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1. Electronic emission of radio-sensitizing gold nanoparticles under X-ray irradiation : experiment and simulations

Author

Casta, R., Champeaux, J. -P., Sence, M., Moretto-Capelle, P., Cafarelli, P., Amsellem, A., and Sicard-Roselli, C.

Subjects
Physics - Atomic Physics, Condensed Matter - Materials Science
Abstract

In this paper we present new results on electronic emission of Gold Nanoparticles (GNPs) using X-ray photoelectron spectroscopy (XPS) and compare them to the gold bulk electron emission. This subject has undergone new interest within the perspective of using GNPs as a radiotherapy enhancer. The experimental results were simulated using various models (Livermore and PENELOPE) of the Geant 4 simulation toolkit dedicated to the calculation of the transportation of particles through the matter. Our results show that the GNPs coating is a key parameter to correctly construe the experimental GNPs electronic emission after X-ray irradiation and point out some limitations of the PENELOPE model. Using XPS spectra and Geant4 Livermore simulations,we propose a method to determine precisely the coating surface density of the GNPs. We also show that the expected intrinsic nano-scale electronic emission enhancement effect - suspected to contribute to the GNPs radio-sensitizing properties - participates at most for a few percent of the global electronic emission spectra of the GNPs compared to gold bulk., Comment: Journal: Journal of Nanoparticle Research Vol. 16,4 2014

Published
2014
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2. Model for electron emission of high-Z radio-sensitizing nanoparticle irradiated by X-rays

Author

Casta, R., Champeaux, J. -P., Sence, M., Moretto-Capelle, P., and Cafarelli, P.

Subjects
Physics - Atomic Physics, Condensed Matter - Materials Science
Abstract

In this paper we develop a new model for the electron emission of high-Z nanoparticle irradiated by X-rays. This study is motivated by the recent advances about the nanoparticle enhancement of cancer treatment by radiotherapy. Our original approach combines a pure probabilistic analytical model for the photon trajectories inside the nanoparticle and subsequent electron cascade trajectories based here on a Monte-Carlo simulation provided by the Livermore model implemented in Geant4. To compare the nanoparticle and the plane surface electron emissions, we also develop our model for a plane surface. Our model highlights and explains the existence of a nanoparticle optimal radius corresponding to a maximum of nanoparticle electron emission. It allows us to study precisely the nanoparticle photon absorption and electron cascade production depth in the nanoparticle.

Published
2014
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3. Laser-induced electron emission from a tungsten nanotip: identifying above threshold photoemission using energy-resolved laser power dependencies

Author

Bionta, M. R., Chalopin, B., Champeaux, J. P., Faure, S., Masseboeuf, A., Moretto-Capelle, P., and Chatel, B.

Subjects
Physics - Optics, Physics - Atomic Physics
Abstract

We present an experiment studying the interaction of a strongly focused 25 fs laser pulse with a tungsten nanotip, investigating the different regimes of laser-induced electron emission. We study the dependence of the electron yield with respect to the static electric field applied to the tip. Photoelectron spectra are recorded using a retarding field spectrometer and peaks separated by the photon energy are observed with a 45 % contrast. They are a clear signature of above threshold photoemission (ATP), and are confirmed by extensive spectrally resolved studies of the laser power dependence. Understanding these mechanisms opens the route to control experiment in the strong-field regime on nanoscale objects., Comment: 9 pages, 6 figures

Published
2013
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5. Electron-induced ionization and cationic fragmentations of the isolated molecule of 2,4-imidazolidinedione (hydantoin): a study of the relaxing path thresholds

Author

Champeaux, J.-P., primary, Moretto-Capelle, P., additional, Renoud, J., additional, Polizzi, L., additional, Faure, S., additional, Castex, D., additional, Gianesin, M., additional, Panader, E., additional, Paquier, P., additional, Volondat, W., additional, Salbaing, T., additional, Riffaud, J., additional, Point, R., additional, Cafarelli, P., additional, and Sence, M., additional

Published
2023
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9. Absolute measurements of the double differential electronic emission cross-sections of isolated pyrene molecule (C16H10) in interaction with keV protons.

Author

Ji, M-C, Champeaux, J-P, Moretto-Capelle, P, Renoud, J, Polizzi, L, Faure, S, Sence, M, and Cafarelli, P

Subjects
*PROTON-proton interactions, *PROTON beams, *MOLECULES, *MEASUREMENT, *PROTONS
Abstract

Electronic emission of an isolated pyrene molecule induced by 50 to 125 keV protons has been investigated. The corresponding absolute double differential cross-sections have been measured at an angle of 35° with respect to the incident proton beam axis. These measurements were compared to the simulations of emitted electrons' spectra using a semi-classical trajectory Monte-Carlo (SCTMC) approach. The simulated SCTMC cross-sections show reasonably good agreement with the measured ones. [ABSTRACT FROM AUTHOR]

Published
2020
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10. Time-dependent density functional theory molecular dynamics simulation of doubly charged uracil in gas phase

Author

López-Tarifa P., Hervé du Penhoat M.-A., Vuilleumier R., Gaigeot M.-P., Rothlisberger U., Tavernelli I., Le Padellec A., Champeaux J.-P., Alcamí M., Moretto-Capelle P., Martín F., Politis M.-F. and This paper was intended for the special issue associated to the annual meeting of the COST Action CM0702 held in Cluj-Napoca, Romania between 21-23 March 2012. This work was performed using HPC resources from Mare Nostrum BSC, CCC-UAM, CCR UPMC and GENCI - CINES/IDRIS grant 2010-085014. We thank the support of the MICINN projects FIS2010-15127, CTQ2010-17006, ACI2008-0777, and CSD 2007-00010, the CAM project S2009/MAT1726, the COST Action CM0702, the Picasso project HF2007-0067, and HPC Europa2. P. López-Tarifa, I. Tavernelli and U. Röthlisberger also acknowledge the Swiss NSF through the NCCR MUST interdisciplinary research program. P. López-Tarifa also thanks the FP7 Marie Curie COFUND Action.

Published
2014

16. Time-dependent density functional theory molecular dynamics simulation of doubly charged uracil in gas phase

Author

López-Tarifa P., Hervé du Penhoat M.-A., Vuilleumier R., Gaigeot M.-P., Rothlisberger U., Tavernelli I., Le Padellec A., Champeaux J.-P., Alcamí M., Moretto-Capelle P., Martín, Fernando, Politis M.-F., López-Tarifa P., Hervé du Penhoat M.-A., Vuilleumier R., Gaigeot M.-P., Rothlisberger U., Tavernelli I., Le Padellec A., Champeaux J.-P., Alcamí M., Moretto-Capelle P., Martín, Fernando, and Politis M.-F.

Published
2014

17. Absolute photoionization cross sections for highly charged iron and xenon ions

Author

Bizau, J. M., Cubaynes, D., Wuilleumier, Fj, Blieck, J., Blancard, C., Champeaux, J. P., Faussurier, G., Lemaire, Jl, Luna, H., Kilbane, D., Folkmann, F., Laboratoire d'interaction du rayonnement X avec la matière (LIXAM), and Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-ATOM-PH]Physics [physics]/Physics [physics]/Atomic Physics [physics.atom-ph]
Published
2006

19. Absolute photoionization cross sections along the Xe isonuclear sequence : Xe3+ to Xe6+

Author

Bizau, J. M., Blancard, C., Champeaux, J. P., Cubaynes, D., Folkmann, F., Lemaire, Jl, Wuilleumier, Fj, Laboratoire d'interaction du rayonnement X avec la matière (LIXAM), and Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-ATOM-PH]Physics [physics]/Physics [physics]/Atomic Physics [physics.atom-ph], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2006

20. Absolute photoionization cross sections for N3+, O4+, F3+ and Ne4+

Author

Bizau, J. M., Blancard, C., Champeaux, J. P., Cubaynes, D., Folkmann, F., Jacobsen, Ts, Kjeldsen, H., Penent, F., Wuilleumier, Fj, Laboratoire d'interaction du rayonnement X avec la matière (LIXAM), and Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-ATOM-PH]Physics [physics]/Physics [physics]/Atomic Physics [physics.atom-ph]
Published
2005

21. Absolute cross sections ofr L-shell photoionization of the ions N2+, N33+,O3+, O4+, F3+, F4+ and Ne4+

Author

Bizau, J. M., Blancard, C., Champeaux, J. P., Cubaynes, D., Folkmann, F., Jacobsen, Ts, Kjeldsen, H., Penent, F., Wuilleumier, Fj, Laboratoire d'interaction du rayonnement X avec la matière (LIXAM), and Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-ATOM-PH]Physics [physics]/Physics [physics]/Atomic Physics [physics.atom-ph], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2005

26. Absolute photoionization cross sections and resonance structure of doubly ionized silicon in the region of the 2p-1 threshold: Experiment and theory

Author

Mosnier, J.-P., Sayyad, M.H., Kennedy, E.T., Bizau, J.-M., Cubaynes, D., Wuilleumier, F.J., Champeaux, J.-P., Blancard, C., Hari Varma, R., Banerjee, T., Deshmukh, P.C., Manson, S.T.

Subjects
Approximation theory, Computer simulation, Crystal atomic structure, Data reduction, Electron cyclotron resonance, Electron energy levels, Light absorption, Optical resolving power, Photons, Positive ions, Quantum theory, Silicon, Spectrometry, Synchrotron radiation, Multi-channel quantum defect theory, Multiconfiguration atomic structure, Photon energy, Relativistic random-phase approximation (RRPA), Photoionization
Abstract

The absolute photoionization cross sections of doubly ionized silicon in the ground state as a function of photon energy in the region of 2p threshold (95eV-170eV) was presented. The cross sectional values contained a small contribution from metastable Si2+ that did not exceed 3%. The relativistic random-phase approximation (RRPA) was used to calculate the 2p photoionization continuum cross sections and agreed well with the corresponding measurements. It was found that the satellite transitions play an important role in the photoionization of Si2+.

Published
2003

27. Absolute photoionization cross sections and resonance structure of doubly ionized silicon in the region of the 2p-1 threshold: experiment and theory

Author

Mosnier, Jean-Paul, Sayyad, Muhammad Hassan, Kennedy, Eugene T., Bizau, J.-M., Cubaynes, D., Wuilleumier, F., Champeaux, J.-P., Blancard, C., Varma, R., Banerjee, T., Deshmukh, P., and Manson, S.

Subjects
Physics, Physics::Atomic Physics
Abstract

We present the absolute photoionization cross section of doubly ionized silicon as a function of photon energy. These were obtained by merging a Si2+ ion beam generated in an electron cyclotron resonance source with monochromatized synchrotron radiation from an undulator. The photoion yield measurements were carried out in the photon energy range between 95 eV and 170 eV, i.e., the region corresponding to the excitation followed by the ionization (threshold ∼133.8eV) of an inner-subshell 2p electron. Resonance structure due to 2p excitation in the 2p63s3p3P metastable state was also observed with its contribution to the total cross section not exceeding 3%. Calculation of the 2p photoionization continuum cross section as a function of photon energy was carried out using the relativistic random-phase approximation (RRPA) and agreed very well with the corresponding measurements. The resonance structure in the 3s cross section below the 2p threshold was found to be in good agreement with the multiconfiguration atomic structure calculations of Sayyad et al. [J. Phys. B 28, 1715 (1995)], while the corresponding RRPA-RMQDT (relativistic multi-channel quantum-defect theory) calculations proved less successful.

Published
2003

28. Ultrafast non-adiabatic fragmentation dynamics of doubly charged uracil in gas and liquid phase

Author

López-Tarifa P., Penhoat M.-A.H.D., Vuilleumier R., Gaigeot M.-P., Tavernelli I., Padellec A.L., Champeaux J.-P., Alcamí M., Moretto-Capelle P., Martín, Fernando, Politis M.-F., López-Tarifa P., Penhoat M.-A.H.D., Vuilleumier R., Gaigeot M.-P., Tavernelli I., Padellec A.L., Champeaux J.-P., Alcamí M., Moretto-Capelle P., Martín, Fernando, and Politis M.-F.

Published
2012

29. Ultrafast nonadiabatic fragmentation dynamics of doubly charged uracil in a gas phase

Author

López-Tarifa P., Hervé Du Penhoat M.-A., Vuilleumier R., Gaigeot M.-P., Tavernelli I., Le Padellec A., Champeaux J.-P., Alcamí M., Moretto-Capelle P., Martín, Fernando, Politis M.-F., López-Tarifa P., Hervé Du Penhoat M.-A., Vuilleumier R., Gaigeot M.-P., Tavernelli I., Le Padellec A., Champeaux J.-P., Alcamí M., Moretto-Capelle P., Martín, Fernando, and Politis M.-F.

Published
2011

30. Photoionization of the Ne-like Si4+ ion in ground and metastable states in the 110- 84-eV photon energy range.

Author

Bizau, J.-M., Mosnier, Jean-Paul, Kennedy, Eugene T., Cubaynes, D., Wuilleumier, F., Blancard, C., Champeaux, J.-P., Folkmann, F., Bizau, J.-M., Mosnier, Jean-Paul, Kennedy, Eugene T., Cubaynes, D., Wuilleumier, F., Blancard, C., Champeaux, J.-P., and Folkmann, F.

Abstract

P0,2 metastable levels were observed. Calculations of the 2p photoionization cross sections were carried out using a multi-configuration Dirac-Fock code. They give results in good agreement with the measured spectra. Comparison with other available theoretical results is also presented.

Published
2009

31. Photoionization of the Ne-like Si4+ ion in ground and metastable states in the 110–184-eV photon energy range

Author

Bizau, J.-M., Mosnier, Jean-Paul, Kennedy, Eugene T., Cubaynes, D., Wuilleumier, F., Blancard, C., Champeaux, J.-P., Folkmann, F., Bizau, J.-M., Mosnier, Jean-Paul, Kennedy, Eugene T., Cubaynes, D., Wuilleumier, F., Blancard, C., Champeaux, J.-P., and Folkmann, F.

Abstract

We present measurements of the absolute photoionization cross section of the neonlike Si4+ ion over the 110–184 eV photon energy range. The measurements were performed using two independent merged-beam setups at the super-ACO and ASTRID synchrotron-radiation facilities, respectively. Signals produced in the photoionization of the 2p subshell of the Si4+ ion both from the 2p6 1S0 ground state and the 2p53s 3P0,2 metastable levels were observed. Calculations of the 2p photoionization cross sections were carried out using a multi-configuration Dirac-Fock code. They give results in good agreement with the measured spectra. Comparison with other available theoretical results is also presented.

Published
2009

40. Absolute photoionization cross sections and resonance structure of doubly ionized silicon in the region of the2p−1threshold: Experiment and theory

Author

Mosnier, J.-P., primary, Sayyad, M. H., additional, Kennedy, E. T., additional, Bizau, J.-M., additional, Cubaynes, D., additional, Wuilleumier, F. J., additional, Champeaux, J.-P., additional, Blancard, C., additional, Varma, R. Hari, additional, Banerjee, T., additional, Deshmukh, P. C., additional, and Manson, S. T., additional

Published
2003
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42. Systèmes d'imagerie à haute résolution dans le domaine des Rayons X pour le Laser Mégajoule

Author

Champeaux, J.-Ph., Troussel, Ph., Boutin, J.-Y., Lidove, G., Marmoret, R., Soullié, G., Rosch, R., Champeaux, J.-Ph., Troussel, Ph., Boutin, J.-Y., Lidove, G., Marmoret, R., Soullié, G., and Rosch, R.

Abstract

Le principe de la fusion par confinement inertiel consiste à faire imploser une cible sphérique de petite taille, millimétrique, remplie d'un mélange de deutérium et de tritium sous l'action des 240 faisceaux lasers impulsionnels de très grande puissance du LMJ. Les études de cette physique d'implosion (mise en vitesse, symétrie d'implosion, instabilités hydrodynamiques) et de l'allumage (traceurs, point chaud) font appel aux techniques de l'imagerie et de la radiographie à haute résolution spatiale ($\mu{\rm m}$) et temporelle (ps) avec sélection spectrale dans le domaine d'énergie de photons comprise entre $100\,{\rm eV}$et $20\,{\rm keV}$. Plusieurs Systèmes d'Imagerie X(SIX), à haute résolution spatiale, ont donc été développés par le CEA-DIF et mis en œuvre sur la Ligne d'Intégration Laser (LIL) implantée au CEA-CESTA. Dans cet article nous présentons lesprincipaux SIX, à base de microscopes à miroirs. Un exemple de microscope prototype nommé PIXEL (Plasma Imageur Xpour les Expériences Lasers) développé pour le LMJ est présenté. Nous portons l'accent sur les problèmes technologiques liés à l'environnement LMJ.

Published
2006
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43. Absolute Measurements and MCDF Calculation of the Photoionization Cross Section of O3+ Ion.

Author

Champeaux, J.-P., Bizau, J.-M., Cubaynes, D., Blancard, C., Hitz, D., Bruneau, J., and Wuilleumier, F. J.

Subjects
*PHOTOIONIZATION, *OXYGEN
Abstract

In this paper, we present the results of our investigation on the photoionization of the O[sup 3+] ion in the 1s²2s²2p ²p ground state and the 1 s²2s2p² [sup 4]P metastable states. The experimental results are compared to a 72-states Multi Configurational Dirac Fock (MCDF) calculation. [ABSTRACT FROM AUTHOR]

Published
2003

44. Absolute cross sections for L-shell photoionization of the ions N$\mathsf{^{2+}}$, N$\mathsf{^{3+}}$, O$\mathsf{^{3+}}$, O$\mathsf{^{4+}}$, F$\mathsf{^{3+}}$, F$\mathsf{^{4+}}$and Ne$\mathsf{^{4+}}$

Author

Bizau, J.-M., Champeaux, J.-P., Cubaynes, D., Wuilleumier, F. J., Folkmann, F., Jacobsen, T. S., Penent, F., Blancard, C., Kjeldsen, H., Bizau, J.-M., Champeaux, J.-P., Cubaynes, D., Wuilleumier, F. J., Folkmann, F., Jacobsen, T. S., Penent, F., Blancard, C., and Kjeldsen, H.

Abstract

Absolute photoionization cross sections for the ions N2+, N3+, O3+, O4+, F3+, F4+and Ne4+are measured using the merged-beam technique, combining the synchrotron radiation from an undulator at the storage ring ASTRID with ions produced by an ECR ion source. The spectral structures and the development of the cross sections along iso-electronic sequences are discussed. The experimental data are compared with R-matrix calculations from the Opacity Project and other sources, MCDF calculations, as well as the model functions provided by verner et al. (1996). In general, good agreement between experiment and calculations is observed for the magnitude of the continuum cross sections whereas very significant discrepancies are present for the resonance structures. The experimental data are also available in electronic form at the CDS.

Published
2005
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45. Absolute Measurements and Theoretical Calculations of Photoionization Cross Sections along the Isonuclear Sequence of Multiply Charged Barium Ions

Author

Bizau, J.-M., primary, Cubaynes, D., additional, Esteva, J.-M., additional, Wuilleumier, F. J., additional, Blancard, C., additional, Bruneau, J., additional, Champeaux, J.-P., additional, Compant La Fontaine, A., additional, Couillaud, C., additional, Marmoret, R., additional, Rémond, C., additional, Hitz, D., additional, Delaunay, M., additional, Haque, N., additional, Deshmukh, P. C., additional, Zhou, H. L., additional, and Manson, S. T., additional

Published
2001
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46. Syst?mes d'imagerie ? haute r?solution dans le domaine des Rayons X pour le Laser M?gajoule

Author

Champeaux, J.-Ph., Troussel, Ph., Boutin, J.-Y., Lidove, G., Marmoret, R., Soulli?, G., and Rosch, R.

Abstract

Le principe de la fusion par confinement inertiel consiste ? faire imploser une cible sph?rique de petite taille, millim?trique, remplie d'un m?lange de deut?rium et de tritium sous l'action des 240 faisceaux lasers impulsionnels de tr?s grande puissance du LMJ. Les ?tudes de cette physique d'implosion (mise en vitesse, sym?trie d'implosion, instabilit?s hydrodynamiques) et de l'allumage (traceurs, point chaud) font appel aux techniques de l'imagerie et de la radiographie ? haute r?solution spatiale (?m) et temporelle (ps) avec s?lection spectrale dans le domaine d'?nergie de photons comprise entre 100eV et 20keV. Plusieurs Syst?mes d'Imagerie X (SIX), ? haute r?solution spatiale, ont donc ?t? d?velopp?s par le CEA-DIF et mis en ?uvre sur la Ligne d'Int?gration Laser (LIL) implant?e au CEA-CESTA. Dans cet article nous pr?sentons les principaux SIX, ? base de microscopes ? miroirs. Un exemple de microscope prototype nomm? PIXEL (Plasma Imageur X pour les Exp?riences Lasers) d?velopp? pour le LMJ est pr?sent?. Nous portons l'accent sur les probl?mes technologiques li?s ? l'environnement LMJ.

Published
2006

47. ECOCLIMAP: a global database of land surface parameters at 1 km resolution

Author

Champeaux, J. L., Masson, V., and Chauvin, F.

Abstract

Soil/vegetation–atmosphere transfer schemes (SVATS) require only a few primary parameters as inputs (leaf area index, vegetation fraction and albedo). The object of this paper is to describe methods used to derive these parameters from surface cover maps, climate maps and NDVI datasets. The resolution of these new surface parameters is 1 km at the global scale. The ECOCLIMAP database is available online to the research community at . An application of this strategy for urban use at a finer scale (30mresolution) is presented here for the city of Marseille. Copyright © 2005 Royal Meteorological Society.

Published
2005
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