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7 results on '"Sophie Hameau"'

1. Deterministic placement of ultra-bright near-infrared color centers in arrays of silicon carbide micropillars

Author

Stefania Castelletto, Abdul Salam Al Atem, Faraz Ahmed Inam, Hans Jürgen von Bardeleben, Sophie Hameau, Ahmed Fahad Almutairi, Gérard Guillot, Shin-ichiro Sato, Alberto Boretti, and Jean Marie Bluet

Subjects
color centers, micropillars, proton irradiation, quantum sensing, silicon carbide, vacancy, Technology, Chemical technology, TP1-1185, Science, Physics, QC1-999
Abstract

We report the enhancement of the optical emission between 850 and 1400 nm of an ensemble of silicon mono-vacancies (VSi), silicon and carbon divacancies (VCVSi), and nitrogen vacancies (NCVSi) in an n-type 4H-SiC array of micropillars. The micropillars have a length of ca. 4.5 μm and a diameter of ca. 740 nm, and were implanted with H+ ions to produce an ensemble of color centers at a depth of approximately 2 μm. The samples were in part annealed at different temperatures (750 and 900 °C) to selectively produce distinct color centers. For all these color centers we saw an enhancement of the photostable fluorescence emission of at least a factor of 6 using micro-photoluminescence systems. Using custom confocal microscopy setups, we characterized the emission of VSi measuring an enhancement by up to a factor of 20, and of NCVSi with an enhancement up to a factor of 7. The experimental results are supported by finite element method simulations. Our study provides the pathway for device design and fabrication with an integrated ultra-bright ensemble of VSi and NCVSi for in vivo imaging and sensing in the infrared.

Published
2019
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2. Adaptations of fatigue and fatigability after a short intensive, combined rehabilitation program in patients with multiple sclerosis

Author

Sophie Hameau, Djamel Bensmail, Nicolas Roche, and Raphael Zory

Subjects
musclefatigue, quadricepsmuscle, rehabilitation, endurancetraining, resistancetraining, isokineticassessment., Therapeutics. Pharmacology, RM1-950
Abstract

Objective: Fatigue and fatigability are common problems in patients with multiple sclerosis, which might be improved by rehabilitation. The aim of this pilot study was to assess changes in the fatigue and fatigability of knee extensors in patients with multiple sclerosis after a short intensive, combined rehabilitation programme (including physiotherapy primarily focused on gait and balance, endurance and resistance training). Methods: Twenty-three patients with multiple sclerosis (10 men, 13 women) underwent isokinetic evaluations of fatigability of the knee extensor muscles during concentric contractions and rated a self-reported fatigue scale (Modified Fatigue Impact Scale; MFIS) before and after a rehabilitation programme. Patients performed rehabilitation for 150 min, 4 days per week for 4 weeks, with physiotherapy focused primarily on gait and balance, endurance training and resistance training. Results: After rehabilitation, perception of fatigue decreased significantly (median MFIS scores [1st; 3rd quartiles], pre: 44 [33; 53] vs post: 33.5 [16; 43];

Published
2017
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3. Coactivation of Lower Limb Muscles during Gait in Patients with Multiple Sclerosis.

Author

Julien Boudarham, Sophie Hameau, Raphael Zory, Alexandre Hardy, Djamel Bensmail, and Nicolas Roche

Subjects
Medicine, Science
Abstract

BACKGROUND:Coactivation of agonist and antagonist lower limb muscles during gait stiffens joints and ensures stability. In patients with multiple sclerosis, coactivation of lower limb muscles might be a compensatory mechanism to cope with impairments of balance and gait. OBJECTIVE:The aim of this study was to assess coactivation of agonist and antagonist muscles at the knee and ankle joints during gait in patients with multiple sclerosis, and to evaluate the relationship between muscle coactivation and disability, gait performance, dynamic ankle strength measured during gait, and postural stability. METHODS:The magnitude and duration of coactivation of agonist-antagonist muscle pairs at the knee and ankle were determined for both lower limbs (more and less-affected) in 14 patients with multiple sclerosis and 11 healthy subjects walking at a spontaneous speed, using 3D-gait analysis. RESULTS:In the patient group, coactivation was increased in the knee muscles during single support (proximal strategy) and in the ankle muscles during double support (distal strategy). The magnitude of coactivation was highest in the patients with the slowest gait, the greatest motor impairment and the most instability. CONCLUSION:Increased muscle coactivation is likely a compensatory mechanism to limit the number of degrees of freedom during gait in patients with multiple sclerosis, particularly when postural stability is impaired.

Published
2016
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4. Deterministic placement of ultra-bright near-infrared color centers in arrays of silicon carbide micropillars

Author

Hans Jürgen von Bardeleben, Abdul Salam Al Atem, Faraz A. Inam, Stefania Castelletto, Sophie Hameau, Jean-Marie Bluet, Shin-ichiro Sato, Alberto Boretti, Ahmed Fahad Almutairi, Gérard Guillot, School of Engineering, RMIT University, Melbourne, Victoria 3001, Australia, Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon, Laboratoire Pierre Aigrain (LPA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Fabrication, Silicon, Infrared, General Physics and Astronomy, chemistry.chemical_element, 02 engineering and technology, vacancy, lcsh:Chemical technology, lcsh:Technology, 01 natural sciences, Full Research Paper, Ion, chemistry.chemical_compound, color centers, silicon carbide, Vacancy defect, 0103 physical sciences, Silicon carbide, Nanotechnology, lcsh:TP1-1185, General Materials Science, Electrical and Electronic Engineering, quantum sensing, [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, lcsh:Science, 010306 general physics, micropillars, lcsh:T, business.industry, Near-infrared spectroscopy, proton irradiation, 021001 nanoscience & nanotechnology, Fluorescence, lcsh:QC1-999, Nanoscience, chemistry, Optoelectronics, lcsh:Q, 0210 nano-technology, business, lcsh:Physics
Abstract

We report the enhancement of the optical emission between 850 and 1400 nm of an ensemble of silicon mono-vacancies (VSi), silicon and carbon divacancies (VCVSi), and nitrogen vacancies (NCVSi) in an n-type 4H-SiC array of micropillars. The micropillars have a length of ca. 4.5 μm and a diameter of ca. 740 nm, and were implanted with H+ ions to produce an ensemble of color centers at a depth of approximately 2 μm. The samples were in part annealed at different temperatures (750 and 900 °C) to selectively produce distinct color centers. For all these color centers we saw an enhancement of the photostable fluorescence emission of at least a factor of 6 using micro-photoluminescence systems. Using custom confocal microscopy setups, we characterized the emission of VSi measuring an enhancement by up to a factor of 20, and of NCVSi with an enhancement up to a factor of 7. The experimental results are supported by finite element method simulations. Our study provides the pathway for device design and fabrication with an integrated ultra-bright ensemble of VSi and NCVSi for in vivo imaging and sensing in the infrared.

Published
2019

5. Nitrogen vacancy center in cubic silicon carbide: A promising qubit in the 1.5μm spectral range for photonic quantum networks

Author

J. L. Cantin, B. Eble, Weibo Gao, Soroush Abbasi Zargaleh, Sophie Hameau, Florent Margaillan, and H. J. von Bardeleben

Subjects
Physics, Spin polarization, Phonon, Center (category theory), Spin–lattice relaxation, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Excited state, 0103 physical sciences, Atomic physics, 010306 general physics, 0210 nano-technology, Nitrogen-vacancy center, Ground state, Spin (physics)
Abstract

We have investigated the optical properties of the ${(\mathrm{NV})}^{\ensuremath{-}}$ center in 3C-SiC to determine the photoluminscence zero phonon line (ZPL) associated with the $^{3}\mathrm{E}\ensuremath{\rightarrow}^{3}\mathrm{A}_{2}$ intracenter transition. Combining electron paramagnetic resonance and photoluminescence spectroscopy, we show that the ${\mathrm{NV}}^{\ensuremath{-}}\phantom{\rule{0.28em}{0ex}}\mathrm{center}$ in 3C-SiC has a ZPL line at 1.468 $\ensuremath{\mu}\mathrm{m}$ in excellent agreement with theoretical predictions. The ZPL line can be observed up to $T=100$ K. The negatively charged NV center in 3C-SiC is the structural isomorphe of the NV center in diamond and has equally a spin $S=1$ ground state and a spin $S=1$ excited state, long spin lattice relaxation times and presents optically induced groudstate spin polarization. These properties make it already a strong competitor to the NV center in diamond, but as its optical domain is shifted in the near infrared at $1.5\phantom{\rule{0.16em}{0ex}}\ensuremath{\mu}\mathrm{m}$, the NV center in 3C-SiC is compatible with quantum photonic networks and silicon based microelectronics.

Published
2018

6. Electron paramagnetic resonance tagged High Resolution Excitation Spectroscopy of NV-Centers in 4H-SiC

Author

H. J. von Bardeleben, Weibo Gao, B. Eble, Uwe Gerstmann, Soroush Abbasi Zargaleh, J. L. Cantin, Sophie Hameau, Nanyang Technological University [Singapour], Institut des Nanosciences de Paris (INSP), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), School of Physical and Mathematical Sciences, The Photonics Institute, and Centre for Disruptive Photonic Technologies (CDPT)

Subjects
Photoluminescence, Absorption spectroscopy, Phonon, Science::Physics [DRNTU], 02 engineering and technology, 01 natural sciences, Atomic, Spectral line, law.invention, Molecular & Optical, law, 0103 physical sciences, fine and hyperfine structure, Emission spectrum, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, Electron paramagnetic resonance, Spectroscopy, defects, Physics, Condensed Matter & Materials Physics, 021001 nanoscience & nanotechnology, Photoexcitation, magneto-optical spectra, Defects, Quantum Information, Atomic physics, Fine & Hyperfine Structure, 0210 nano-technology
Abstract

We show that electron paramagnetic resonance (EPR) tagged high resolution photoexcitation spectroscopy is a powerful method for the correlation of zero phonon photoluminescence spectra with atomic point defects. Applied to the case of NV centers in $4H$-SiC it allows to associate the photoluminescence zero phonon lines (ZPL) at 1243, 1223, 1180, and 1176 nm with the (hk, kk, hh, kh) configurations of the ${\mathrm{NV}}^{\ensuremath{-}}$centers in this material. These results lead to a revision of a previous tentative assignment. Contrary to theoretical predictions, we find that the NV centers in $4H$-SiC show a negligible Franck-Condon shift as their ZPL absorption lines are resonant with the ZPL emission lines. The high subnanometer energy resolution of this technique allows us further to resolve additional fine-structure of the ZPL lines of the axial NV centers which show a doublet structure with a splitting of 0.8 nm. Our results confirm that NV centers in $4H$-SiC provide strong competitors for sensing and qubit application due to the shift of their optical transitions into the technology compatible near-infrared region and the superior material properties of SiC. Given that single center spin readout will be realized, they are suitable for scalable nanophotonic devices compatible with optical communication network.

Published
2018

7. Evidence for near-infrared photoluminescence of nitrogen vacancy centers in 4 H -SiC

Author

B. Eble, Sophie Hameau, S. A. Zargaleh, Laurent Legrand, Uwe Gerstmann, Eva Rauls, H. J. von Bardeleben, Jean-François Roch, Florent Margaillan, J. L. Cantin, Mathieu Bernard, François Treussart, Jean-Sébastien Lauret, Laboratoire Aimé Cotton (LAC), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-École normale supérieure - Cachan (ENS Cachan), Institut des Nanosciences de Paris (INSP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), University of Paderborn, École normale supérieure - Cachan (ENS Cachan)-Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Nanostructures et systèmes quantiques (INSP-E1), 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), Couches nanométriques : formation, interfaces, défauts (INSP-E5), Centre d'Investigation Clinique 1432 (Dijon) - Epidemiologie Clinique/Essais Cliniques (CIC-EC), Université de Bourgogne (UB)-Centre Hospitalier Universitaire de Dijon - Hôpital François Mitterrand (CHU Dijon)-Institut National de la Santé et de la Recherche Médicale (INSERM), Laboratoire Electronique, Informatique et Image [UMR6306] (Le2i), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Arts et Métiers (ENSAM), Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM)-Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement, RENARD (TGE Réseau National de RPE interdisciplinaire - 3443), Laboratoire de Chimie et de Biochimie Pharmacologiques et Toxicologiques (LCBPT - UMR 8601), Centre National de la Recherche Scientifique (CNRS)-Université Paris Descartes - Paris 5 (UPD5)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Descartes - Paris 5 (UPD5)-FR-CNRS 3443-Université Paris Descartes - Paris 5 (UPD5)-Centre National de la Recherche Scientifique (CNRS), AREVA, Groupe AREVA, RENARD (TGE Réseau National de RPE interdisciplinaire - 3443 ), Université Paris Descartes - Paris 5 (UPD5)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Descartes - Paris 5 (UPD5)-Centre National de la Recherche Scientifique (CNRS)-FR-CNRS 3443-Université Paris Descartes - Paris 5 (UPD5)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Aix Marseille Université (AMU)-Sorbonne Université (SU)-Université de Lille-Université de Strasbourg (UNISTRA), Laboratoire Aimé Cotton ( LAC ), École normale supérieure - Cachan ( ENS Cachan ) -Université Paris-Sud - Paris 11 ( UP11 ) -Centre National de la Recherche Scientifique ( CNRS ), Nanostructures et systèmes quantiques ( INSP-E1 ), Institut des Nanosciences de Paris ( INSP ), 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 ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ), Couches nanométriques : formation, interfaces, défauts ( INSP-E5 ), Centre d'Investigation Clinique 1432 (Dijon) - Epidemiologie Clinique/Essais Cliniques ( CIC-EC ), Université de Bourgogne ( UB ) -Centre Hospitalier Universitaire de Dijon - Hôpital François Mitterrand ( CHU Dijon ) -Institut National de la Santé et de la Recherche Médicale ( INSERM ), Laboratoire Electronique, Informatique et Image ( Le2i ), Université de Bourgogne ( UB ) -AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique ( CNRS ), RENARD ( TGE Réseau National de RPE interdisciplinaire ), FR-CNRS 3443, Centre National de la Recherche Scientifique (CNRS)-Université Paris Descartes - Paris 5 (UPD5)-FR-CNRS 3443-Laboratoire de Chimie et de Biochimie Pharmacologiques et Toxicologiques (LCBPT - UMR 8601), and Université Paris Descartes - Paris 5 (UPD5)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Descartes - Paris 5 (UPD5)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Photoluminescence, Phonon, [ PHYS.COND.CM-MS ] Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Diamond, 02 engineering and technology, engineering.material, 021001 nanoscience & nanotechnology, 7. Clean energy, 01 natural sciences, Molecular physics, law.invention, Photoexcitation, Condensed Matter::Materials Science, law, Vacancy defect, 0103 physical sciences, engineering, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Photoluminescence excitation, 010306 general physics, 0210 nano-technology, Electron paramagnetic resonance, Ground state
Abstract

International audience; We present evidence of near-infrared photoluminescence (PL) signature of nitrogen vacancy centers (NCVSi)− in silicon carbide (SiC). This center exhibits an S=1 ground state spin similar to the NV− center in diamond. We have performed photoluminescence excitation measurements at cryogenic temperature and demonstrated efficient photoexcitation of distinct photoluminescence from (NCVSi)− in 4H-SiC. Furthermore, by correlating the energies of measured zero phonon lines (ZPLs) with theoretical values derived from hybrid density functional theory each of the ZPLs has been associated to the respective occupation of hexagonal (h) and quasicubic (k) lattice sites in close analogy to neutral divacancy centers (VCVSi)0 in the same material. Finally, with the appropriate choice of excitation energy we demonstrated the selective excitation of (NCVSi)− PL with no contamination by (VCVSi)0 PL, thereby opening the way towards the optical detection of (NCVSi)− electron spin resonance.

Published
2016

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