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13 results on '"Laura Oudjedi"'

1. High-Sensitivity X-ray Phase Imaging System Based on a Hartmann Wavefront Sensor

Author

Ginevra Begani Provinciali, Martin Piponnier, Laura Oudjedi, Xavier Levecq, Fabrice Harms, Alessia Cedola, Ombeline de La Rochefoucauld, and Philippe Zeitoun

Subjects
phase imaging, Hartmann sensor, tomography, X-rays, Physics, QC1-999
Abstract

The Hartman wavefront sensor can be used for X-ray phase imaging with high angular resolution. The Hartmann sensor is able to retrieve both the phase and absorption from a single acquisition. The system calculates the shift in a series of apertures imaged with a detector with respect to their reference positions. In this article, the impact of the reference image on the final image quality is investigated using a laboratory setup. Deflection and absorption images of the same sample are compared using reference images acquired in air and in water. It can be easily coupled with tomographic setups to obtain 3D images of both phase and absorption. Tomographic images of a test sample are shown, where deflection images revealed details that were invisible in absorption. The findings reported in this paper can be used for the improvement of image reconstruction and for expanding the applications of X-ray phase imaging towards materials characterization and medical imaging.

Published
2021
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2. Highly efficient multicolor multifocus microscopy by optimal design of diffraction binary gratings

Author

Bassam Hajj, Laura Oudjedi, Jean-Bernard Fiche, Maxime Dahan, and Marcelo Nollmann

Subjects
Medicine, Science
Abstract

Abstract Multifocus microscopy (MFM) allows sensitive and fast three-dimensional imaging. It relies on the efficient design of diffraction phase gratings yielding homogeneous intensities in desired diffraction orders. Such performances are however guaranteed only for a specific wavelength. Here, we discuss a novel approach for designing binary phase gratings with dual color properties and improved diffraction efficiency for MFM. We simulate binary diffraction gratings with tunable phase shifts to explore its best diffraction performances. We report the design and fabrication of a binary array generator of 3 × 3 equal-intensity diffraction orders with 74% efficiency, 95% uniformity and dual color capability. The multicolor properties of this new design are highlighted by two-color MFM imaging. Finally, we discuss the basics of extending this approach to a variety of diffraction pattern designs.

Published
2017
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3. Bacterial partition complexes segregate within the volume of the nucleoid

Author

Antoine Le Gall, Diego I. Cattoni, Baptiste Guilhas, Céline Mathieu-Demazière, Laura Oudjedi, Jean-Bernard Fiche, Jérôme Rech, Sara Abrahamsson, Heath Murray, Jean-Yves Bouet, and Marcelo Nollmann

Subjects
Science
Abstract

In most bacteria and archaea, a broadly conserved mitotic-like apparatus assures the inheritance of duplicated genetic material before cell division. Here, the authors use super-resolution microscopies to dissect the activities required for proper DNA segregation through the nucleoid interior.

Published
2016
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4. Element differentiation with a Hartmann- based X-ray phase imaging system

Author

Ombeline de La Rochefoucauld, Ginevra Begani Provinciali, Alessia Cedola, Philip K. Cook, Francesca Di Lillo, Guillaume Dovillaire, Fabrice Harms, Mourad Idir, Xavier Levecq, Laura Oudjedi, Tan-Binh Phan, Martin Piponnier, Giuliana Tromba, and Philippe Zeitoun

Subjects
Mechanics of Materials, Mechanical Engineering, General Physics and Astronomy, General Materials Science
Published
2022
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5. Bacterial partition complexes segregate within the volume of the nucleoid

Author

Sara Abrahamsson, Baptiste Guilhas, Laura Oudjedi, Antoine Le Gall, Jean-Yves Bouet, Marcelo Nollmann, Diego I. Cattoni, Heath Murray, Jean-Bernard Fiche, Céline Mathieu-Demazière, and Jérôme Rech

Subjects
0301 basic medicine, DNA, Bacterial, animal structures, Cell division, Science, General Physics and Astronomy, Gene Expression, DNA Primase, General Biochemistry, Genetics and Molecular Biology, Article, 03 medical and health sciences, chemistry.chemical_compound, Bacterial Proteins, Chromosome Segregation, Escherichia coli, Nucleoid, Genetics, Multidisciplinary, biology, Circular bacterial chromosome, Escherichia coli Proteins, Volume (computing), Inheritance (genetic algorithm), General Chemistry, Chromosomes, Bacterial, biology.organism_classification, Partition (database), Cell Compartmentation, 030104 developmental biology, chemistry, Biophysics, DNA, Archaea, Bacillus subtilis, Protein Binding
Abstract

Precise and rapid DNA segregation is required for proper inheritance of genetic material. In most bacteria and archaea, this process is assured by a broadly conserved mitotic-like apparatus in which a NTPase (ParA) displaces the partition complex. Competing observations and models imply starkly different 3D localization patterns of the components of the partition machinery during segregation. Here we use super-resolution microscopies to localize in 3D each component of the segregation apparatus with respect to the bacterial chromosome. We show that Par proteins locate within the nucleoid volume and reveal that proper volumetric localization and segregation of partition complexes requires ATPase and DNA-binding activities of ParA. Finally, we find that the localization patterns of the different components of the partition system highly correlate with dense chromosomal regions. We propose a new mechanism in which the nucleoid provides a scaffold to guide the proper segregation of partition complexes., In most bacteria and archaea, a broadly conserved mitotic-like apparatus assures the inheritance of duplicated genetic material before cell division. Here, the authors use super-resolution microscopies to dissect the activities required for proper DNA segregation through the nucleoid interior.

Published
2016

6. Direct visualization of carbon nanotube degradation in primary cells by photothermal imaging

Author

Julie Russier, Brahim Lounis, Kostas Kostarelos, Cyrill Bussy, Laura Oudjedi, Laurent Cognet, Alberto Bianco, Maurizio Prato, Martin Piponnier, Russier, Julie, Oudjedi, Laura, Piponnier, Martin, Bussy, Cyrill, Prato, Maurizio, Kostarelos, Kosta, Lounis, Brahim, Bianco, Alberto, Cognet, Laurent, Immunologie et chimie thérapeutiques (ICT), Cancéropôle du Grand Est-Centre National de la Recherche Scientifique (CNRS), lp2n-04,lp2n-12, Laboratoire Photonique, Numérique et Nanosciences (LP2N), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS), ONERA - The French Aerospace Lab [Palaiseau], ONERA-Université Paris Saclay (COmUE), Université de Bordeaux (UB)-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS), Physiopathologie et Epidemiologie de l'Insuffisance Respiratoire, Université Paris Diderot - Paris 7 (UPD7)-Institut National de la Santé et de la Recherche Médicale (INSERM), University of Manchester [Manchester], Dipartimento di Scienze Farmaceutiche, Università degli studi di Trieste = University of Trieste, Université Sciences et Technologies - Bordeaux 1-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS), and University of Trieste

Subjects
Materials science, [PHYS.PHYS.PHYS-BIO-PH]Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], brain, Carbon nanotubes, microglia, Nanotechnology, 02 engineering and technology, Carbon nanotube, 010402 general chemistry, 01 natural sciences, biodegradation, law.invention, drug delivery systems, Interference (communication), National Graphene Institute, law, General Materials Science, Primary cell, ComputingMilieux_MISCELLANEOUS, [PHYS.PHYS.PHYS-BIO-PH] Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], carbon nanotubes, Photothermal imaging, ResearchInstitutes_Networks_Beacons/03/02, Photothermal therapy, Biodegradation, 021001 nanoscience & nanotechnology, Fluorescence, 0104 chemical sciences, ResearchInstitutes_Networks_Beacons/national_graphene_institute, Degradation (geology), Chimie/Chimie thérapeutique, Electron microscope, 0210 nano-technology, Advanced materials, photothermal imaging
Abstract

Assessment of biodegradability of carbon nanotubes (CNTs) is a critically important aspect that needs to be solved before their translation into new biomedical tools. CNT biodegradation has been shown both in vitro and in vivo, but we are limited by the number of analytical techniques that can be used to follow the entire process. Photothermal imaging (PhI) is an innovative technique that enables the quantitative detection of nanometer-sized absorptive objects. In this study, we demonstrate that PhI allows the observation of the degradation process of functionalized multi-walled carbon nanotubes (MWCNTs) following their internalization by primary glial cells. The absence of interference from the biological matrix components, together with the possibility to combine PhI with other detection techniques (e.g. fluorescence, light or electron microscopy) validate the potential of this method to follow the fate and behavior of carbon nanostructures in a biological environment. journal article 2017 Apr 06 imported

Published
2017
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7. Astigmatic multifocus microscopy enables deep 3D super-resolved imaging

Author

Laurent Mazenq, Aline Cerf, Marcelo Nollmann, Pierre-François Calmon, Aurélie Lecestre, Jean-Bernard Fiche, Sara Abrahamsson, Laura Oudjedi, Centre de Biochimie Structurale [Montpellier] (CBS), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de la Santé et de la Recherche Médicale (INSERM), Rockefeller University [New York], Service Techniques et Équipements Appliqués à la Microélectronique (LAAS-TEAM), Laboratoire d'analyse et d'architecture des systèmes (LAAS), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées, Équipe Ingénierie pour les sciences du vivant (LAAS-ELIA), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse Capitole (UT Capitole), and Université de Toulouse (UT)

Subjects
0301 basic medicine, Diffraction, [PHYS]Physics [physics], Materials science, business.industry, Grating, Diffraction efficiency, 01 natural sciences, Atomic and Molecular Physics, and Optics, Article, 010309 optics, 03 medical and health sciences, 030104 developmental biology, Optics, Multifocal plane microscopy, 0103 physical sciences, Microscopy, Depth of field, Adaptive optics, business, Diffraction grating, Biotechnology
Abstract

International audience; We have developed a 3D super-resolution microscopy method that enables deep imaging in cells. This technique relies on the effective combination of multifocus microscopy and astigmatic 3D single-molecule localization microscopy. We describe the optical system and the fabrication process of its key element, the multifocus grating. Then, two strategies for localizing emitters with our imaging method are presented and compared with a previously described deep 3D localization algorithm. Finally, we demonstrate the performance of the method by imaging the nuclear envelope of eukaryotic cells reaching a depth of field of ~4µm.

Published
2016
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8. Multifocus microscopy with precise color multi-phase diffractive optics applied in functional neuronal imaging

Author

Joan Pulupa, Lei Chen, Sara Abrahamsson, Bassam Hajj, Liya Yu, Mohamed El Beheiry, Xavier Darzacq, Marcelo Davanco, Mustafa Mir, Laura Oudjedi, Jan Wisniewski, Jean-Bernard Fiche, Marcelo Nollmann, Cornelia I. Bargmann, J. Alexander Liddle, Carl Wu, Rob Ilic, Xin Jin, Christine E. Cho, Maxime Dahan, Timothée Lionnet, Brian Mehl, Rockefeller University [New York], National Institute of Standards and Technology [Gaithersburg] (NIST), Janelia Farm Research Campus, Howard Hughes Medical Institute (HHMI), Centre de Biochimie Structurale [Montpellier] (CBS), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de la Santé et de la Recherche Médicale (INSERM), Physico-Chimie-Curie (PCC), Centre National de la Recherche Scientifique (CNRS)-Institut Curie [Paris]-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie du CNRS (INC), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), HAL UPMC, Gestionnaire, Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut Curie [Paris]-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0301 basic medicine, Photon, Materials science, Image quality, [SDV.IB.IMA]Life Sciences [q-bio]/Bioengineering/Imaging, (110.4190) Multiple imaging, (180.2520) Fluorescence microscopy, (260.5430) Polarization, Bioengineering, Optical Physics, Grating, 01 natural sciences, Three-dimensional microscopy, Article, 010309 optics, 03 medical and health sciences, Biological specimen, Optics, Affordable and Clean Energy, Polarization, 0103 physical sciences, Microscopy, Diffractive optics, Multiple imaging, Fluorescence microscopy, business.industry, Ranging, Materials Engineering, (050.1970) Diffractive optics, Frame rate, Atomic and Molecular Physics, and Optics, 030104 developmental biology, Nanolithography, [SDV.IB.IMA] Life Sciences [q-bio]/Bioengineering/Imaging, (180.6900) Three-dimensional microscopy, Generic health relevance, business, Biotechnology
Abstract

International audience; Multifocus microscopy (MFM) allows high-resolution instantaneous three-dimensional (3D) imaging and has been applied to study biological specimens ranging from single molecules inside cells nuclei to entire embryos. We here describe pattern designs and nanofabrication methods for diffractive optics that optimize the light-efficiency of the central optical component of MFM: the diffractive multifocus grating (MFG). We also implement a " precise color " MFM layout with MFGs tailored to individual fluorophores in separate optical arms. The reported advancements enable faster and brighter volumetric time-lapse imaging of biological samples. In live microscopy applications, photon budget is a critical parameter and light-efficiency must be optimized to obtain the fastest possible frame rate while minimizing photodamage. We provide comprehensive descriptions and code for designing diffractive optical devices, and a detailed methods description for nanofabrication of devices. Theoretical efficiencies of reported designs is ≈90% and we have obtained efficiencies of > 80% in MFGs of our own manufacture. We demonstrate the performance of a multi-phase MFG in 3D functional neuronal imaging in living C. elegans.

Published
2015
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9. Optical detection of individual ultra-short carbon nanotubes enables their length characterization down to 10 nm

Author

Zhenghong Gao, Laura Oudjedi, Romain Faes, Fabien Moroté, Christèle Jaillet, Philippe Poulin, Brahim Lounis, and Laurent Cognet

Subjects
Article
Abstract

Ultrashort single-walled carbon nanotubes, i.e. with length below ~30 nm, display length-dependent physical, chemical and biological properties that are attractive for the development of novel nanodevices and nanomaterials. Whether fundamental or applicative, such developments require that ultrashort nanotube lengths can be routinely and reliably characterized with high statistical data for high-quality sample production. However, no methods currently fulfill these requirements. Here, we demonstrate that photothermal microscopy achieves fast and reliable optical single nanotube analysis down to ~10 nm lengths. Compared to atomic force microscopy, this method provides ultrashort nanotubes length distribution with high statistics, and neither requires specific sample preparation nor tip-dependent image analysis.

Published
2015

10. Preparation, Analysis and Optical Detection of Individual Ultra-short Single-Walled Carbon Nanotubes (<30 nm)

Author

Zhenghong Gao, Laura Oudjedi, Romain Faes, Fabien Morotè, Christèle Jaillet, Philippe Poulin, Brahim Lounis, Laurent Cognet, lp2n-01,lp2n-12, Laboratoire Photonique, Numérique et Nanosciences (LP2N), Université Sciences et Technologies - Bordeaux 1-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ondes et Matière d'Aquitaine (LOMA), Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS), Centre de recherches Paul Pascal (CRPP), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Gao, Zhenghong

Subjects
[CHIM.MATE] Chemical Sciences/Material chemistry, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [CHIM.MATE]Chemical Sciences/Material chemistry, [PHYS.COND.CM-MS] Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2014

11. A Metrological investigation of the (6, 5) carbon nanotube absorption cross section

Author

Antoine G. Godin, Laurent Cognet, Laura Oudjedi, A. Nicholas G. Parra-Vasquez, Brahim Lounis, lp2n-01,lp2n-12, Laboratoire Photonique, Numérique et Nanosciences (LP2N), Université Sciences et Technologies - Bordeaux 1-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS), and Université Sciences et Technologies - Bordeaux 1-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nanotube, Exciton, FOS: Physical sciences, 02 engineering and technology, Carbon nanotube, 01 natural sciences, Molecular physics, law.invention, Condensed Matter::Materials Science, law, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, Atom, Microscopy, General Materials Science, Physical and Theoretical Chemistry, Diffusion (business), 010306 general physics, Absorption (electromagnetic radiation), Physics, Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics, Absorption cross section, Materials Science (cond-mat.mtrl-sci), 021001 nanoscience & nanotechnology, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0210 nano-technology
Abstract

International audience; Using single-nanotube absorption microscopy, we measured the absorption cross section of (6,5) carbon nanotubes at their second-order optical transition. We obtained a value of 3.2 × 10-17 cm2/C atom with a precision of 15% and an accuracy below 20%. This constitutes the first metrological investigation of the absorption cross section of chirality-identified nanotubes. Correlative absorption-luminescence microscopies performed on long nanotubes reveal a direct manifestation of exciton diffusion in the nanotube.

Published
2013
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12. Mechanism of electrolyte-induced brightening in single-wall carbon nanotubes

Author

Jared Crochet, Laurent Cognet, Sergei Tretiak, Juan G. Duque, Brahim Lounis, Laura Oudjedi, Stephen K. Doorn, Physical Chemistry and Applied Spectroscopy, Los Alamos National Laboratory (LANL), lp2n-01,lp2n-12, Laboratoire Photonique, Numérique et Nanosciences (LP2N), Université Sciences et Technologies - Bordeaux 1-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS), and Center for Integrated Nanotechnologies

Subjects
Nanotube, Photoluminescence, Luminescence, [PHYS.PHYS.PHYS-BIO-PH]Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], Exciton, Diffusion, FOS: Physical sciences, 02 engineering and technology, Electrolyte, Carbon nanotube, 010402 general chemistry, Photochemistry, 01 natural sciences, Biochemistry, Catalysis, law.invention, Electrolytes, Colloid and Surface Chemistry, Pulmonary surfactant, law, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Condensed Matter - Materials Science, Quenching (fluorescence), Condensed Matter - Mesoscale and Nanoscale Physics, Chemistry, Nanotubes, Carbon, Materials Science (cond-mat.mtrl-sci), Sodium Dodecyl Sulfate, General Chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0210 nano-technology
Abstract

International audience; While addition of electrolyte to sodium dodecyl sulfate suspensions of single-wall carbon nanotubes has been demonstrated to result in significant brightening of the nanotube photoluminescence (PL), the brightening mechanism has remained unresolved. Here, we probe this mechanism using time-resolved PL decay measurements. We find that PL decay times increase by a factor of 2 on addition of CsCl as the electrolyte. Such an increase directly parallels an observed near-doubling of PL intensity, indicating the brightening results primarily from changes in nonradiative decay rates associated with exciton diffusion to quenching sites. Our findings indicate that a reduced number of these sites results from electrolyte-induced reorientation of the surfactant surface structure that partially removes pockets of water from the tube surface where excitons can dissociate, and thus underscores the contribution of interfacial water in exciton recombination processes.

Published
2013
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13. Nanoscale Thermotropic Phase Transitions Enhance Photothermal Microscopy Signals

Author

Brahim Lounis, Laurent Cognet, A. Nicholas G. Parra-Vasquez, Laura Oudjedi, Laboratoire Photonique, Numérique et Nanosciences (LP2N), Université Sciences et Technologies - Bordeaux 1-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS), lp2n-01,lp2n-12, and Université Sciences et Technologies - Bordeaux 1-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut d'Optique Graduate School (IOGS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Phase transition, Materials science, single molecule detection, FOS: Physical sciences, 02 engineering and technology, 01 natural sciences, Thermotropic crystal, liquid crystals, Liquid crystal, 0103 physical sciences, Microscopy, Water environment, General Materials Science, Physical and Theoretical Chemistry, 010306 general physics, Condensed Matter - Materials Science, business.industry, thermotropic phase transition, Materials Science (cond-mat.mtrl-sci), Photothermal therapy, 021001 nanoscience & nanotechnology, Photothermal microscopy, Colloidal gold, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], Optoelectronics, nanoparticles, sense organs, 0210 nano-technology, business, Refractive index, Physics - Optics, Optics (physics.optics)
Abstract

International audience; The photothermal heterodyne imaging technique enabled studies of individual weakly absorbing nano-objects in various environments. It uses a photo-induced change in the refractive index of the environment. Taking advantage of the dramatic index of refraction change occurring around a thermotropic liquid crystalline phase transition, we demonstrate a 40-fold signal-to-noise ratio enhancement for gold nanoparticles imaged in 4-Cyano-4'-pentylbiphenyl (5CB) liquid crystals over those in a water environment. We studied the photothermal signal as a function of probe laser polarization, heating power, and sample temperature quantifying the optimal enhancement. This study established photothermal microscopy as a valuable technique for inducing and/or detecting local phase transitions at the nanometer scales.

Published
2012
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