julie Aufort, Marc Blanchard, Michele Lazzeri, D. Blamart, Etienne Balan, Marie Dabos, Claire Rollion-Bard, Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Paléocéanographie (PALEOCEAN), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)

Subjects
Calcite, 010504 meteorology & atmospheric sciences, biology, Infrared, Analytical chemistry, Diamond, Infrared spectroscopy, Mineralogy, engineering.material, 010502 geochemistry & geophysics, biology.organism_classification, 01 natural sciences, Thermal expansion, chemistry.chemical_compound, Bamboo coral, chemistry, Geochemistry and Petrology, Attenuated total reflection, engineering, Sulfate, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy
Abstract

The powder infrared spectra of a sulfate-bearing calcitic coral sample are recorded at room temperature in attenuated total reflectance (ATR) geometry and at low temperature in transmission geometry. The comparison of ATR spectra recorded with diamond or Ge crystal confirms that the width and the shape of the prominent absorption bands, related to CO 3 groups, are dominantly affected by macroscopic electrostatic interactions. In contrast, the temperature-dependence of the position and width of weak and narrow absorption bands, related to CO 3 or SO 4 groups, can be interpreted in terms of thermal expansion, anharmonic coupling, and local strain fluctuations. The three SO 4 stretching bands display a contrasted thermal behavior, the frequency of one of them increasing with temperature. Based on first-principles calculation, this unusual temperature dependence is traced back to the anisotropy of calcite thermal expansion. These results sustain the previously proposed atomic-scale model of sulfate in calcite and attest to a dominantly structural nature of sulfate in the investigated sample. Accordingly, structurally substituted sulfur in deep-sea calcitic bamboo coral could be used as proxy of seawater sulfate.

Published
2017
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