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Rosławska A, Kaiser K, Romeo M, Devaux E, Scheurer F, Berciaud S, Neuman T, Schull G. Submolecular-scale control of phototautomerization. Nat Nanotechnol 2024:10.1038/s41565-024-01622-4. [PMID: 38413791 DOI: 10.1038/s41565-024-01622-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 01/29/2024] [Indexed: 02/29/2024]
Abstract
Optically activated reactions initiate biological processes such as photosynthesis or vision, but can also control polymerization, catalysis or energy conversion. Methods relying on the manipulation of light at macroscopic and mesoscopic scales are used to control on-surface photochemistry, but do not offer atomic-scale control. Here we take advantage of the confinement of the electromagnetic field at the apex of a scanning tunnelling microscope tip to drive the phototautomerization of a free-base phthalocyanine with submolecular precision. We can control the reaction rate and the relative tautomer population through a change in the laser excitation wavelength or through the tip position. Atomically resolved tip-enhanced photoluminescence spectroscopy and hyperspectral mapping unravel an excited-state mediated process, which is quantitatively supported by a comprehensive theoretical model combining ab initio calculations with a parametric open-quantum-system approach. Our experimental strategy may allow insights in other photochemical reactions and proof useful to control complex on-surface reactions.
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Affiliation(s)
- Anna Rosławska
- Université de Strasbourg, CNRS, IPCMS, Strasbourg, France.
- Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
| | - Katharina Kaiser
- Université de Strasbourg, CNRS, IPCMS, Strasbourg, France
- 4th Physical Institute - Solids and Nanostructures, Georg-August-Universität Göttingen, Göttingen, Germany
| | | | - Eloïse Devaux
- Université de Strasbourg, CNRS, ISIS, Strasbourg, France
| | | | | | - Tomáš Neuman
- Institut des Sciences Moléculaires d'Orsay (ISMO), UMR 8214, CNRS, Université Paris-Saclay, Orsay, France.
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic.
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2
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López LEP, Rosławska A, Scheurer F, Berciaud S, Schull G. Tip-induced excitonic luminescence nanoscopy of an atomically resolved van der Waals heterostructure. Nat Mater 2023; 22:482-488. [PMID: 36928383 DOI: 10.1038/s41563-023-01494-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 01/30/2023] [Indexed: 06/18/2023]
Abstract
The electronic and optical properties of van der Waals heterostructures are strongly influenced by the structuration and homogeneity of their nano- and atomic-scale environments. Unravelling this intimate structure-property relationship is a key challenge that requires methods capable of addressing the light-matter interactions in van der Waals materials with ultimate spatial resolution. Here we use a low-temperature scanning tunnelling microscope to probe-with atomic-scale resolution-the excitonic luminescence of a van der Waals heterostructure, made of a transition metal dichalcogenide monolayer stacked onto a few-layer graphene flake supported by a Au(111) substrate. Sharp emission lines arising from neutral, charged and localized excitons are reported. Their intensities and emission energies vary as a function of the nanoscale topography of the van der Waals heterostructure, explaining the variability of the emission properties observed with diffraction-limited approaches. Our work paves the way towards understanding and controlling optoelectronic phenomena in moiré superlattices with atomic-scale resolution.
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Affiliation(s)
- Luis E Parra López
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, Strasbourg, France
| | - Anna Rosławska
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, Strasbourg, France
| | - Fabrice Scheurer
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, Strasbourg, France
| | - Stéphane Berciaud
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, Strasbourg, France.
| | - Guillaume Schull
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, Strasbourg, France.
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3
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Peña Román RJ, Bretel R, Pommier D, Parra López LE, Lorchat E, Boer-Duchemin E, Dujardin G, Borisov AG, Zagonel LF, Schull G, Berciaud S, Le Moal E. Tip-Induced and Electrical Control of the Photoluminescence Yield of Monolayer WS 2. Nano Lett 2022; 22:9244-9251. [PMID: 36458911 DOI: 10.1021/acs.nanolett.2c02142] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The photoluminescence (PL) of monolayer tungsten disulfide (WS2) is locally and electrically controlled using the nonplasmonic tip and tunneling current of a scanning tunneling microscope (STM). The spatial and spectral distribution of the emitted light is determined using an optical microscope. When the STM tip is engaged, short-range PL quenching due to near-field electromagnetic effects is present, independent of the sign and value of the bias voltage applied to the tip-sample tunneling junction. In addition, a bias-voltage-dependent long-range PL quenching is measured when the sample is positively biased. We explain these observations by considering the native n-doping of monolayer WS2 and the charge carrier density gradients induced by electron tunneling in micrometer-scale areas around the tip position. The combination of wide-field PL microscopy and charge carrier injection using an STM opens up new ways to explore the interplay between excitons and charge carriers in two-dimensional semiconductors.
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Affiliation(s)
- Ricardo Javier Peña Román
- Institute of Physics "Gleb Wataghin", Department of Applied Physics, State University of Campinas-UNICAMP, 13083-859 Campinas, Brazil
| | - Rémi Bretel
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - Delphine Pommier
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - Luis Enrique Parra López
- Institut de Physique et de Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Etienne Lorchat
- Physics & Informatics (PHI) Laboratories, NTT Research, Inc., Sunnyvale, California 94085, United States
| | - Elizabeth Boer-Duchemin
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - Gérald Dujardin
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - Andrei G Borisov
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, CNRS, 91405, Orsay, France
| | - Luiz Fernando Zagonel
- Institute of Physics "Gleb Wataghin", Department of Applied Physics, State University of Campinas-UNICAMP, 13083-859 Campinas, Brazil
| | - Guillaume Schull
- Institut de Physique et de Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Stéphane Berciaud
- Institut de Physique et de Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Eric Le Moal
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, CNRS, 91405, Orsay, France
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4
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Zhang X, Makles K, Colombier L, Metten D, Majjad H, Verlot P, Berciaud S. Dynamically-enhanced strain in atomically thin resonators. Nat Commun 2020; 11:5526. [PMID: 33139724 PMCID: PMC7608634 DOI: 10.1038/s41467-020-19261-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 10/01/2020] [Indexed: 11/13/2022] Open
Abstract
Graphene and related two-dimensional (2D) materials associate remarkable mechanical, electronic, optical and phononic properties. As such, 2D materials are promising for hybrid systems that couple their elementary excitations (excitons, phonons) to their macroscopic mechanical modes. These built-in systems may yield enhanced strain-mediated coupling compared to bulkier architectures, e.g., comprising a single quantum emitter coupled to a nano-mechanical resonator. Here, using micro-Raman spectroscopy on pristine monolayer graphene drums, we demonstrate that the macroscopic flexural vibrations of graphene induce dynamical optical phonon softening. This softening is an unambiguous fingerprint of dynamically-induced tensile strain that reaches values up to ≈4 × 10−4 under strong non-linear driving. Such non-linearly enhanced strain exceeds the values predicted for harmonic vibrations with the same root mean square (RMS) amplitude by more than one order of magnitude. Our work holds promise for dynamical strain engineering and dynamical strain-mediated control of light-matter interactions in 2D materials and related heterostructures. Here, the authors use Raman spectroscopy on circular graphene drums to demonstrate dynamical softening of optical phonons induced by the macroscopic flexural motion of graphene, and find evidence that the strain in graphene is enhanced under non-linear driving.
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Affiliation(s)
- Xin Zhang
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000, Strasbourg, France.
| | - Kevin Makles
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000, Strasbourg, France
| | - Léo Colombier
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000, Strasbourg, France
| | - Dominik Metten
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000, Strasbourg, France
| | - Hicham Majjad
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000, Strasbourg, France
| | - Pierre Verlot
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, United Kingdom.,Institut Universitaire de France, 1 rue Descartes, 05 75231, Paris Cedex, France
| | - Stéphane Berciaud
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000, Strasbourg, France. .,Institut Universitaire de France, 1 rue Descartes, 05 75231, Paris Cedex, France.
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5
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Noumbé UN, Gréboval C, Livache C, Chu A, Majjad H, Parra López LE, Mouafo LDN, Doudin B, Berciaud S, Chaste J, Ouerghi A, Lhuillier E, Dayen JF. Reconfigurable 2D/0D p-n Graphene/HgTe Nanocrystal Heterostructure for Infrared Detection. ACS Nano 2020; 14:4567-4576. [PMID: 32223229 DOI: 10.1021/acsnano.0c00103] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Nanocrystals are promising building blocks for the development of low-cost infrared optoelectronics. Gating a nanocrystal film in a phototransistor geometry is commonly proposed as a strategy to tune the signal-to-noise ratio by carefully controlling the carrier density within the semiconductor. However, the performance improvement has so far been quite marginal. With metallic electrodes, the gate dependence of the photocurrent follows the gate-induced change of the dark current. Graphene presents key advantages: (i) infrared transparency that allows back-side illumination, (ii) vertical electric field transparency, and (iii) carrier selectivity under gate bias. Here, we investigate a configuration of 2D/0D infrared photodetectors taking advantage of a high capacitance ionic glass gate, large-scale graphene electrodes, and a HgTe nanocrystals layer of high carrier mobility. The introduction of graphene electrodes combined with ionic glass enables one to reconfigure selectively the HgTe nanocrystals and the graphene electrodes between electron-doped (n) and hole-doped (p) states. We unveil that this functionality enables the design a 2D/0D p-n junction that expands throughout the device, with a built-in electric field that assists charge dissociation. We demonstrate that, in this specific configuration, the signal-to-noise ratio for infrared photodetection can be enhanced by 2 orders of magnitude, and that photovoltaic operation can be achieved. The detectivity now reaches 109 Jones, whereas the device only absorbs 8% of the incident light. Additionally, the time response of the device is fast (<10 μs), which strongly contrasts with the slow response commonly observed for 2D/0D mixed-dimensional heterostructures, where larger photoconduction gains come at the cost of slower response.
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Affiliation(s)
- Ulrich Nguétchuissi Noumbé
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504, 23 rue du Loess, Strasbourg 67034, France
| | - Charlie Gréboval
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, Paris F-75005, France
| | - Clément Livache
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, Paris F-75005, France
| | - Audrey Chu
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, Paris F-75005, France
| | - Hicham Majjad
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504, 23 rue du Loess, Strasbourg 67034, France
| | - Luis E Parra López
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504, 23 rue du Loess, Strasbourg 67034, France
| | - Louis Donald Notemgnou Mouafo
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504, 23 rue du Loess, Strasbourg 67034, France
| | - Bernard Doudin
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504, 23 rue du Loess, Strasbourg 67034, France
| | - Stéphane Berciaud
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504, 23 rue du Loess, Strasbourg 67034, France
- Institut Universitaire de France, 1 rue Descartes, Paris 75231 Cedex 05, France
| | - Julien Chaste
- Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Saclay, C2N, Palaiseau 2110, France
| | - Abdelkarim Ouerghi
- Centre de Nanosciences et de Nanotechnologies, CNRS, Université Paris-Saclay, C2N, Palaiseau 2110, France
| | - Emmanuel Lhuillier
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, Paris F-75005, France
| | - Jean-Francois Dayen
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504, 23 rue du Loess, Strasbourg 67034, France
- Institut Universitaire de France, 1 rue Descartes, Paris 75231 Cedex 05, France
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6
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Lorchat E, López LEP, Robert C, Lagarde D, Froehlicher G, Taniguchi T, Watanabe K, Marie X, Berciaud S. Filtering the photoluminescence spectra of atomically thin semiconductors with graphene. Nat Nanotechnol 2020; 15:283-288. [PMID: 32152557 DOI: 10.1038/s41565-020-0644-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 01/20/2020] [Indexed: 06/10/2023]
Abstract
Atomically thin semiconductors made from transition metal dichalcogenides (TMDs) are model systems for investigations of strong light-matter interactions and applications in nanophotonics, optoelectronics and valleytronics. However, the photoluminescence spectra of TMD monolayers display a large number of features that are particularly challenging to decipher. On a practical level, monochromatic TMD-based emitters would be beneficial for low-dimensional devices, but this challenge is yet to be resolved. Here, we show that graphene, directly stacked onto TMD monolayers, enables single and narrow-line photoluminescence arising solely from TMD neutral excitons. This filtering effect stems from complete neutralization of the TMD by graphene, combined with selective non-radiative transfer of long-lived excitonic species to graphene. Our approach is applied to four tungsten- and molybdenum-based TMDs and establishes TMD/graphene heterostructures as a unique set of optoelectronic building blocks that are suitable for electroluminescent systems emitting visible and near-infrared photons at near THz rate with linewidths approaching the homogeneous limit.
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Affiliation(s)
- Etienne Lorchat
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Strasbourg, France
| | - Luis E Parra López
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Strasbourg, France
| | - Cédric Robert
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, Toulouse, France
| | | | - Guillaume Froehlicher
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Strasbourg, France
| | | | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba, Ibaraki, Japan
| | - Xavier Marie
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, Toulouse, France
- Institut Universitaire de France, Paris, France
| | - Stéphane Berciaud
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Strasbourg, France.
- Institut Universitaire de France, Paris, France.
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7
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Doppagne B, Neuman T, Soria-Martinez R, López LEP, Bulou H, Romeo M, Berciaud S, Scheurer F, Aizpurua J, Schull G. Single-molecule tautomerization tracking through space- and time-resolved fluorescence spectroscopy. Nat Nanotechnol 2020; 15:207-211. [PMID: 31959932 DOI: 10.1038/s41565-019-0620-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 12/09/2019] [Indexed: 05/21/2023]
Abstract
Tautomerization, the interconversion between two constitutional molecular isomers, is ubiquitous in nature1, plays a major role in chemistry2 and is perceived as an ideal switch function for emerging molecular-scale devices3. Within free-base porphyrin4, porphycene5 or phthalocyanine6, this process involves the concerted or sequential hopping of the two inner hydrogen atoms between equivalent nitrogen sites of the molecular cavity. Electronic and vibronic changes6 that result from this NH tautomerization, as well as details of the switching mechanism, were extensively studied with optical spectroscopies, even with single-molecule sensitivity7. The influence of atomic-scale variations of the molecular environment and submolecular spatial resolution of the tautomerization could only be investigated using scanning probe microscopes3,8-11, at the expense of detailed information provided by optical spectroscopies. Here, we combine these two approaches, scanning tunnelling microscopy (STM) and fluorescence spectroscopy12-15, to study the tautomerization within individual free-base phthalocyanine (H2Pc) molecules deposited on a NaCl-covered Ag(111) single-crystal surface. STM-induced fluorescence (STM-F) spectra exhibit duplicate features that we assign to the emission of the two molecular tautomers. We support this interpretation by comparing hyper-resolved fluorescence maps15-18(HRFMs) of the different spectral contributions with simulations that account for the interaction between molecular excitons and picocavity plasmons19. We identify the orientation of the molecular optical dipoles, determine the vibronic fingerprint of the tautomers and probe the influence of minute changes in their atomic-scale environment. Time-correlated fluorescence measurements allow us to monitor the tautomerization events and to associate the proton dynamics to a switching two-level system. Finally, optical spectra acquired with the tip located at a nanometre-scale distance from the molecule show that the tautomerization reaction occurs even when the tunnelling current does not pass through the molecule. Together with other observations, this remote excitation indicates that the excited state of the molecule is involved in the tautomerization reaction path.
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Affiliation(s)
| | - Tomáš Neuman
- Center for Materials Physics (CSIC-UPV/EHU) and DIPC, Donostia-San Sebastián, Spain
| | | | | | - Hervé Bulou
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, Strasbourg, France
| | | | | | - Fabrice Scheurer
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, Strasbourg, France
| | - Javier Aizpurua
- Center for Materials Physics (CSIC-UPV/EHU) and DIPC, Donostia-San Sebastián, Spain
| | - Guillaume Schull
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, Strasbourg, France.
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8
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Pommier D, Bretel R, López LEP, Fabre F, Mayne A, Boer-Duchemin E, Dujardin G, Schull G, Berciaud S, Le Moal E. Scanning Tunneling Microscope-Induced Excitonic Luminescence of a Two-Dimensional Semiconductor. Phys Rev Lett 2019; 123:027402. [PMID: 31386496 DOI: 10.1103/physrevlett.123.027402] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Indexed: 05/24/2023]
Abstract
The long sought-after goal of locally and spectroscopically probing the excitons of two-dimensional (2D) semiconductors is attained using a scanning tunneling microscope (STM). Excitonic luminescence from monolayer molybdenum diselenide (MoSe_{2}) on a transparent conducting substrate is electrically excited in the tunnel junction of an STM under ambient conditions. By comparing the results with photoluminescence measurements, the emission mechanism is identified as the radiative recombination of bright A excitons. STM-induced luminescence is observed at bias voltages as low as those that correspond to the energy of the optical band gap of MoSe_{2}. The proposed excitation mechanism is resonance energy transfer from the tunneling current to the excitons in the semiconductor, i.e., through virtual photon coupling. Additional mechanisms (e.g., charge injection) may come into play at bias voltages that are higher than the electronic band gap. Photon emission quantum efficiencies of up to 10^{-7} photons per electron are obtained, despite the lack of any participating plasmons. Our results demonstrate a new technique for investigating the excitonic and optoelectronic properties of 2D semiconductors and their heterostructures at the nanometer scale.
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Affiliation(s)
- Delphine Pommier
- Institut des Sciences Moléculaires d'Orsay, CNRS, Université Paris Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - Rémi Bretel
- Institut des Sciences Moléculaires d'Orsay, CNRS, Université Paris Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - Luis E Parra López
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Florentin Fabre
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Andrew Mayne
- Institut des Sciences Moléculaires d'Orsay, CNRS, Université Paris Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - Elizabeth Boer-Duchemin
- Institut des Sciences Moléculaires d'Orsay, CNRS, Université Paris Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - Gérald Dujardin
- Institut des Sciences Moléculaires d'Orsay, CNRS, Université Paris Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - Guillaume Schull
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Stéphane Berciaud
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Eric Le Moal
- Institut des Sciences Moléculaires d'Orsay, CNRS, Université Paris Sud, Université Paris-Saclay, F-91405 Orsay, France
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9
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Miranda HPC, Reichardt S, Froehlicher G, Molina-Sánchez A, Berciaud S, Wirtz L. Quantum Interference Effects in Resonant Raman Spectroscopy of Single- and Triple-Layer MoTe 2 from First-Principles. Nano Lett 2017; 17:2381-2388. [PMID: 28199122 DOI: 10.1021/acs.nanolett.6b05345] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present a combined experimental and theoretical study of resonant Raman spectroscopy in single- and triple-layer MoTe2. Raman intensities are computed entirely from first-principles by calculating finite differences of the dielectric susceptibility. In our analysis, we investigate the role of quantum interference effects and the electron-phonon coupling. With this method, we explain the experimentally observed intensity inversion of the A1' vibrational modes in triple-layer MoTe2 with increasing laser photon energy. Finally, we show that a quantitative comparison with experimental data requires the proper inclusion of excitonic effects.
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Affiliation(s)
- Henrique P C Miranda
- Physics and Materials Science Research Unit, University of Luxembourg , 162a avenue de la Faïencerie, L-1511 Luxembourg, Luxembourg , EU
| | - Sven Reichardt
- Physics and Materials Science Research Unit, University of Luxembourg , 162a avenue de la Faïencerie, L-1511 Luxembourg, Luxembourg , EU
- JARA-FIT and 2nd Institute of Physics , Otto-Blumenthal-Straße, 52074 Aachen, Germany , EU
| | - Guillaume Froehlicher
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Université de Strasbourg, CNRS , UMR 7504, F-67000 Strasbourg, France , EU
| | - Alejandro Molina-Sánchez
- Physics and Materials Science Research Unit, University of Luxembourg , 162a avenue de la Faïencerie, L-1511 Luxembourg, Luxembourg , EU
| | - Stéphane Berciaud
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Université de Strasbourg, CNRS , UMR 7504, F-67000 Strasbourg, France , EU
| | - Ludger Wirtz
- Physics and Materials Science Research Unit, University of Luxembourg , 162a avenue de la Faïencerie, L-1511 Luxembourg, Luxembourg , EU
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Doppagne B, Chong MC, Lorchat E, Berciaud S, Romeo M, Bulou H, Boeglin A, Scheurer F, Schull G. Vibronic Spectroscopy with Submolecular Resolution from STM-Induced Electroluminescence. Phys Rev Lett 2017; 118:127401. [PMID: 28388196 DOI: 10.1103/physrevlett.118.127401] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Indexed: 05/12/2023]
Abstract
A scanning tunneling microscope is used to generate the electroluminescence of phthalocyanine molecules deposited on NaCl/Ag(111). Photon spectra reveal an intense emission line at ≈1.9 eV that corresponds to the fluorescence of the molecules, and a series of weaker redshifted lines. Based on a comparison with Raman spectra acquired on macroscopic molecular crystals, these spectroscopic features can be associated with the vibrational modes of the molecules and provide a detailed chemical fingerprint of the probed species. Maps of the vibronic features reveal submolecularly resolved structures whose patterns are related to the symmetry of the probed vibrational modes.
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Affiliation(s)
- Benjamin Doppagne
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Michael C Chong
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Etienne Lorchat
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Stéphane Berciaud
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Michelangelo Romeo
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Hervé Bulou
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Alex Boeglin
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Fabrice Scheurer
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Guillaume Schull
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
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Godel F, Mouafo LDN, Froehlicher G, Doudin B, Berciaud S, Henry Y, Dayen JF, Halley D. Conductance Oscillations in a Graphene/Nanocluster Hybrid Material: Toward Large-Area Single-Electron Devices. Adv Mater 2017; 29:1604837. [PMID: 27869338 DOI: 10.1002/adma.201604837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 10/05/2016] [Indexed: 06/06/2023]
Abstract
Large assemblies of self-organized aluminum nanoclusters embedded in an oxide layer are formed on graphene templates and used to build tunnel-junction devices. Unexpectedly, single-electron-transport behavior with well-defined Coulomb oscillations is observed for a record junction area of up to 100 µm2 containing millions of metal islands. Such graphene-metal nanocluster hybrid materials offer new prospects for single-electron electronics.
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Affiliation(s)
- Florian Godel
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034, Strasbourg Cedex 2, France
| | - Louis Donald Notemgnou Mouafo
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034, Strasbourg Cedex 2, France
| | - Guillaume Froehlicher
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034, Strasbourg Cedex 2, France
| | - Bernard Doudin
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034, Strasbourg Cedex 2, France
| | - Stéphane Berciaud
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034, Strasbourg Cedex 2, France
| | - Yves Henry
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034, Strasbourg Cedex 2, France
| | - Jean-François Dayen
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034, Strasbourg Cedex 2, France
| | - David Halley
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034, Strasbourg Cedex 2, France
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Lorchat E, Froehlicher G, Berciaud S. Splitting of Interlayer Shear Modes and Photon Energy Dependent Anisotropic Raman Response in N-Layer ReSe₂ and ReS₂. ACS Nano 2016; 10:2752-2760. [PMID: 26820232 DOI: 10.1021/acsnano.5b07844] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We investigate the interlayer phonon modes in N-layer rhenium diselenide (ReSe2) and rhenium disulfide (ReS2) by means of ultralow-frequency micro-Raman spectroscopy. These transition metal dichalcogenides exhibit a stable distorted octahedral (1T') phase with significant in-plane anisotropy, leading to sizable splitting of the (in-plane) layer shear modes. The fan-diagrams associated with the measured frequencies of the interlayer shear modes and the (out-of-plane) interlayer breathing modes are perfectly described by a finite linear chain model and allow the determination of the interlayer force constants. Nearly identical values are found for ReSe2 and ReS2. The latter are appreciably smaller than but on the same order of magnitude as the interlayer force constants reported in graphite and in trigonal prismatic (2Hc) transition metal dichalcogenides (such as MoS2, MoSe2, MoTe2, WS2, WSe2), demonstrating the importance of van der Waals interactions in N-layer ReSe2 and ReS2. In-plane anisotropy results in a complex angular dependence of the intensity of all Raman modes, which can be empirically utilized to determine the crystal orientation. However, we also demonstrate that the angular dependence of the Raman response drastically depends on the incoming photon energy, shedding light on the importance of resonant exciton-phonon coupling in ReSe2 and ReS2.
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Affiliation(s)
- Etienne Lorchat
- Institut de Physique et Chimie des Matériaux de Strasbourg and NIE, UMR 7504, Université de Strasbourg and CNRS , 23 rue du Lœss, BP43, Strasbourg 67034 Cedex 2, France
| | - Guillaume Froehlicher
- Institut de Physique et Chimie des Matériaux de Strasbourg and NIE, UMR 7504, Université de Strasbourg and CNRS , 23 rue du Lœss, BP43, Strasbourg 67034 Cedex 2, France
| | - Stéphane Berciaud
- Institut de Physique et Chimie des Matériaux de Strasbourg and NIE, UMR 7504, Université de Strasbourg and CNRS , 23 rue du Lœss, BP43, Strasbourg 67034 Cedex 2, France
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13
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Froehlicher G, Lorchat E, Fernique F, Joshi C, Molina-Sánchez A, Wirtz L, Berciaud S. Unified Description of the Optical Phonon Modes in N-Layer MoTe2. Nano Lett 2015; 15:6481-6489. [PMID: 26371970 DOI: 10.1021/acs.nanolett.5b02683] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
N-layer transition metal dichalcogenides provide a unique platform to investigate the evolution of the physical properties between the bulk (three-dimensional) and monolayer (quasi-two-dimensional) limits. Here, using high-resolution micro-Raman spectroscopy, we report a unified experimental description of the Γ-point optical phonons in N-layer 2H-molybdenum ditelluride (MoTe2). We observe series of N-dependent low-frequency interlayer shear and breathing modes (below 40 cm(-1), denoted LSM and LBM) and well-defined Davydov splittings of the mid-frequency modes (in the range 100-200 cm(-1), denoted iX and oX), which solely involve displacements of the chalcogen atoms. In contrast, the high-frequency modes (in the range 200-300 cm(-1), denoted iMX and oMX), arising from displacements of both the metal and chalcogen atoms, exhibit considerably reduced splittings. The manifold of phonon modes associated with the in-plane and out-of-plane displacements are quantitatively described by a force constant model, including interactions up to the second nearest neighbor and surface effects as fitting parameters. The splittings for the iX and oX modes observed in N-layer crystals are directly correlated to the corresponding bulk Davydov splittings between the E2u/E1g and B1u/A1g modes, respectively, and provide a measurement of the frequencies of the bulk silent E2u and B1u optical phonon modes. Our analysis could readily be generalized to other layered crystals.
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Affiliation(s)
- Guillaume Froehlicher
- Institut de Physique et Chimie des Matériaux de Strasbourg and NIE, UMR 7504, Université de Strasbourg and CNRS, 23 rue du Lœss, BP43, 67034 Strasbourg Cedex 2, France
| | - Etienne Lorchat
- Institut de Physique et Chimie des Matériaux de Strasbourg and NIE, UMR 7504, Université de Strasbourg and CNRS, 23 rue du Lœss, BP43, 67034 Strasbourg Cedex 2, France
| | - François Fernique
- Institut de Physique et Chimie des Matériaux de Strasbourg and NIE, UMR 7504, Université de Strasbourg and CNRS, 23 rue du Lœss, BP43, 67034 Strasbourg Cedex 2, France
| | - Chaitanya Joshi
- Physics and Materials Science Research Unit, University of Luxembourg , 162a avenue de la Faïencerie, L-1511 Luxembourg, Luxembourg
- Department of Physics, Indian Institute of Technology Bombay , Powai, Mumbai 400076, India
| | - Alejandro Molina-Sánchez
- Physics and Materials Science Research Unit, University of Luxembourg , 162a avenue de la Faïencerie, L-1511 Luxembourg, Luxembourg
| | - Ludger Wirtz
- Physics and Materials Science Research Unit, University of Luxembourg , 162a avenue de la Faïencerie, L-1511 Luxembourg, Luxembourg
| | - Stéphane Berciaud
- Institut de Physique et Chimie des Matériaux de Strasbourg and NIE, UMR 7504, Université de Strasbourg and CNRS, 23 rue du Lœss, BP43, 67034 Strasbourg Cedex 2, France
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14
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Affiliation(s)
- P Pillet
- Service de pédiatrie médicale, Hôpital des Enfants, 33076 Bordeaux cedex, France; Centre de compétence Arthrites Juvéniles Idiopathiques et Maladies Auto-inflammatoires de l'enfant, Hôpital Pellegrin-Enfants, Place Amélie Raba Léon 33076 Bordeaux cedex, France.
| | - M Lagarde
- Service de pédiatrie médicale, Hôpital des Enfants, 33076 Bordeaux cedex, France
| | - M Bailhache
- Service de pédiatrie médicale, Hôpital des Enfants, 33076 Bordeaux cedex, France
| | - S Berciaud
- Service de pédiatrie médicale, Hôpital des Enfants, 33076 Bordeaux cedex, France
| | - O Richer
- Service de pédiatrie médicale, Hôpital des Enfants, 33076 Bordeaux cedex, France; Centre de compétence Arthrites Juvéniles Idiopathiques et Maladies Auto-inflammatoires de l'enfant, Hôpital Pellegrin-Enfants, Place Amélie Raba Léon 33076 Bordeaux cedex, France
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15
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Faugeras C, Berciaud S, Leszczynski P, Henni Y, Nogajewski K, Orlita M, Taniguchi T, Watanabe K, Forsythe C, Kim P, Jalil R, Geim AK, Basko DM, Potemski M. Landau level spectroscopy of electron-electron interactions in graphene. Phys Rev Lett 2015; 114:126804. [PMID: 25860767 DOI: 10.1103/physrevlett.114.126804] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Indexed: 06/04/2023]
Abstract
We present magneto-Raman scattering studies of electronic inter-Landau level excitations in quasineutral graphene samples with different strengths of Coulomb interaction. The band velocity associated with these excitations is found to depend on the dielectric environment, on the index of Landau level involved, and to vary as a function of the magnetic field. This contradicts the single-particle picture of noninteracting massless Dirac electrons but is accounted for by theory when the effect of electron-electron interaction is taken into account. Raman active, zero-momentum inter-Landau level excitations in graphene are sensitive to electron-electron interactions due to the nonapplicability of the Kohn theorem in this system, with a clearly nonparabolic dispersion relation.
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Affiliation(s)
- C Faugeras
- Laboratoire National des Champs Magnétiques Intenses, CNRS, (UJF, UPS, INSA), BP 166, 38042 Grenoble, Cedex 9, France
| | - S Berciaud
- Institut de Physique et Chimie des Matériaux de Strasbourg and NIE, UMR 7504, Université de Strasbourg and CNRS, BP43, 67034 Strasbourg, Cedex 2, France
| | - P Leszczynski
- Laboratoire National des Champs Magnétiques Intenses, CNRS, (UJF, UPS, INSA), BP 166, 38042 Grenoble, Cedex 9, France
| | - Y Henni
- Laboratoire National des Champs Magnétiques Intenses, CNRS, (UJF, UPS, INSA), BP 166, 38042 Grenoble, Cedex 9, France
| | - K Nogajewski
- Laboratoire National des Champs Magnétiques Intenses, CNRS, (UJF, UPS, INSA), BP 166, 38042 Grenoble, Cedex 9, France
| | - M Orlita
- Laboratoire National des Champs Magnétiques Intenses, CNRS, (UJF, UPS, INSA), BP 166, 38042 Grenoble, Cedex 9, France
| | - T Taniguchi
- National Institute for Material Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - K Watanabe
- National Institute for Material Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - C Forsythe
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - P Kim
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - R Jalil
- School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom
| | - A K Geim
- School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom
| | - D M Basko
- Université Grenoble 1/CNRS, Laboratoire de Physique et de Modélisation des Milieux Condensés (UMR 5493), B.P. 166, 38042 Grenoble, Cedex 9, France
| | - M Potemski
- Laboratoire National des Champs Magnétiques Intenses, CNRS, (UJF, UPS, INSA), BP 166, 38042 Grenoble, Cedex 9, France
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16
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Federspiel F, Froehlicher G, Nasilowski M, Pedetti S, Mahmood A, Doudin B, Park S, Lee JO, Halley D, Dubertret B, Gilliot P, Berciaud S. Distance dependence of the energy transfer rate from a single semiconductor nanostructure to graphene. Nano Lett 2015; 15:1252-8. [PMID: 25607231 DOI: 10.1021/nl5044192] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The near-field Coulomb interaction between a nanoemitter and a graphene monolayer results in strong Förster-type resonant energy transfer and subsequent fluorescence quenching. Here, we investigate the distance dependence of the energy transfer rate from individual, (i) zero-dimensional CdSe/CdS nanocrystals and (ii) two-dimensional CdSe/CdS/ZnS nanoplatelets to a graphene monolayer. For increasing distances d, the energy transfer rate from individual nanocrystals to graphene decays as 1/d(4). In contrast, the distance dependence of the energy transfer rate from a two-dimensional nanoplatelet to graphene deviates from a simple power law but is well described by a theoretical model, which considers a thermal distribution of free excitons in a two-dimensional quantum well. Our results show that accurate distance measurements can be performed at the single particle level using graphene-based molecular rulers and that energy transfer allows probing dimensionality effects at the nanoscale.
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Affiliation(s)
- François Federspiel
- Institut de Physique et Chimie des Matériaux de Strasbourg and NIE, UMR 7504, Université de Strasbourg and CNRS , 23 rue du Lœss, BP43, 67034 Strasbourg Cedex 2, France
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17
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Berciaud S, Potemski M, Faugeras C. Probing electronic excitations in mono- to pentalayer graphene by micro magneto-Raman spectroscopy. Nano Lett 2014; 14:4548-4553. [PMID: 24955484 DOI: 10.1021/nl501578m] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We probe electronic excitations between Landau levels in freestanding N-layer graphene over a broad energy range, with unprecedented spectral and spatial resolution, using micro magneto-Raman scattering spectroscopy. A characteristic evolution of electronic bands in up to five Bernal-stacked graphene layers is evidenced and shown to remarkably follow a simple theoretical approach, based on an effective bilayer model. (N > 3)-layer graphenes appear as appealing candidates in the quest for novel phenomena, particularly in the quantum Hall effect regime. Our work paves the way toward minimally invasive investigations of magneto-excitons in other emerging low-dimensional systems, with a spatial resolution down to 1 μm.
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Affiliation(s)
- Stéphane Berciaud
- Institut de Physique et Chimie des Matériaux de Strasbourg and NIE, UMR 7504, Université de Strasbourg and CNRS , 23 rue du Lœss, BP43, 67034 Strasbourg Cedex 2, France
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Halley D, Najjari N, Majjad H, Joly L, Ohresser P, Scheurer F, Ulhaq-Bouillet C, Berciaud S, Doudin B, Henry Y. Size-induced enhanced magnetoelectric effect and multiferroicity in chromium oxide nanoclusters. Nat Commun 2014; 5:3167. [PMID: 24452260 DOI: 10.1038/ncomms4167] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 12/20/2013] [Indexed: 11/09/2022] Open
Abstract
The control of the magnetization of a material with an electric field would make the design and the integration of novel electronic devices possible. This explains the renewed interest in multiferroic materials. Progress in this field is currently hampered by the scarcity of the materials available and the smallness of the magnetoelectric effects. Here we present a proof-of-principle experiment showing that engineering large strains through nanoscale size reduction is an efficient route for increasing magnetoelectric coefficients by orders of magnitude. The archetype magnetoelectric material, Cr2O3, in the form of epitaxial clusters, exhibits an unprecedented 600% change in magnetization magnitude under 1 V. Furthermore, a multiferroic phase, with both magnetic and electric spontaneous polarizations, is found in the clusters, while absent in the bulk.
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Affiliation(s)
- D Halley
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2, France
| | - N Najjari
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2, France
| | - H Majjad
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2, France
| | - L Joly
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2, France
| | - P Ohresser
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette, France
| | - F Scheurer
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2, France
| | - C Ulhaq-Bouillet
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2, France
| | - S Berciaud
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2, France
| | - B Doudin
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2, France
| | - Y Henry
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2, France
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Godel F, Pichonat E, Vignaud D, Majjad H, Metten D, Henry Y, Berciaud S, Dayen JF, Halley D. Epitaxy of MgO magnetic tunnel barriers on epitaxial graphene. Nanotechnology 2013; 24:475708. [PMID: 24192567 DOI: 10.1088/0957-4484/24/47/475708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Epitaxial growth of electrodes and tunnel barriers on graphene is one of the main technological bottlenecks for graphene spintronics. In this paper, we demonstrate that MgO(111) epitaxial tunnel barriers, one of the prime candidates for spintronic application, can be grown by molecular beam epitaxy on epitaxial graphene on SiC(0001). Ferromagnetic metals (Fe, Co, Fe20Ni80) were epitaxially grown on top of the MgO barrier, thus leading to monocrystalline electrodes on graphene. Structural and magnetic characterizations were performed on these ferromagnetic metals after annealing and dewetting: they form clusters with a 100 nm typical lateral width, which are mostly magnetic monodomains in the case of Fe. This epitaxial stack opens the way to graphene spintronic devices taking benefits from a coherent tunnelling current through the epitaxial MgO/graphene stack.
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Berciaud S, Li X, Htoon H, Brus LE, Doorn SK, Heinz TF. Intrinsic line shape of the Raman 2D-mode in freestanding graphene monolayers. Nano Lett 2013; 13:3517-3523. [PMID: 23799800 DOI: 10.1021/nl400917e] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report a comprehensive study of the two-phonon intervalley (2D) Raman mode in graphene monolayers, motivated by recent reports of asymmetric 2D-mode line shapes in freestanding graphene. For photon energies in the range 1.53-2.71 eV, the 2D-mode Raman response of freestanding samples appears as bimodal, in stark contrast with the Lorentzian approximation that is commonly used for supported monolayers. The transition between the freestanding and supported cases is mimicked by electrostatically doping freestanding graphene at carrier densities above 2 × 10(11) cm(-2). This result quantitatively demonstrates that low levels of charging can obscure the intrinsically bimodal 2D-mode line shape of monolayer graphene. In pristine freestanding graphene, we observe a broadening of the 2D-mode feature with decreasing photon energy that cannot be rationalized using a simple one-dimensional model based on resonant inner and outer processes. This indicates that phonon wavevectors away from the high-symmetry lines of the Brillouin zone must contribute to the 2D-mode, so that a full two-dimensional calculation is required to properly describe multiphonon-resonant Raman processes.
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Affiliation(s)
- Stéphane Berciaud
- Institut de Physique et Chimie des Matériaux de Strasbourg and NIE, UMR 7504, Université de Strasbourg and CNRS, Strasbourg, France.
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Richer O, Coupet A, Berciaud S, Pillet P. Atteintes rhumatologiques : Quand évoquer et ne pas évoquer une maladie de Lyme ? Arch Pediatr 2013. [DOI: 10.1016/s0929-693x(13)71299-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Berciaud S, Rayne F, Kassab S, Jubert C, Faure-Della Corte M, Salin F, Wodrich H, Lafon ME. Adenovirus infections in Bordeaux University Hospital 2008-2010: clinical and virological features. J Clin Virol 2012; 54:302-7. [PMID: 22608365 DOI: 10.1016/j.jcv.2012.04.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 04/06/2012] [Accepted: 04/17/2012] [Indexed: 10/28/2022]
Abstract
BACKGROUND Transversal epidemiological data on adenovirus infections in a hospital setting, including both immuno-competent and transplanted patients, are limited and rarely contain the application of molecular virology. OBJECTIVES To describe the clinical characteristics and molecular epidemiology of adenovirus infections in Bordeaux University Hospital from 2008 to 2010 (clinical data, viral load and adenovirus species distribution). STUDY DESIGN Adenovirus DNA quantification (qPCR) and typing (sequencing of hexon and protein VI genes and protein VI polymerase chain reaction (PCR) product analysis) were applied retrospectively to 215 clinical samples from 105 adenovirus-infected patients (2008-2010, Bordeaux University Hospital). Clinical data were recovered and analysed for 73 children and 25 adults. RESULTS Viral loads were measured in stools, upper and lower respiratory fluids, blood, urine and digestive tract biopsies; the highest values were observed in stools and respiratory samples. Stool viral loads were comparable whatever the immune status. Adenovirus was typed in 57 patients: species Human adenovirus (HAdV) C dominated (n=36), followed by B (n=15), F (n=5) and D (n=1). We could demonstrate no association between HAdV species and load or clinical severity (observed in most patients). In the immuno-compromised, in contrast to immuno-competent patients, adenovirus infections presented no seasonal variation. Co-infections were frequent: mostly bacterial in immuno-competent children (33%) and viral in immuno-compromised people (34%). CONCLUSIONS The species HAdV C dominates the local ecology, in both respiratory and digestive tract infections, independently of the patient's immune status. Adenovirus infections, often associated with co-infection of bacterial or viral agents, frequently lead to severe clinical consequences in hospital patients.
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Affiliation(s)
- S Berciaud
- Centre Hospitalier Universitaire de Bordeaux, Pediatrics Department, France
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23
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Santos SM, Yuma B, Berciaud S, Shaver J, Gallart M, Gilliot P, Cognet L, Lounis B. All-optical trion generation in single-walled carbon nanotubes. Phys Rev Lett 2011; 107:187401. [PMID: 22107671 DOI: 10.1103/physrevlett.107.187401] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2011] [Indexed: 05/31/2023]
Abstract
We present evidence of all-optical trion generation and emission in pristine single-walled carbon nanotubes (SWCNTs). Luminescence spectra, recorded on individual SWCNTs over a large cw excitation intensity range, show trion emission peaks redshifted with respect to the bright exciton peak. Clear chirality dependence is observed for 22 separate SWCNT species, allowing for determination of electron-hole exchange interaction and trion binding energy contributions. Luminescence data together with ultrafast pump-probe experiments on chirality-sorted bulk samples suggest that exciton-exciton annihilation processes generate dissociated carriers that allow for trion creation upon a subsequent photon absorption event.
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Affiliation(s)
- Silvia M Santos
- LP2N, Université de Bordeaux, Institut d'Optique and CNRS, 351 Cours de la Libération, 33405 Talence, France
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24
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Farhat H, Berciaud S, Kalbac M, Saito R, Heinz TF, Dresselhaus MS, Kong J. Observation of electronic Raman scattering in metallic carbon nanotubes. Phys Rev Lett 2011; 107:157401. [PMID: 22107317 DOI: 10.1103/physrevlett.107.157401] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Indexed: 05/31/2023]
Abstract
We present experimental measurements of the electronic contribution to the Raman spectra of individual metallic single-walled carbon nanotubes (MSWNTs). Photoexcited carriers are inelastically scattered by a continuum of low-energy electron-hole pairs created across the graphenelike linear electronic subbands of the MSWNTs. The optical resonances in MSWNTs give rise to well-defined electronic Raman peaks. This resonant electronic Raman scattering is a unique feature of the electronic structure of these one-dimensional quasimetals.
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Affiliation(s)
- H Farhat
- Research Laboratory of Electronics, MIT, Cambridge, Massachusetts 02139, USA
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25
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Chandra B, Perebeinos V, Berciaud S, Katoch J, Ishigami M, Kim P, Heinz TF, Hone J. Low bias electron scattering in structure-identified single wall carbon nanotubes: role of substrate polar phonons. Phys Rev Lett 2011; 107:146601. [PMID: 22107221 DOI: 10.1103/physrevlett.107.146601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Indexed: 05/31/2023]
Abstract
We have performed temperature-dependent electrical transport measurements on known structure single wall carbon nanotubes at low bias. The experiments show a superlinear increase in nanotube resistivity with temperature, which is in contradiction with the linear dependence expected from nanotube acoustic-phonon scattering. The measured electron mean free path is also much lower than expected, especially at medium to high temperatures (>100 K). A theoretical model that includes scattering due to surface polar phonon modes of the substrates reproduces the experiments very well. The role of surface phonons is further confirmed by resistivity measurements of nanotubes on aluminum nitride.
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Affiliation(s)
- Bhupesh Chandra
- Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA.
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26
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Berciaud S, Han MY, Mak KF, Brus LE, Kim P, Heinz TF. Electron and optical phonon temperatures in electrically biased graphene. Phys Rev Lett 2010; 104:227401. [PMID: 20867202 DOI: 10.1103/physrevlett.104.227401] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Indexed: 05/23/2023]
Abstract
We examine the intrinsic energy dissipation steps in electrically biased graphene channels. By combining in-situ measurements of the spontaneous optical emission with a Raman spectroscopy study of the graphene sample under conditions of current flow, we obtain independent information on the energy distribution of the electrons and phonons. The electrons and holes contributing to light emission are found to obey a thermal distribution, with temperatures in excess of 1500 K in the regime of current saturation. The zone-center optical phonons are also highly excited and are found to be in equilibrium with the electrons. For a given optical phonon temperature, the anharmonic downshift of the Raman G mode is smaller than expected under equilibrium conditions, suggesting that the electrons and high-energy optical phonons are not fully equilibrated with all of the phonon modes.
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Affiliation(s)
- Stéphane Berciaud
- Department of Physics, Columbia University, New York, New York 10027, USA.
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27
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Chen Z, Berciaud S, Nuckolls C, Heinz TF, Brus LE. Energy transfer from individual semiconductor nanocrystals to graphene. ACS Nano 2010; 4:2964-8. [PMID: 20402475 DOI: 10.1021/nn1005107] [Citation(s) in RCA: 171] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Energy transfer from photoexcited zero-dimensional systems to metallic systems plays a prominent role in modern day materials science. A situation of particular interest concerns the interaction between a photoexcited dipole and an atomically thin metal. The recent discovery of graphene layers permits investigation of this phenomenon. Here we report a study of fluorescence from individual CdSe/ZnS nanocrystals in contact with single- and few-layer graphene sheets. The rate of energy transfer is determined from the strong quenching of the nanocrystal fluorescence. For single-layer graphene, we find a rate of approximately 4 ns(-1), in agreement with a model based on the dipole approximation and a tight-binding description of graphene. This rate increases significantly with the number of graphene layers, before approaching the bulk limit. Our study quantifies energy transfer to and fluorescence quenching by graphene, critical properties for novel applications in photovoltaic devices and as a molecular ruler.
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Affiliation(s)
- Zheyuan Chen
- Department of Chemistry, Columbia University, New York, New York 10027, USA
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28
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Berciaud S, Ryu S, Brus LE, Heinz TF. Probing the intrinsic properties of exfoliated graphene: Raman spectroscopy of free-standing monolayers. Nano Lett 2009; 9:346-352. [PMID: 19099462 DOI: 10.1021/nl8031444] [Citation(s) in RCA: 192] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The properties of pristine, free-standing graphene monolayers prepared by mechanical exfoliation of graphite are investigated. The graphene monolayers, suspended over open trenches, are examined by means of spatially resolved Raman spectroscopy of the G-, D-, and 2D-phonon modes. The G-mode phonons exhibit reduced energies (1580 cm(-1)) and increased widths (14 cm(-1)) compared to the response of graphene monolayers supported on the SiO(2)-covered substrate. From analysis of the G-mode Raman spectra, we deduce that the free-standing graphene monolayers are essentially undoped, with an upper bound of 2 x 10(11) cm(-2) for the residual carrier concentration. On the supported regions, significantly higher and spatially inhomogeneous doping is observed. The free-standing graphene monolayers show little local disorder, based on the very weak Raman D-mode response. The two-phonon 2D mode of the free-standing graphene monolayers is downshifted in frequency compared to that of the supported region of the samples and exhibits a narrowed, positively skewed line shape.
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Affiliation(s)
- Stéphane Berciaud
- Departments of Physics and Electrical Engineering and Department of Chemistry, Columbia University, New York, New York 10027, USA
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29
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Berciaud S, Cognet L, Lounis B. Luminescence decay and the absorption cross section of individual single-walled carbon nanotubes. Phys Rev Lett 2008; 101:077402. [PMID: 18764579 DOI: 10.1103/physrevlett.101.077402] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Indexed: 05/26/2023]
Abstract
The absorption cross section of highly luminescent individual single-walled carbon nanotubes is determined using time-resolved and cw luminescence spectroscopy. A mean value of approximately 1 x 10(-17) cm2 per carbon atom is obtained for (6,5) tubes excited at their second optical transition, and corroborated by single tube photothermal absorption measurements. Biexponential luminescence decays are systematically observed, with short and long lifetimes around 45 and 250 ps. This behavior is attributed to the band edge exciton fine structure with a dark level lying a few meV below a bright one.
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Affiliation(s)
- Stéphane Berciaud
- Centre de Physique Moléculaire Optique et Hertzienne, Université de Bordeaux and CNRS, 351 cours de la Libération, Talence, F-33405, France
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30
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Affiliation(s)
- Laurent Cognet
- Université Bordeaux 1 and Centre National de la Recherche Scientifique, France
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31
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Berciaud S, Cognet L, Poulin P, Weisman RB, Lounis B. Absorption spectroscopy of individual single-walled carbon nanotubes. Nano Lett 2007; 7:1203-7. [PMID: 17385932 DOI: 10.1021/nl062933k] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Current methods for producing single-walled carbon nanotubes (SWNTs) lead to heterogeneous samples containing mixtures of metallic and semiconducting species with a variety of lengths and defects. Optical detection at the single nanotube level should thus offer the possibility to examine these heterogeneities provided that both SWNT species are equally well detected. Here, we used photothermal heterodyne detection to record absorption images and spectra of individual SWNTs. Because this photothermal method relies only on light absorption, it readily detects metallic nanotubes as well as the emissive semiconducting species. The first and second optical transitions in individual semiconducting nanotubes have been probed. Comparison between the emission and absorption spectra of the lowest-lying optical transition reveal mainly small Stokes shifts. Side bands in the near-infrared absorption spectra are observed and assigned to exciton-phonon bound states. No such sidebands are detected around the lowest transition of metallic nanotubes.
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Affiliation(s)
- Stéphane Berciaud
- Centre de Physique Moléculaire Optique et Hertzienne, Université Bordeaux I and CNRS (UMR 5798), 351 cours de la Libération, 33405 Talence Cedex, France
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32
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Lasne D, Blab GA, Berciaud S, Heine M, Groc L, Choquet D, Cognet L, Lounis B. Single nanoparticle photothermal tracking (SNaPT) of 5-nm gold beads in live cells. Biophys J 2006; 91:4598-604. [PMID: 16997874 PMCID: PMC1779909 DOI: 10.1529/biophysj.106.089771] [Citation(s) in RCA: 204] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Tracking individual nano-objects in live cells during arbitrary long times is a ubiquitous need in modern biology. We present here a method for tracking individual 5-nm gold nanoparticles on live cells. It relies on the photothermal effect and the detection of the Laser Induced Scattering around a NanoAbsorber (LISNA). The key point for recording trajectories at video rate is the use of a triangulation procedure. The effectiveness of the method is tested against single fluorescent molecule tracking in live COS7 cells on subsecond timescales. We further demonstrate recordings for several minutes of AMPA receptors trajectories on the plasma membrane of live neurons. Single Nanoparticle Photothermal Tracking has the unique potential to record arbitrary long trajectory of membrane proteins using nonfluorescent nanometer-sized labels.
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Affiliation(s)
- David Lasne
- Centre de Physique Moléculaire Optique et Hertzienne, CNRS (UMR 5798) and Université Bordeaux 1, Talence Cedex, France
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33
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van Dijk MA, Tchebotareva AL, Orrit M, Lippitz M, Berciaud S, Lasne D, Cognet L, Lounis B. Absorption and scattering microscopy of single metal nanoparticles. Phys Chem Chem Phys 2006; 8:3486-95. [PMID: 16871337 DOI: 10.1039/b606090k] [Citation(s) in RCA: 170] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Several recently developed detection techniques opened studies of individual metal nanoparticles (1-100 nm in diameter) in the optical far field. Eliminating averaging over the broad size and shape distributions produced by even the best of current synthesis methods, these studies hold great promise for gaining a deeper insight into many of the properties of metal nanoparticles, notably electronic and vibrational relaxation. All methods are based on detection of a scattered wave emitted either by the particle itself, or by its close environment. Direct absorption and interference techniques rely on the particle's scattering and have similar limits in signal-to-noise ratio. The photothermal method uses a photo-induced change in the refractive index of the environment as an additional step to scatter a wave with a different wavelength. This leads to a considerable improvement in signal-to-background ratio, and thus to a much higher sensitivity. We briefly discuss and compare these various techniques, review the new results they generated so far, and conclude on their great potential for nanoscience and for single-molecule labelling in biological assays and live cells.
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Affiliation(s)
- M A van Dijk
- MoNOS, Huygens Laboratory, University of Leiden, P.O. Box 9504, 2300 RA Leiden, The Netherlands
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34
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Blab GA, Cognet L, Berciaud S, Alexandre I, Husar D, Remacle J, Lounis B. Optical readout of gold nanoparticle-based DNA microarrays without silver enhancement. Biophys J 2005; 90:L13-5. [PMID: 16284272 PMCID: PMC1367045 DOI: 10.1529/biophysj.105.076182] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We present a novel readout scheme for gold nanoparticle-based DNA microarrays relying on "Laser-Induced Scattering around a NanoAbsorber". It provides direct counting of individual nanoparticles present on each array spot and stable signals, without any silver enhancement. Given the detection of nanometer-sized particles, which minimize the steric hindrance, the linear dynamic range of the method is particularly large and well suited for microarray detection.
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Abstract
Photothermal heterodyne detection is used to record the first room-temperature absorption spectra of single CdSe/ZnS semiconductor nanocrystals. These spectra are recorded in the high cw excitation regime, and the observed bands are assigned to transitions involving biexciton and trion states. Comparison with the single nanocrystals photoluminescence spectra leads to the measurement of spectral Stokes shifts free from ensemble averaging.
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Affiliation(s)
- Stéphane Berciaud
- Centre de Physique Moléculaire Optique et Hertzienne, CNRS (UMR 5798) et Université Bordeaux I, 351, cours de la Libération, 33405 Talence Cedex, France
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36
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Berciaud S, Cognet L, Tamarat P, Lounis B. Observation of intrinsic size effects in the optical response of individual gold nanoparticles. Nano Lett 2005; 5:515-8. [PMID: 15755105 DOI: 10.1021/nl050062t] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The photothermal heterodyne imaging method is used to study for the first time the absorption spectra of individual gold nanoparticles with diameters down to 5 nm. Intrinsic size effects that result in a broadening of the surface plasmon resonance are unambiguously observed. Dispersions in the peak energies and homogeneous widths of the single-particle resonances are revealed. The experimental results are analyzed within the frame of Mie theory.
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Affiliation(s)
- Stéphane Berciaud
- Centre de Physique Moléculaire Optique et Hertzienne, CNRS (UMR 5798) et Université Bordeaux I, 351, cours de la Libération, 33405 Talence Cedex, France
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37
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Berciaud S, Cognet L, Blab GA, Lounis B. Photothermal heterodyne imaging of individual nonfluorescent nanoclusters and nanocrystals. Phys Rev Lett 2004; 93:257402. [PMID: 15697940 DOI: 10.1103/physrevlett.93.257402] [Citation(s) in RCA: 163] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2004] [Indexed: 05/22/2023]
Abstract
We introduce a new, highly sensitive, and simple heterodyne optical method for imaging individual nonfluorescent nanoclusters and nanocrystals. A 2 order of magnitude improvement of the signal is achieved compared to previous methods. This allows for the unprecedented detection of individual small absorptive objects such as metallic clusters (of 67 atoms) or nonluminescent semiconductor nanocrystals. The measured signals are in agreement with a calculation based on the scattering field theory from a photothermal-induced modulated index of refraction profile around the nanoparticle.
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Affiliation(s)
- Stéphane Berciaud
- Centre de Physique Moléculaire Optique et Hertzienne, CNRS (UMR 5798) et Université Bordeaux I, 351, cours de la Libération, 33405 Talence Cedex, France
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