1
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Vernier C, Saviot L, Fan Y, Courty A, Portalès H. Sensitivity of Localized Surface Plasmon Resonance and Acoustic Vibrations to Edge Rounding in Silver Nanocubes. ACS NANO 2023; 17:20462-20472. [PMID: 37812521 DOI: 10.1021/acsnano.3c06990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
Precise knowledge of the dependence of nano-object properties on their structural characteristics such as their size, shape, composition, or crystallinity, in turn, enables them to be finely characterized using appropriate techniques. Spectrophotometry and inelastic light scattering spectroscopy are noninvasive techniques that are proving highly robust and efficient for characterizing the optical response and vibrational properties of metal nano-objects. Here, we investigate the optical and vibrational properties of monodomain silver nanocubes synthesized by the chemical route, with edge length ranging from around 20 to 58 nm. The synthesized nanocrystals are not perfectly cubic and exhibit rounded edges and corners. This rounding was quantitatively taken into account by assimilating the shape of the nanocubes to superellipsoids. The effect of rounding on their optical response was clearly evidenced by localized surface plasmon resonance spectroscopy and supported by calculations based on the discrete dipole approximation method. The study of their acoustic vibrations by high-resolution low-frequency Raman scattering revealed a substructure of the T2g band, which was analyzed as a function of rounding. The measured frequencies are consistent with the existence of an anticrossing pattern of the two T2g branches. Such an avoided crossing in the T2g modes is clearly evidenced by calculating the vibrational frequencies of silver nanocubes using the Rayleigh-Ritz variational method that accounts for both their real size, shape, and cubic elasticity. These results show that it is possible to assess the rounding of nanocubes, including by means of ensemble spectroscopic measurements on well-calibrated particles.
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Affiliation(s)
- Charles Vernier
- Sorbonne Université, CNRS, MONARIS, UMR 8233, Paris 75005, France
| | - Lucien Saviot
- Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS, Université Bourgogne Franche-Comté, Dijon CEDEX 21078, France
| | - Yinan Fan
- Sorbonne Université, CNRS, MONARIS, UMR 8233, Paris 75005, France
| | - Alexa Courty
- Sorbonne Université, CNRS, MONARIS, UMR 8233, Paris 75005, France
| | - Hervé Portalès
- Sorbonne Université, CNRS, MONARIS, UMR 8233, Paris 75005, France
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2
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Liu Z, Li Y, Kahng E, Xue S, Du X, Li S, Jin R. Tailoring the Electron-Phonon Interaction in Au 25(SR) 18 Nanoclusters via Ligand Engineering and Insight into Luminescence. ACS NANO 2022; 16:18448-18458. [PMID: 36252530 DOI: 10.1021/acsnano.2c06586] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Understanding the electron-phonon interaction in Au nanoclusters (NCs) is essential for enhancing and tuning their photoluminescence (PL) properties. Among all the methods, ligand engineering is the most straightforward and facile one to design Au NCs with the desired PL properties. However, a systematic understanding of the ligand effects toward electron-phonon interactions in Au NCs is still missing. Herein, we synthesized four Au25(SR)18- NCs protected by different -SR ligands and carefully examined their temperature-dependent band-gap renormalization behavior. Data analysis by a Bose-Einstein two-oscillator model revealed a suppression of high-frequency optical phonons in aromatic-ligand-protected Au25 NCs. Meanwhile, a low-frequency breathing mode and a quadrupolar mode are attributed as the main contributors to the phonon-assisted nonradiative relaxation pathway in aromatic-ligand-protected Au25 NCs, which is in contrast with non-aromatic-ligand-protected Au25 NCs, in which tangential and radial modes play the key roles. The PL measurements of the four Au25 NCs showed that the suppression of optical phonons led to higher quantum yields in aromatic-ligand-protected Au25 NCs. Cryogenic PL measurements provide insights into the nonradiative energy relaxation, which should be further investigated for a full understanding of the PL mechanism in Au25 NCs.
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Affiliation(s)
- Zhongyu Liu
- Department of Chemistry, Carnegie Mellon University, PittsburghPennsylvania15213, United States
| | - Yingwei Li
- Department of Chemistry, Carnegie Mellon University, PittsburghPennsylvania15213, United States
| | - Ellen Kahng
- Department of Chemistry, Carnegie Mellon University, PittsburghPennsylvania15213, United States
| | - Shan Xue
- Department of Chemistry, Carnegie Mellon University, PittsburghPennsylvania15213, United States
| | - Xiangsha Du
- Department of Chemistry, Carnegie Mellon University, PittsburghPennsylvania15213, United States
| | - Site Li
- Department of Chemistry, Carnegie Mellon University, PittsburghPennsylvania15213, United States
| | - Rongchao Jin
- Department of Chemistry, Carnegie Mellon University, PittsburghPennsylvania15213, United States
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3
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Zhao X, Nie Z, Feng Y, Zhao W, Zhang J, Zhang W, Maioli P, Loh ZH. Ultrafast acoustic vibrations of Au-Ag nanoparticles with varying elongated structures. Phys Chem Chem Phys 2020; 22:22728-22735. [PMID: 33016284 DOI: 10.1039/d0cp03260c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Acoustic vibrations of Au and Ag elongated nano-objects with original morphologies, from Ag-Ag homodimers to Au@Ag-Ag heterodimers and Au@Ag eccentric core-shell spheroids, have been experimentally investigated by ultrafast time-resolved optical spectroscopy. Their frequencies, obtained by the analysis of time-dependent transient absorption changes, are compared with the results obtained from finite element modeling (FEM) numerical computations, which allow assignment of the detected oscillating signals to fundamental radial and extensional modes. FEM was further used to analyze the effects of morphology and composition on the vibrational dynamics. FEM computations indicate that (1) the central distance between particles forming the nanodimers has profound effects on the extensional mode frequencies and a negligible influence on the radial mode ones, in analogy with the case of monometallic nanorods, (2) coating Au with Ag also has a strong mass-loading-like effect on the dimer and core-shell stretching mode frequency, while (3) its influence on the radial breathing mode is smaller and analogous to the non-monotonic frequency dependence on the Au fraction previously observed in isotropic bimetallic spheres. These findings are significant for developing a predictive understanding of nanostructure mechanical properties and for designing new mechanical nanoresonators.
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Affiliation(s)
- Xin Zhao
- School of Physics and Optoelectronic Engineering, Guangdong University of Technology, Guangzhou 510006, Guangdong, China.
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4
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Ostovar B, Su MN, Renard D, Clark BD, Dongare PD, Dutta C, Gross N, Sader JE, Landes CF, Chang WS, Halas NJ, Link S. Acoustic Vibrations of Al Nanocrystals: Size, Shape, and Crystallinity Revealed by Single-Particle Transient Extinction Spectroscopy. J Phys Chem A 2020; 124:3924-3934. [PMID: 32286064 DOI: 10.1021/acs.jpca.0c01190] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Acoustic vibrations in plasmonic nanoparticles, monitored by an all-optical means, have attracted significant increasing interest because they provide unique insight into the mechanical properties of these metallic nanostructures. Al nanostructures are a recently emerging alternative to noble metal nanoparticles, because their broad wavelength tunability and high natural abundance make them ideal for many potential applications. Here, we investigate the acoustic vibrations of individual Al nanocrystals using a combination of electron microscopy and single-particle transient extinction spectroscopy, made possible with a low-pulse energy, high sensitivity, and probe-wavelength-tunable, single-particle transient extinction microscope. For chemically synthesized, faceted Al nanocrystals, the observed vibration frequency scales with the inverse particle diameter. In contrast, triangularly shaped Al nanocrystals support two distinct frequencies, corresponding to their in- and out-of-plane breathing modes. Unlike ensemble measurements, which measure average properties, measuring the damping time of the acoustic vibrations for individual particles enables us to investigate variations of the quality factor on the particle-to-particle level. Surprisingly, we find a large variation in quality factors even for nanocrystals of similar size and shape. This observed heterogeneity appears to result from substantially varying degrees of nanoparticle crystallinity even for chemically synthesized nanocrystals.
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Affiliation(s)
| | | | | | | | | | | | | | - John E Sader
- ARC Centre of Excellence in Exciton Science, School of Mathematics and Statistics, The University of Melbourne, Parkville, VIC 3010, Australia
| | | | - Wei-Shun Chang
- Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, Massachusetts 02747, United States
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5
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Gan Y, Sun Z. Crystal structure dependence of the breathing vibration of individual gold nanodisks induced by the ultrafast laser. APPLIED OPTICS 2019; 58:213-218. [PMID: 30645531 DOI: 10.1364/ao.58.000213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 11/29/2018] [Indexed: 06/09/2023]
Abstract
The ultrafast laser-excited breathing vibrations of gold nanodisks with different crystal structures have been studied via atomistic simulations. The vibrational periods and damping rates of nanodisks are obtained by the analysis of the simulated transient responses of nanodisks. It is shown that the breathing period of nanodisks is considerably dependent on their crystal structure, which is contrary to the cases for the breathing vibration of metal nanospheres and nanorods. Furthermore, single-crystal nanodisks exhibit much lower intrinsic damping as compared with polycrystalline nanodisks, for which the additional energy dissipation by the grain boundaries in the polycrystalline nanodisks could be one major factor.
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6
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Maioli P, Stoll T, Sauceda HE, Valencia I, Demessence A, Bertorelle F, Crut A, Vallée F, Garzón IL, Cerullo G, Del Fatti N. Mechanical Vibrations of Atomically Defined Metal Clusters: From Nano- to Molecular-Size Oscillators. NANO LETTERS 2018; 18:6842-6849. [PMID: 30247927 DOI: 10.1021/acs.nanolett.8b02717] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Acoustic vibrations of small nanoparticles are still ruled by continuum mechanics laws down to diameters of a few nanometers. The elastic behavior at lower sizes (<1-2 nm), where nanoparticles become molecular clusters made by few tens to few atoms, is still little explored. The question remains to which extent the transition from small continuous-mass solids to discrete-atom molecular clusters affects their specific low-frequency vibrational modes, whose period is classically expected to linearly scale with diameter. Here, we investigate experimentally by ultrafast time-resolved optical spectroscopy the acoustic response of atomically defined ligand-protected metal clusters Au n(SR) m with a number n of atoms ranging from 10 to 102 (0.5-1.5 nm diameter range). Two periods, corresponding to fundamental breathing- and quadrupolar-like acoustic modes, are detected, with the latter scaling linearly with cluster diameters and the former taking a constant value. Theoretical calculations based on density functional theory (DFT) predict in the case of bare clusters vibrational periods scaling with size down to diatomic molecules. For ligand-protected clusters, they show a pronounced effect of the ligand molecules on the breathing-like mode vibrational period at the origin of its constant value. This deviation from classical elasticity predictions results from mechanical mass-loading effects due to the protecting layer. This study shows that clusters characteristic vibrational frequencies are compatible with extrapolation of continuum mechanics model down to few atoms, which is in agreement with DFT computations.
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Affiliation(s)
- Paolo Maioli
- Institut Lumière Matière , Université de Lyon, CNRS, Université Claude Bernard Lyon 1 , F-69622 Villeurbanne , France
| | - Tatjana Stoll
- Institut Lumière Matière , Université de Lyon, CNRS, Université Claude Bernard Lyon 1 , F-69622 Villeurbanne , France
- Dipartimento di Fisica, Politecnico di Milano , IFN-CNR , Piazza L. da Vinci 32 , I-20133 Milano , Italy
| | - Huziel E Sauceda
- Fritz-Haber-Institute der Max-Planck-Gesellschaft , 14195 Berlin , Germany
| | - Israel Valencia
- Facultad de Estudios Superiores-Iztacala , Universidad Nacional Autónoma de México , 54090 Tlanepantla , Estado de México México
| | - Aude Demessence
- Institut de Recherches sur la Catalyse et l'Environnement de Lyon (IRCELYON) , Université de Lyon, CNRS, Université Claude Bernard Lyon 1 , F-69622 Villeurbanne , France
| | - Franck Bertorelle
- Institut Lumière Matière , Université de Lyon, CNRS, Université Claude Bernard Lyon 1 , F-69622 Villeurbanne , France
| | - Aurélien Crut
- Institut Lumière Matière , Université de Lyon, CNRS, Université Claude Bernard Lyon 1 , F-69622 Villeurbanne , France
| | - Fabrice Vallée
- Institut Lumière Matière , Université de Lyon, CNRS, Université Claude Bernard Lyon 1 , F-69622 Villeurbanne , France
| | - Ignacio L Garzón
- Instituto de Física , Universidad Nacional Autónoma de México , Apartado Postal 20-364, 01000 CDMX , México
| | - Giulio Cerullo
- Dipartimento di Fisica, Politecnico di Milano , IFN-CNR , Piazza L. da Vinci 32 , I-20133 Milano , Italy
| | - Natalia Del Fatti
- Institut Lumière Matière , Université de Lyon, CNRS, Université Claude Bernard Lyon 1 , F-69622 Villeurbanne , France
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7
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Yi C, Su MN, Dongare PD, Chakraborty D, Cai YY, Marolf DM, Kress RN, Ostovar B, Tauzin LJ, Wen F, Chang WS, Jones MR, Sader JE, Halas NJ, Link S. Polycrystallinity of Lithographically Fabricated Plasmonic Nanostructures Dominates Their Acoustic Vibrational Damping. NANO LETTERS 2018; 18:3494-3501. [PMID: 29715035 DOI: 10.1021/acs.nanolett.8b00559] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The study of acoustic vibrations in nanoparticles provides unique and unparalleled insight into their mechanical properties. Electron-beam lithography of nanostructures allows precise manipulation of their acoustic vibration frequencies through control of nanoscale morphology. However, the dissipation of acoustic vibrations in this important class of nanostructures has not yet been examined. Here we report, using single-particle ultrafast transient extinction spectroscopy, the intrinsic damping dynamics in lithographically fabricated plasmonic nanostructures. We find that in stark contrast to chemically synthesized, monocrystalline nanoparticles, acoustic energy dissipation in lithographically fabricated nanostructures is solely dominated by intrinsic damping. A quality factor of Q = 11.3 ± 2.5 is observed for all 147 nanostructures, regardless of size, geometry, frequency, surface adhesion, and mode. This result indicates that the complex Young's modulus of this material is independent of frequency with its imaginary component being approximately 11 times smaller than its real part. Substrate-mediated acoustic vibration damping is strongly suppressed, despite strong binding between the glass substrate and Au nanostructures. We anticipate that these results, characterizing the optomechanical properties of lithographically fabricated metal nanostructures, will help inform their design for applications such as photoacoustic imaging agents, high-frequency resonators, and ultrafast optical switches.
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Affiliation(s)
- Chongyue Yi
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States
| | - Man-Nung Su
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States
| | - Pratiksha D Dongare
- Applied Physics Graduate Program , Rice University , Houston , Texas 77005 , United States
- Department of Electrical and Computer Engineering , Rice University , Houston , Texas 77005 , United States
| | - Debadi Chakraborty
- ARC Centre of Excellence in Exciton Science, School of Mathematics and Statistics , The University of Melbourne , Parkville , VIC 3010 , Australia
| | - Yi-Yu Cai
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States
| | - David M Marolf
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States
| | - Rachael N Kress
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States
| | - Behnaz Ostovar
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States
| | - Lawrence J Tauzin
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States
| | - Fangfang Wen
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States
| | - Wei-Shun Chang
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States
| | - Matthew R Jones
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States
| | - John E Sader
- ARC Centre of Excellence in Exciton Science, School of Mathematics and Statistics , The University of Melbourne , Parkville , VIC 3010 , Australia
| | - Naomi J Halas
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States
- Department of Electrical and Computer Engineering , Rice University , Houston , Texas 77005 , United States
- Department of Physics and Astronomy , Rice University , Houston , Texas 77005 , United States
- Laboratory for Nanophotonics , Rice University , Houston , Texas 77005 , United States
| | - Stephan Link
- Department of Chemistry , Rice University , Houston , Texas 77005 , United States
- Department of Electrical and Computer Engineering , Rice University , Houston , Texas 77005 , United States
- Laboratory for Nanophotonics , Rice University , Houston , Texas 77005 , United States
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8
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Devkota T, Chakraborty D, Yu K, Beane G, Sader JE, Hartland GV. On the measurement of relaxation times of acoustic vibrations in metal nanowires. Phys Chem Chem Phys 2018; 20:17687-17693. [DOI: 10.1039/c8cp03230k] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Energy relaxation of the breathing modes of metal nanostructures is controlled by radiation of sound waves in the environment.
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Affiliation(s)
- Tuphan Devkota
- Department of Chemistry and Biochemistry
- University of Notre Dame
- Notre Dame
- Indiana 46556
- USA
| | - Debadi Chakraborty
- ARC Centre of Excellence in Exciton Science
- School of Mathematics and Statistics
- The University of Melbourne
- Victoria 3010
- Australia
| | - Kuai Yu
- College of Electronic Science and Technology
- Shenzhen University
- Shenzhen
- P. R. China
| | - Gary Beane
- Department of Chemistry and Biochemistry
- University of Notre Dame
- Notre Dame
- Indiana 46556
- USA
| | - John E. Sader
- ARC Centre of Excellence in Exciton Science
- School of Mathematics and Statistics
- The University of Melbourne
- Victoria 3010
- Australia
| | - Gregory V. Hartland
- Department of Chemistry and Biochemistry
- University of Notre Dame
- Notre Dame
- Indiana 46556
- USA
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9
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Ahmed A, Pelton M, Guest JR. Understanding How Acoustic Vibrations Modulate the Optical Response of Plasmonic Metal Nanoparticles. ACS NANO 2017; 11:9360-9369. [PMID: 28817767 DOI: 10.1021/acsnano.7b04789] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Measurements of acoustic vibrations in nanoparticles provide an opportunity to study mechanical phenomena at nanometer length scales and picosecond time scales. Vibrations in noble-metal nanoparticles have attracted particular attention because they couple to plasmon resonances in the nanoparticles, leading to strong modulation of optical absorption and scattering. There are three mechanisms that transduce the mechanical oscillations into changes in the plasmon resonance: (1) changes in the nanoparticle geometry, (2) changes in electron density due to changes in the nanoparticle volume, and (3) changes in the interband transition energies due to compression/expansion of the nanoparticle (deformation potential). These mechanisms have been studied in the past to explain the origin of the experimental signals; however, a thorough quantitative connection between the coupling of phonon and plasmon modes has not yet been made, and the separate contribution of each coupling mechanism has not yet been quantified. Here, we present a numerical method to quantitatively determine the coupling between vibrational and plasmon modes in noble-metal nanoparticles of arbitrary geometries and apply it to silver and gold spheres, shells, rods, and cubes in the context of time-resolved measurements. We separately determine the parts of the optical response that are due to shape changes, changes in electron density, and changes in deformation potential. We further show that coupling is, in general, strongest when the regions of largest electric field (plasmon mode) and largest displacement (phonon mode) overlap. These results clarify reported experimental results and should help guide future experiments and potential applications.
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Affiliation(s)
- Aftab Ahmed
- Department of Electrical Engineering, California State University Long Beach , Long Beach, California 90840, United States
- Center for Nanoscale Materials, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Matthew Pelton
- Department of Physics, University of Maryland, Baltimore County , Baltimore, Maryland 21250, United States
- Center for Nanoscale Materials, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Jeffrey R Guest
- Center for Nanoscale Materials, Argonne National Laboratory , Argonne, Illinois 60439, United States
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10
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Pileni MP. Impact of the Metallic Crystalline Structure on the Properties of Nanocrystals and Their Mesoscopic Assemblies. Acc Chem Res 2017; 50:1946-1955. [PMID: 28726381 DOI: 10.1021/acs.accounts.7b00093] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The spontaneous assembly of uniform-sized globular entities into ordered arrays is a universal phenomenon observed for objects with diameters spanning a broad range of length scales. These extend from the atomic scale (10-8 cm), through molecular and macromolecular scales with proteins, synthetic low polymers, and colloidal crystals (∼10-6 cm), to the wavelength of visible light (∼10-5 cm). The associated concepts of sphere packing have had an influence in diverse fields ranging from pure geometrical analysis to architectural models or ideals. Self-assembly of atoms, supramolecules, or nanocrystals into ordered functional superstructures is a universal process and prevalent topic in science. About five billion years ago in the early solar system, highly uniform magnetite particles of a few hundred nanometers in size were assembled in 3D arrays.1 Thirty million years ago, silicate particles with submicrometer size were self-organized in the form of opal.2 Opal is colorless when composed of disordered silicate microparticles whereas it shows specific reflectivity when particles order in arrays. Nowadays, nanocrystals, characterized by a narrow size distribution and coated with alkyl chains to maintain their integrity, self-assemble to form crystallographic orders called supracrystals. Nanocrystals and supracrystals are arrangements of highly ordered atoms and nanocrystals, respectively. The morphologies of nanocrystals, supracrystals, and minerals are similar at various scales from nanometer to millimeter scale.3,4 Such suprastructures, which enable the design of novel materials, are expected to become one of the main driving forces in material research for the 21st century.5,6 Nanocrystals vibrate coherently in a supracrystal as atoms in a nanocrystal. Longitudinal acoustic phonons are detected in supracrystals as with atomic crystals, where longitudinal acoustic phonons propagate through coherent movements of atoms of the lattice out of their equilibrium positions. These vibrational properties show a full analogy with atomic crystals: In supracrystals, atoms are replaced by (uncompressible) nanocrystals and atomic bonds by coating agents (carbon chains), which act like mechanical springs holding together the nanocrystals. Electronic properties of very thick (more than a few micrometers) supracrystals reveal homogeneous conductance with the fingerprint of the isolated nanocrystal. Triangular single crystals formed by heat-induced (50 °C) coalescence of thin supracrystals deposited on a substrate as epitaxial growth of metal particles on a substrate with specific orientation produced by ultrahigh vacuum (UHV). Here we demonstrate that marked changes can occur in the chemical and physical properties of nanocrystals differing by their nanocrystallinity, that is, their crystalline structure. Furthermore, the properties (mechanical, growth processes) of supracrystals also change with the nanocrystallinity of the nanoparticles used as building blocks.
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11
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Wang L, Sagaguchi T, Okuhata T, Tsuboi M, Tamai N. Electron and Phonon Dynamics in Hexagonal Pd Nanosheets and Ag/Pd/Ag Sandwich Nanoplates. ACS NANO 2017; 11:1180-1188. [PMID: 28036162 DOI: 10.1021/acsnano.6b07082] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Pd and its hybrid nanostructures have attracted considerable attention over the past decade, with both catalytic and plasmonic properties. The electron and phonon properties directly govern conversion efficiencies in applications such as energy collectors and photocatalysts. We report the dynamic processes of electron-phonon coupling and coherent acoustic phonon vibration in hexagonal Pd nanosheets and Ag/Pd/Ag sandwich nanoplates using transient absorption spectroscopy. The electron-phonon coupling constant of Pd nanosheets, GPd-nanosheet (8.7 × 1017 W/(m3·K)) is larger than that of the bulk GPd (5.0 × 1017 W/(m3·K)). The effective coupling constant Geff of Ag/Pd/Ag nanoplates decreases with increasing Ag shell thickness, finally approaching the bulk GAg. The variation of Geff is explained in terms of reduced density of states near Fermi level of Pd nanosheets with 1.8 nm ultrathin thickness. Coherent acoustic phonon vibration in Pd nanosheets is assigned to a fundamental breathing mode, similar to the vibration of benzene. The period increases with increasing Ag shell thickness. For Ag/Pd/Ag nanoplates with 20 nm thick Ag shells, the vibrational mode is ascribed to a quasi-extensional mode. The results show that the modes of the coherent acoustic phonon vibration transform with the geometric variation of Pd nanosheets and Ag/Pd/Ag nanoplates. Our results represent an understanding of quantum-confinement related electron dynamics and bulk-like phonon kinetics in the ultrathin Pd nanosheets and their hybrid nanostructures.
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Affiliation(s)
- Li Wang
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University , Sanda 669-1337, Japan
| | - Takuya Sagaguchi
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University , Sanda 669-1337, Japan
| | - Tomoki Okuhata
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University , Sanda 669-1337, Japan
| | - Motohiro Tsuboi
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University , Sanda 669-1337, Japan
| | - Naoto Tamai
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University , Sanda 669-1337, Japan
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12
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Gan Y, Sun Z, Chen Z. Breathing mode vibrations and elastic properties of single-crystal and penta-twinned gold nanorods. Phys Chem Chem Phys 2016; 18:22590-8. [PMID: 27476532 DOI: 10.1039/c6cp03182j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The acoustic vibrations of individual single-crystal and penta-twinned gold nanorods with widths from ∼7 to ∼26 nm are studied using atomic-level simulations and finite element calculations. It is demonstrated that the continuum model in the limit of an infinite rod length could be used to describe the breathing periods of nanorods with an aspect ratio as small as ∼2.5, in combination with bulk material elastic constants. The elastic moduli of gold nanorods are determined via their atomistically simulated extensional periods and the dispersion relation based on long-wavelength approximation. The twinned nanorods become stiffer as the width is reduced, which is in contrast to the size dependence of the modulus in single-crystal nanorods. Further finite element calculations for the breathing periods of nanorods are performed using isotropic elastic constants of bulk gold. We find that the breathing vibrations of the penta-twinned nanorods are more affected by the crystal structure effect than those of single-crystal nanorods, because a smaller range of crystal directions perpendicular to the long axis is involved in the breathing vibrations of twinned nanorods.
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Affiliation(s)
- Yong Gan
- Faculty of Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, China.
| | - Zheng Sun
- Faculty of Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, China.
| | - Zhen Chen
- Department of Civil & Environmental Engineering, University of Missouri, Columbia, MO 65211, USA
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13
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Yu K, Major TA, Chakraborty D, Devadas MS, Sader JE, Hartland GV. Compressible Viscoelastic Liquid Effects Generated by the Breathing Modes of Isolated Metal Nanowires. NANO LETTERS 2015; 15:3964-3970. [PMID: 25978787 DOI: 10.1021/acs.nanolett.5b00853] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Transient absorption microscopy is used to examine the breathing modes of single gold nanowires in highly viscous liquids. By performing measurements on the same wire in air and liquid, the damping contribution from the liquid can be separated from the intrinsic damping of the nanowire. The results show that viscous liquids strongly reduce the vibrational lifetimes but not to the extent predicted by standard models for nanomaterial-liquid interactions. To explain these results a general theory for compressible viscoelastic fluid-structure interactions is developed. The theory results are in good agreement with experiment, which confirms that compressible non-Newtonian flow phenomena are important for vibrating nanostructures. This is the first theoretical study and experimental measurement of the compressible viscoelastic properties of simple liquids.
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Affiliation(s)
- Kuai Yu
- †Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
| | - Todd A Major
- †Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
| | - Debadi Chakraborty
- ‡School of Mathematics and Statistics, The University of Melbourne, Victoria 3010, Australia
| | - Mary Sajini Devadas
- †Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
| | - John E Sader
- ‡School of Mathematics and Statistics, The University of Melbourne, Victoria 3010, Australia
| | - Gregory V Hartland
- †Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
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14
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Goubet N, Tempra I, Yang J, Soavi G, Polli D, Cerullo G, Pileni MP. Size and nanocrystallinity controlled gold nanocrystals: synthesis, electronic and mechanical properties. NANOSCALE 2015; 7:3237-3246. [PMID: 25619359 DOI: 10.1039/c4nr06513a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The influence of nanocrystallinity on the electronic and mechanical properties of metal nanoparticles is still poorly understood, due to the difficulty in synthesizing nanoparticles with a controlled internal structure. Here, we report on a new method for the selective synthesis of Au nanoparticles in either a single-domain or a polycrystalline phase maintaining the same chemical environment. We obtain quasi-spherical nanoparticles whose diameter is tunable from 6 to 13 nm with a resolution down to ≈0.5 nm and narrow size distribution (4-5%). The availability of such high-quality samples allows the study of the impact of the particle size and nanocrystallinity on a number of parameters, such as plasmon dephasing time, electron-phonon coupling, period and damping time of the radial breathing modes.
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Affiliation(s)
- N Goubet
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8233, MONARIS, F-75005, Paris, France.
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15
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Ng MY, Ho IL, Chang YC. Crystallinity effects on scaling properties of photoinduced modes in silver nanoprisms. J Chem Phys 2015; 142:074707. [DOI: 10.1063/1.4908160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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16
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Crut A, Maioli P, Del Fatti N, Vallée F. Time-domain investigation of the acoustic vibrations of metal nanoparticles: size and encapsulation effects. ULTRASONICS 2015; 56:98-108. [PMID: 24656934 DOI: 10.1016/j.ultras.2014.02.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 02/13/2014] [Indexed: 06/03/2023]
Abstract
The acoustic vibrations of single-metal and multi-material nanoparticles are studied by ultrafast pump-probe optical spectroscopy and described in the context of the continuous elastic model. The applicability of this model to the small size range, down to one nanometer, is discussed in the light of recent experimental data and ab initio calculations. Investigations of multi-material nano-objects stress the impact of the intra-particle interface on the characteristics of their vibrational modes, also yielding information on the composition and spatial distribution of the constituting materials.
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Affiliation(s)
- Aurélien Crut
- FemtoNanoOptics Group, Institut Lumière Matière UMR5306, Université Lyon 1-CNRS, 69622 Villeurbanne, France.
| | - Paolo Maioli
- FemtoNanoOptics Group, Institut Lumière Matière UMR5306, Université Lyon 1-CNRS, 69622 Villeurbanne, France
| | - Natalia Del Fatti
- FemtoNanoOptics Group, Institut Lumière Matière UMR5306, Université Lyon 1-CNRS, 69622 Villeurbanne, France
| | - Fabrice Vallée
- FemtoNanoOptics Group, Institut Lumière Matière UMR5306, Université Lyon 1-CNRS, 69622 Villeurbanne, France
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17
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Goupalov SV. Crystal structure anisotropy explains anomalous elastic properties of nanorods. NANO LETTERS 2014; 14:1590-1595. [PMID: 24564233 DOI: 10.1021/nl404837e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
It is demonstrated that the frequency of the extensional vibrational mode of a nanorod made of an elastically anisotropic crystalline material deviates widely from the predictions of the theories based on the analysis of the long-wavelength limit. The dispersion relation for the fundamental extensional mode of a gold rod grown in the [100] direction is calculated and found to be in excellent agreement with experimental data obtained from the transient optical absorption measurements on gold nanorods. This explains an anomaly in the elastic properties of nanorods which was previously attributed to a 26% decrease in Young's modulus for nanorods compared to its bulk value. The developed approach allows one to investigate the role of the crystal structure anisotropy for acoustic phonons in nanorods and nanowires made of any metal or semiconductor material having cubic crystal structure.
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Affiliation(s)
- Serguei V Goupalov
- Department of Physics, Jackson State University , Jackson, Mississippi 39217, United States
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18
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Major TA, Lo SS, Yu K, Hartland GV. Time-Resolved Studies of the Acoustic Vibrational Modes of Metal and Semiconductor Nano-objects. J Phys Chem Lett 2014; 5:866-874. [PMID: 26274080 DOI: 10.1021/jz4027248] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Over the past decade, there have been a number of transient absorption studies of the acoustic vibrational modes of metal and semiconductor nanoparticles. This Perspective provides an overview of this work. The way that the frequencies of the observed modes depend on the size and shape of the particles is described, along with their damping. Future research directions are also discussed, especially how these measurements provide information about the way nano-objects interact with their environment.
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Affiliation(s)
- Todd A Major
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
| | - Shun Shang Lo
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
| | - Kuai Yu
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
| | - Gregory V Hartland
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
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19
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Mahmoud MA, O'Neil D, El-Sayed MA. Shape- and symmetry-dependent mechanical properties of metallic gold and silver on the nanoscale. NANO LETTERS 2014; 14:743-748. [PMID: 24328338 DOI: 10.1021/nl4040362] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The mechanical properties of anisotropic nanoparticles like gold nanorods (AuNRs) and silver nanorods (AgNRs) are different from those of isotropic shapes such as nanospheres. We probed the coherent lattice oscillations of nanoparticles by following the modulation of the plasmonic band frequency using ultrafast laser spectroscopy. We found that while the frequency of the longitudinal vibration mode of AgNRs is higher than that of AuNRs of similar dimensions, similarly sized gold and silver nanospheres have similar lattice vibration frequencies. Lattice vibrations calculated by finite element modeling showed good agreement with the experimental results for both AgNRs and AuNRs. The accuracy of the calculations was improved by using actual pentagonal shapes rather than cylinders that did not agree well with the experimental results. As the plasmon energy is transferred into lattice vibrations, the temperature of the nanoparticle necessarily increases as a result of this electron-phonon relaxation process. This results in a decrease in the Young's modulus that was accounted for in the calculations. Calculations showed that the tips of the nanorods are "softer" than the rest of the nanorod. Because the tips comprise a larger portion of the overall rod in the smaller rods, the smaller rods were more affected by the tip effects.
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Affiliation(s)
- Mahmoud A Mahmoud
- Laser Dynamics Laboratory, School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
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20
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Crut A, Maioli P, Del Fatti N, Vallée F. Optical absorption and scattering spectroscopies of single nano-objects. Chem Soc Rev 2014; 43:3921-56. [DOI: 10.1039/c3cs60367a] [Citation(s) in RCA: 147] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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21
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Abstract
Ultrafast x-ray diffraction studies reveal the lattice vibrations of single gold nanoparticles.
[Also see Report by
Clark
et al.
]
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Affiliation(s)
- Gregory V Hartland
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46557-5670, USA.
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22
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Yang Z, Lisiecki I, Walls M, Pileni MP. Nanocrystallinity and the ordering of nanoparticles in two-dimensional superlattices: controlled formation of either core/shell (Co/CoO) or hollow CoO nanocrystals. ACS NANO 2013; 7:1342-1350. [PMID: 23312113 DOI: 10.1021/nn304922s] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Here it is demonstrated that the diffusion process of oxygen in Co nanoparticles is controlled by their 2D ordering and crystallinity. The crystallinity of isolated Co nanoparticles deposited on a substrate does not play any role in the oxide formation. When they are self-assembled in 2D superlattices, the oxidation process is slowed and produces either core/shell (Co/CoO) nanoparticles or hollow CoO nanocrystals. This is attributed to the decrease in the oxygen diffusion rate when the nanoparticles are interdigitated. Initially, polycrystalline nanoparticles form core/shell (Co/CoO) structures, while for single-domain hexagonal close-packed Co nanocrystals, the outward diffusion of Co ions is favored over the inward diffusion of oxygen, producing hollow CoO single-domain nanocrystals.
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Affiliation(s)
- Zhijie Yang
- Laboratoire des Matériaux Mésoscopiques et Nanométriques, UMR CNRS 7070, Université P. et M. Curie Bât F, 4 Place Jussieu, 75005 Paris, France
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23
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Goubet N, Yan C, Polli D, Portalès H, Arfaoui I, Cerullo G, Pileni MP. Modulating physical properties of isolated and self-assembled nanocrystals through change in nanocrystallinity. NANO LETTERS 2013; 13:504-8. [PMID: 23272764 DOI: 10.1021/nl303898y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
For self-assembled nanocrystals in three-dimensional (3D) superlattices, called supracrystals, the crystalline structure of the metal nanocrystals (either single domain or polycrystalline) or nanocrystallinity is likely to induce significant changes in the physical properties. Previous studies demonstrated that spontaneous nanocrystallinity segregation takes place in colloidal solution upon self-assembling of 5 nm dodecanethiol-passivated Au nanocrystals. This segregation allows the exclusive selection of single domain and polycrystalline nanoparticles and consequently producing supracrystals with these building blocks. Here, we investigate the influence of nanocrystallinity on different properties of nanocrystals with either single domain or polycrystalline structure. In particular, the influence of nanocrystallinity on the localized surface plasmon resonance of individual nanocrystals dispersed in the same dielectric media is reported. Moreover, the frequencies of the radial breathing mode of single domain and polycrystalline nanoparticles are measured. Finally, the orientational ordering of single domain nanocrystals markedly changes the supracrystal elastic moduli compared to supracrystals of polycrystalline nanocrystals.
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Affiliation(s)
- Nicolas Goubet
- Université Pierre et Marie Curie, UMR 7070, LM2N, 4 place Jussieu 75005 Paris, France
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24
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Major TA, Crut A, Gao B, Lo SS, Fatti ND, Vallée F, Hartland GV. Damping of the acoustic vibrations of a suspended gold nanowire in air and water environments. Phys Chem Chem Phys 2013. [DOI: 10.1039/c2cp43330c] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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25
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Pileni MP. Supra- and nanocrystallinity: specific properties related to crystal growth mechanisms and nanocrystallinity. Acc Chem Res 2012; 45:1965-72. [PMID: 23003577 DOI: 10.1021/ar3000597] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The natural arrangement of atoms or nanocrystals either in well-defined assemblies or in a disordered fashion induces changes in their physical properties. For example, diamond and graphite show marked differences in their physical properties though both are composed of carbon atoms. Natural colloidal crystals have existed on earth for billions of years. Very interestingly, these colloidal crystals are made of a fixed number of polyhedral magnetite particles uniform in size. Hence, opals formed of assemblies of silicate particles in the micrometer size range exhibit interesting intrinsic optical properties. A colorless opal is composed of disordered particles, but changes in size segregation within the self-ordered silica particles can lead to distinct color changes and patterning. In this Account, we rationalize two simultaneous supracrystal growth processes that occur under saturated conditions, which form both well-defined 3D superlattices at the air-liquid interface and precipitated 3D assemblies with well-defined shapes. The growth processes of these colloidal crystals, called super- or supracrystals, markedly change the mechanical properties of these assemblies and induce the crystallinity segregation of nanocrystals. Therefore, single domain nanocrystals are the primary basis in the formation of these supracrystals, while multiply twinned particles (MTPs) and polycrystals remain dispersed within the colloidal suspension. Nanoindentation measurements show a drop in the Young's moduli for interfacial supracrystals in comparison with the precipitated supracrystals. In addition, the value of the Young's modulus changes markedly with the supracrystal growth mechanism. Using scanning tunneling microscopy/spectroscopy, we successfully imaged very thick supracrystals (from 200 nm up to a few micrometers) with remarkable conductance homogeneity and showed electronic fingerprints of isolated nanocrystals. This discovery of nanocrystal fingerprints within supracrystals could lead to promising applications in nanotechnology.
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Affiliation(s)
- M. P. Pileni
- Laboratoire des Matériaux Mesoscopiques et Nanométriques (LM2N), UMR CNRS 7070, Université Pierre et Marie Curie, bât F, BP 52, 4 place Jussieu, 75252 Paris Cedex 05, France
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26
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Cardinal MF, Mongin D, Crut A, Maioli P, Rodríguez-González B, Pérez-Juste J, Liz-Marzán LM, Del Fatti N, Vallée F. Acoustic Vibrations in Bimetallic Au@Pd Core-Shell Nanorods. J Phys Chem Lett 2012; 3:613-619. [PMID: 26286157 DOI: 10.1021/jz3000992] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The acoustic vibrations of gold nanorods coated with palladium were investigated as a function of Pd amount using ultrafast pump-probe spectroscopy. Both the extensional and breathing vibrational modes of the nanorods were coherently excited and detected. This permits precise determination of their periods, which were found to decrease and increase with Pd deposition, for the extensional and vibrational modes, respectively. These opposite behaviors reflect changes of the nanoparticle size and mechanical properties, in agreement with numerical simulations. Comparison of experimental and computed periods yields information on the amount of deposited Pd, providing a novel tool to characterize bicomponent nano-objects for small fractions of one of the components (Pd/Au atomic fraction down to 5%).
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Affiliation(s)
- M Fernanda Cardinal
- †Departamento de Quimica Fisica, Universidade de Vigo, 36310 Vigo, Spain
- ‡International Iberian Nanotechnology Laboratory, Braga, 4710229, Portugal
| | - Denis Mongin
- §FemtoNanoOptics Group, Université Lyon 1, CNRS, LASIM, 43 Bd du 11 Novembre, 69622 Villeurbanne, France
| | - Aurélien Crut
- §FemtoNanoOptics Group, Université Lyon 1, CNRS, LASIM, 43 Bd du 11 Novembre, 69622 Villeurbanne, France
| | - Paolo Maioli
- §FemtoNanoOptics Group, Université Lyon 1, CNRS, LASIM, 43 Bd du 11 Novembre, 69622 Villeurbanne, France
| | | | - Jorge Pérez-Juste
- †Departamento de Quimica Fisica, Universidade de Vigo, 36310 Vigo, Spain
| | - Luis M Liz-Marzán
- †Departamento de Quimica Fisica, Universidade de Vigo, 36310 Vigo, Spain
| | - Natalia Del Fatti
- §FemtoNanoOptics Group, Université Lyon 1, CNRS, LASIM, 43 Bd du 11 Novembre, 69622 Villeurbanne, France
| | - Fabrice Vallée
- §FemtoNanoOptics Group, Université Lyon 1, CNRS, LASIM, 43 Bd du 11 Novembre, 69622 Villeurbanne, France
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27
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Polli D, Lisiecki I, Portalès H, Cerullo G, Pileni MP. Low sensitivity of acoustic breathing mode frequency in Co nanocrystals upon change in nanocrystallinity. ACS NANO 2011; 5:5785-5791. [PMID: 21671570 DOI: 10.1021/nn201468h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Cobalt nanocrystals (NCs) with narrow size distribution and polycrystalline structure in their native form are synthesized in reverse micelles. After annealing at 350 °C, these NCs are transformed into single crystalline phase with hexagonal close-packed structure. The vibrational dynamics of NCs differing by their nanocrystallinity is studied by femtosecond pump-probe spectroscopy. By recording the differential reflectivity signal in the native and annealed Co NCs, the frequency of their fundamental breathing acoustic mode can be measured in the time domain. A small decrease of the breathing mode frequency is observed in single crystalline Co NCs compared to that measured in polycrystals, indicating low sensitivity of their fundamental radial mode upon change in crystallinity. This result is in agreement with predictions from calculations using the resonant ultrasound approach.
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Affiliation(s)
- Dario Polli
- IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, P.za L. da Vinci 32, 20133 Milano, Italy
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28
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Mongin D, Juvé V, Maioli P, Crut A, Del Fatti N, Vallée F, Sánchez-Iglesias A, Pastoriza-Santos I, Liz-Marzán LM. Acoustic vibrations of metal-dielectric core-shell nanoparticles. NANO LETTERS 2011; 11:3016-3021. [PMID: 21688851 DOI: 10.1021/nl201672k] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The acoustic vibrations of metal nanoparticles encapsulated in a dielectric shell (Ag@SiO(2)) were investigated using a time-resolved femtosecond technique. The measured vibration periods significantly differ from those predicted for the bare metal cores and, depending on the relative core and shell sizes, were found to be either larger or smaller than them. These results show that the vibration of the whole core-shell particle is excited and detected. Moreover, vibrational periods are in excellent agreement with the predictions of a model based on continuum thermoelasticity. However, such agreement is obtained only if a good mechanical contact of the metal and dielectric parts of the core-shell particle is assumed, providing a unique way to probe this contact in multimaterial or hybrid nano-objects.
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Affiliation(s)
- Denis Mongin
- FemtoNanoOptics group, LASIM, Université Lyon 1-CNRS, 43 Bd du 11 Novembre, 69622 Villeurbanne, France
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29
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Tai PT, Yu P, Tang J. Photoinduced multimode coherent acoustic phonons of metallic nanoprisms and the effects of shape-induced anisotropic electronic stresses. J Chem Phys 2011; 134:184506. [PMID: 21568520 DOI: 10.1063/1.3590373] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this work we reported experimental measurements of ultrafast structural dynamics in metallic nanoprisms induced by a femtosecond laser pulse. The main focus of this study of anisotropic heating in nanoprisms is about laser fluence effects on photoexcitation of two planar coherent acoustic phonon modes, namely, the breathing mode and the totally symmetric mode. We presented a combined two-temperature model and 2-D Fermi-Pasta-Ulam model to explain both the dependence of the initial phases and the mode weight on the excitation power. Our transient optical absorption data for both the initial fast monotonic decay and the subsequent coherent acoustic oscillations clearly indicate the presence of anisotropic thermal expansion in nanoprisms.
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Affiliation(s)
- Po-Tse Tai
- Research Center for Applied Sciences Academia Sinica, Taipei, Taiwan
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30
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Affiliation(s)
- Gregory V. Hartland
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, United States
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31
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Portalès H, Goubet N, Saviot L, Yang P, Sirotkin S, Duval E, Mermet A, Pileni MP. Crystallinity dependence of the plasmon resonant Raman scattering by anisotropic gold nanocrystals. ACS NANO 2010; 4:3489-3497. [PMID: 20565142 DOI: 10.1021/nn1005446] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Au nanocrystals (NCs) with different crystalline structures and related morphologies are unselectively synthesized using an organometallic route. The acoustic vibrations of these NCs are studied by plasmon mediated low-frequency Raman scattering (LFRS). A splitting of the quadrupolar vibration mode is pointed out in the LFRS spectrum. Comparison of the measured frequencies with calculations and careful examination of the NCs morphologies by transmission electron microscopy ascertain this splitting as being an effect of crystallinity. The excitation dependence of the LFRS spectra is interpreted by the shape-selection of the NCs via plasmon-vibration coupling. These results give new insights into the crystallinity influence on both the vibrations of the NCs and their coupling with plasmons and demonstrate the relevance of elastic anisotropy in monodomain NCs.
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Affiliation(s)
- Hervé Portalès
- Universite Pierre et Marie Curie Paris 6, UMR 7070, LM2N, 4 place Jussieu, 75005 Paris, France.
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32
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Juvé V, Crut A, Maioli P, Pellarin M, Broyer M, Del Fatti N, Vallée F. Probing elasticity at the nanoscale: Terahertz acoustic vibration of small metal nanoparticles. NANO LETTERS 2010; 10:1853-1858. [PMID: 20411965 DOI: 10.1021/nl100604r] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The acoustic response of surface-controlled metal (Pt) nanoparticles is investigated in the small size range, between 1.3 and 3 nm (i.e., 75-950 atoms), using time-resolved spectroscopy. Acoustic vibration of the nanoparticles is demonstrated, with frequencies ranging from 1.1 to 2.6 THz, opening the way to the development of THz acoustic resonators. The frequencies, measured with a noncontact optical method, are in excellent agreement with the prediction of a macroscopic approach based on the continuous elastic model, together with the bulk material elastic constants. This demonstrates the validity of this model at the nanoscale and the weak impact of size reduction on the elastic properties of a material, even for nanoparticles formed by less than 100 atoms.
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Affiliation(s)
- Vincent Juvé
- Université Lyon 1, CNRS, LASIM, 43 bd du 11 Novembre 1918, Villeurbanne cedex, France
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33
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Gebs R, Klatt G, Janke C, Dekorsy T, Bartels A. High-speed asynchronous optical sampling with sub-50fs time resolution. OPTICS EXPRESS 2010; 18:5974-5983. [PMID: 20389617 DOI: 10.1364/oe.18.005974] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report an ultrafast time-domain spectroscopy system based on high-speed asynchronous optical sampling operating without mechanical scanner. The system uses two 1 GHz femtosecond oscillators that are offset-stabilized using high-bandwidth feedback electronics operating at the tenth repetition rate harmonics. Definition of the offset frequency, i.e. the time-delay scan rate, in the range of a few kilohertz is accomplished using direct-digital-synthesis electronics for the first time. The time-resolution of the system over the full available 1 ns time-delay window is determined by the laser pulse duration and is 45 fs. This represents a three-fold improvement compared to previous approaches where timing jitter was the limiting factor. Two showcase experiments are presented to verify the high time-resolution and sensitivity of the system.
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Affiliation(s)
- R Gebs
- Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457, Germany.
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