Publications
120 results found
Besteiro LV, Cortes E, Ishii S, et al., 2021, Hot electron physics and applications, JOURNAL OF APPLIED PHYSICS, Vol: 129, ISSN: 0021-8979
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- Citations: 3
Li H, Liu K, Fu J, et al., 2021, Paired Ru-O-Mo ensemble for efficient and stable alkaline hydrogen evolution reaction, NANO ENERGY, Vol: 82, ISSN: 2211-2855
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- Citations: 71
Barella M, Violi IL, Gargiulo J, et al., 2021, In situ photothermal response of single gold nanoparticles through hyperspectral imaging anti-stokes thermometry, ACS Nano, Vol: 15, Pages: 2458-2467, ISSN: 1936-0851
Several fields of applications require a reliable characterization of the photothermal response and heat dissipation of nanoscopic systems, which remains a challenging task for both modeling and experimental measurements. Here, we present an implementation of anti-Stokes thermometry that enables the in situ photothermal characterization of individual nanoparticles (NPs) from a single hyperspectral photoluminescence confocal image. The method is label-free, potentially applicable to any NP with detectable anti-Stokes emission, and does not require any prior information about the NP itself or the surrounding media. With it, we first studied the photothermal response of spherical gold NPs of different sizes on glass substrates, immersed in water, and found that heat dissipation is mainly dominated by the water for NPs larger than 50 nm. Then, the role of the substrate was studied by comparing the photothermal response of 80 nm gold NPs on glass with sapphire and graphene, two materials with high thermal conductivity. For a given irradiance level, the NPs reach temperatures 18% lower on sapphire and 24% higher on graphene than on bare glass. The fact that the presence of a highly conductive material such as graphene leads to a poorer thermal dissipation demonstrates that interfacial thermal resistances play a very significant role in nanoscopic systems and emphasize the need for in situ experimental thermometry techniques. The developed method will allow addressing several open questions about the role of temperature in plasmon-assisted applications, especially ones where NPs of arbitrary shapes are present in complex matrixes and environments.
Lee JB, Walker H, Li Y, et al., 2020, Template dissolution interfacial patterning of single colloids for nanoelectrochemistry and nanosensing, ACS Nano, Vol: 14, Pages: 17693-17703, ISSN: 1936-0851
Deterministic positioning and assembly of colloidal nanoparticles (NPs) onto substrates is a core requirement and a promising alternative to top-down lithography to create functional nanostructures and nanodevices with intriguing optical, electrical, and catalytic features. Capillary-assisted particle assembly (CAPA) has emerged as an attractive technique to this end, as it allows controlled and selective assembly of a wide variety of NPs onto predefined topographical templates using capillary forces. One critical issue with CAPA, however, lies in its final printing step, where high printing yields are possible only with the use of an adhesive polymer film. To address this problem, we have developed a template dissolution interfacial patterning (TDIP) technique to assemble and print single colloidal AuNP arrays onto various dielectric and conductive substrates in the absence of any adhesion layer, with printing yields higher than 98%. The TDIP approach grants direct access to the interface between the AuNP and the target surface, enabling the use of colloidal AuNPs as building blocks for practical applications. The versatile applicability of TDIP is demonstrated by the creation of direct electrical junctions for electro- and photoelectrochemistry and nanoparticle-on-mirror geometries for single-particle molecular sensing.
Cortes E, Besteiro L, Alabastri A, et al., 2020, Challenges in Plasmonic Catalysis, ACS NANO, Vol: 14, Pages: 16202-16219, ISSN: 1936-0851
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- Citations: 164
Lee S, Hwang H, Lee W, et al., 2020, Core-Shell Bimetallic Nanoparticle Trimers for Efficient Light-to-Chemical Energy Conversion, ACS ENERGY LETTERS, Vol: 5, Pages: 3881-3890, ISSN: 2380-8195
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- Citations: 29
Tilmann B, Grinblat G, Berte R, et al., 2020, Nanostructured amorphous gallium phosphide on silica for nonlinear and ultrafast nanophotonics, NANOSCALE HORIZONS, Vol: 5, Pages: 1500-1508, ISSN: 2055-6756
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- Citations: 15
Poblet M, Li Y, Cortes E, et al., 2020, Direct Detection of Optical Forces of Magnetic Nature in Dielectric Nanoantennas, NANO LETTERS, Vol: 20, Pages: 7627-7634, ISSN: 1530-6984
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- Citations: 8
Grinblat G, Zhang H, Nielsen MP, et al., 2020, Efficient ultrafast all-optical modulation in a nonlinear crystalline gallium phosphide nanodisk at the anapole excitation, Science Advances, Vol: 6, ISSN: 2375-2548
High–refractive index nanostructured dielectrics have the ability to locally enhance electromagnetic fields with low losses while presenting high third-order nonlinearities. In this work, we exploit these characteristics to achieve efficient ultrafast all-optical modulation in a crystalline gallium phosphide (GaP) nanoantenna through the optical Kerr effect (OKE) and two-photon absorption (TPA) in the visible/near-infrared range. We show that an individual GaP nanodisk can yield differential reflectivity modulations of up to ~40%, with characteristic modulation times between 14 and 66 fs, when probed at the anapole excitation (AE). Numerical simulations reveal that the AE represents a unique condition where both the OKE and TPA contribute with the same modulation sign, maximizing the response. These findings highly outperform previous reports on sub–100-fs all-optical switching from resonant nanoscale dielectrics, which have demonstrated modulation depths no larger than 0.5%, placing GaP nanoantennas as a promising choice for ultrafast all-optical modulation at the nanometer scale.
Mancini A, Gubbin CR, Berte R, et al., 2020, Near-Field Spectroscopy of Cylindrical Phonon-Polariton Antennas, ACS NANO, Vol: 14, Pages: 8508-8517, ISSN: 1936-0851
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- Citations: 10
Cortes E, Govorov AO, Misawa H, et al., 2020, Special topic on emerging directions in plasmonics, JOURNAL OF CHEMICAL PHYSICS, Vol: 153, ISSN: 0021-9606
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- Citations: 7
Boggiano HD, Berte R, Scarpettini AF, et al., 2020, Determination of nanoscale mechanical properties of polymers via plasmonic nanoantennas, ACS Photonics, Vol: 7, Pages: 1403-1409, ISSN: 2330-4022
Nanotechnology and the consequent emergence of miniaturized devices are driving the need to improve our understanding of the mechanical properties of a myriad of materials. Here we focus on amorphous polymeric materials and introduce a new way to determine the nanoscale mechanical response of polymeric thin films in the GHz range, using ultrafast optical means. Coupling of the films to plasmonic nanoantennas excited at their vibrational eigenfrequencies allows the extraction of the values of the mechanical moduli as well as the estimation of the glass transition temperature via time-domain measurements, here demonstrated for PMMA films. This nanoscale method can be extended to the determination of mechanical and elastic properties of a wide range of spatially strongly confined materials.
Bell SEJ, Charron G, Cortes E, et al., 2020, Towards Reliable and Quantitative Surface-Enhanced Raman Scattering (SERS): From Key Parameters to Good Analytical Practice, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, Vol: 59, Pages: 5454-5462, ISSN: 1433-7851
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- Citations: 11
Bell SEJ, Charron G, Cortés E, et al., 2020, Auf dem Weg zur verlässlichen und quantitativen SERS‐Spektroskopie: von Schlüsselparametern zur guten analytischen Praxis, Angewandte Chemie, Vol: 132, Pages: 5496-5505, ISSN: 0044-8249
<jats:title>Abstract</jats:title><jats:p>Experimentelle Resultate, die in verschiedenen Laboren weltweit von Wissenschaftlern mithilfe der oberflächenverstärkten Raman‐Streuung (SERS, surface‐enhanced Raman scattering) erhalten wurden, können beträchtlich voneinander abweichen. Wir, ein internationales Team von Wissenschaftlerinnen und Wissenschaftlern mit langjähriger SERS‐Expertise, präsentieren hier unsere Sichtweise auf dieses Thema mit Betrachtungen hinsichtlich verlässlichem und quantitativem SERS. Die zentrale Idee dieses Gemeinschaftsunterfangens ist es, auf die oft in der Literatur anzutreffenden Schlüsselparameter und Stolperfallen hinzuweisen. Im Hinblick darauf bieten wir Empfehlungen zu folgenden Themen an: a) die Charakterisierung von festen und kolloidalen SERS‐Substraten durch korrelative Elektronen‐ und optische Mikroskopie und Spektroskopie, b) zur Bestimmung des SERS‐Verstärkungsfaktors (EF, enhancement factor) inklusive geeigneter Raman‐Reporter/Sonden‐Moleküle und schließlich c) zur guten analytischen Praxis. Die Autorinnen und Autoren hoffen, dass sowohl Newcomer als auch Spezialisten von diesen Empfehlungen profitieren, um die Inter‐Labor‐Vergleichbarkeit von experimentellen SERS‐Resultaten zu erhöhen und zur weiteren Etablierung von SERS als einer analytischen Methode beizutragen.</jats:p>
Morozov S, Pensa EL, Khan AH, et al., 2020, Electrical control of single-photon emission in highly-charged individual colloidal quantum dots, Publisher: arXiv
Electron transfer to an individual quantum dot promotes the formation ofcharged excitons with enhanced recombination pathways and reduced lifetimes.Excitons with only one or two extra charges have allowed for the development ofvery efficient quantum dot lasing [1] and the understanding of blinkingdynamics [2], while charge transfer management has yielded single quantum dotLEDs [3], LEDs with reduced efficiency roll-off [4], and enabled studies ofcarrier and spin dynamics [5]. Here, by room-temperature time-resolvedexperiments on individual giant-shell CdSe/CdS quantum dots, we show theelectrochemical formation of highly charged excitons containing more thantwelve electrons and one hole. We report control of intensity blinking, as wellas a deterministic manipulation of quantum dot photodynamics, with an observed210-fold increase of the decay rate, accompanied by 12-fold decrease of theemission intensity, all while preserving single-photon emissioncharacteristics. These results pave the way for deterministic control over thecharge state, and room-temperature decay-rate engineering for colloidal quantumdot-based classical and quantum communication technologies.
Hüttenhofer L, Eckmann F, Lauri A, et al., 2020, Anapole excitations in oxygen vacancy-rich TiO2-x nanoresonators: tuning the absorption for photocatalysis in the visible., ACS Nano, Vol: 14, Pages: 2456-2464, ISSN: 1936-0851
Research on optically resonant dielectric nanostructures has accelerated the development of photonic applications, driven by their ability to strongly confine light on the nanoscale. However, since dielectric resonators are typically operated below their bandgap to minimize optical losses, the usage of dielectric nanoantenna concepts for absorption enhancement has largely remained unexplored. In this work, we realize engineered nanoantennas composed of photocatalytic dielectrics and demonstrate their increased light harvesting capabilities in otherwise weakly absorptive spectral regions. In particular, we employ anapole excitations, which are known for their strong light confinement, in nanodisks of oxygen-vacancy-rich TiO2-x, a prominent photocatalyst that provides a powerful platform for exploring concepts in absorption enhancement in tunable nanostructures. We show that by varying the nanodisk geometry, we can shift the anapole wavelength into resonance with optical transitions associated with the sub-bandgap oxygen vacancy (VO) states and thereby increase visible light absorption. The arising photocatalytic effect is monitored on the single particle level using the well-established photocatalytic silver reduction reaction on TiO2. With the freedom of changing the optical properties of TiO2 through tuning the abundance of VO-states we discuss the interplay between cavity damping and the anapole-assisted field confinement for absorption enhancement. This concept is general and can be extended to other catalytic materials with higher refractive indices.
Glass D, Cortes E, Ben-Jaber S, et al., 2019, Dynamics of Photo-Induced Surface Oxygen Vacancies in Metal-Oxide Semiconductors Studied Under Ambient Conditions, ADVANCED SCIENCE, Vol: 6
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- Citations: 64
Lee S, Kim J, Yang H, et al., 2019, Particle-in-a-frame nanostructures with interior nanogaps, Angewandte Chemie International Edition, Vol: 58, Pages: 15890-15894, ISSN: 1433-7851
Designing plasmonic hollow colloids with small interior nanogaps would allow structural properties to be exploited that are normally linked to an ensemble of particles but within a single nanoparticle. Now, a synthetic approach for constructing a new class of frame nanostructures is presented. Fine control over the galvanic replacement reaction of Ag nanoprisms with Au precursors gave unprecedented Au particle-in-a-frame nanostructures with well-defined sub-2 nm interior nanogaps. The prepared nanostructures exhibited superior performance in applications, such as plasmonic sensing and surface-enhanced Raman scattering, over their solid nanostructure and nanoframe counterparts. This highlights the benefit of their interior hot spots, which can highly promote and maximize the electric field confinement within a single nanostructure.
Gargiulo J, Berte R, Li Y, et al., 2019, From optical to chemical hot spots in plasmonics, Accounts of Chemical Research, Vol: 52, Pages: 2525-2535, ISSN: 0001-4842
In recent years, the possibility to induce chemical transformations by using tunable plasmonic modes has opened the question of whether we can control or create chemical hot spots in these systems. This can be rationalized as the reactive analogue of the well-established concept of optical hot spots, which have drawn a great deal of attention to plasmonic nanostructures for their ability to circumvent the far-field diffraction limit of conventional optical elements.Although optical hot spots can be mainly defined by the geometry and permittivity of the nanostructures, the degrees of freedom influencing their photocatalytic properties appear to be much more numerous. In fact, the reactivity of plasmonic systems are deeply influenced by the dynamics and interplay of photons, plasmon-polaritons, carriers, phonons, and molecular states. These degrees of freedom can affect the reaction rates, the product selectivity, or the spatial localization of a chemical reaction. In this Account, we discuss the oportunities to control chemical hot spots by tuning the cascade of events that follows the excitation and decay of plasmonic modes in nanostructures.We discuss a series of techniques to spatially map and image plasmonic nanoscale reactivity at the single photocatalyst level. We show how to optimize the reactivity of carriers by manipulating their excitation and decay mechanisms in plasmonic nanoparticles. In addition, the tailored generation of non-thermal phonons in metallic nanostructures and their dissipation is shown as a promise to understand and exploit thermal photocatalysis at the nanoscale. Understanding and controlling these processes is essential for the rational design of solar nanometric photocatalysts.Nevertheless, the ultimate capability of a plasmonic photocatalyst to trigger a chemical reaction is correlated to its ability to navigate through, or even modify, the potential energy surface of a given chemical reaction. Here we reunite both worlds, the plasmoni
Guerra Hernandez LA, Huidobro PA, Cortes E, et al., 2019, Resonant Far- to Near-Field Channeling in Synergetic Multiscale Antennas, ACS PHOTONICS, Vol: 6, Pages: 1466-1473, ISSN: 2330-4022
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- Citations: 4
Simoncelli S, Pensa EL, Brick T, et al., 2019, Monitoring plasmonic hot-carrier chemical reactions at the single particle level, Faraday Discussions, Vol: 214, Pages: 73-87, ISSN: 1359-6640
Plasmon excitation in metal nanoparticles triggers the generation of highly energetic charge carriers that, when properly manipulated and exploited, can mediate chemical reactions. Single-particle techniques are key to unearthing the underlying mechanisms of hot-carrier generation, transport and injection, as well as to disentangling the role of the temperature increase and the enhanced near-field at the nanoparticle-molecule interface. Gaining nanoscopic insight into these processes and their interplay could aid in the rational design of plasmonic photocatalysts. Here, we present three different approaches to monitor hot-carrier reactivity at the single-particle level. We use a combination of dark-field microscopy and photoelectrochemistry to track a hot-hole driven reaction on a single Au nanoparticle. We image hot-electron reactivity with sub-particle spatial resolution using nanoscopy techniques. Finally, we push the limits by looking for a hot-electron induced chemical reaction that generates a fluorescent product, which should enable imaging plasmonic photocatalysis at the single-particle and single-molecule levels.
Aizpurua J, Ashfold M, Baletto F, et al., 2019, Dynamics of hot electron generation in metallic nanostructures: general discussion., Faraday Discuss, Vol: 214, Pages: 123-146
Zaza C, Violi IL, Gargiulo J, et al., 2019, Size-selective optical printing of silicon nanoparticles through their dipolar magnetic resonance, ACS Photonics, Vol: 6, Pages: 815-822, ISSN: 2330-4022
Silicon nanoparticles possess unique size-dependent optical properties due to their strong electric and magnetic resonances in the visible range. However, their widespread application has been limited, in comparison with other (e.g., metallic) nanoparticles, because their preparation on monodisperse colloids remains challenging. Exploiting the unique properties of Si nanoparticles in nano- A nd microdevices calls for methods able to sort and organize them from a colloidal suspension onto specific positions of solid substrates with nanometric precision. We demonstrate that surfactant-free silicon nanoparticles of a predefined and narrow (σ < 10 nm) size range can be selectively immobilized on a substrate by optical printing from a polydisperse colloidal suspension. The size selectivity is based on differential optical forces that can be applied on nanoparticles of different sizes by tuning the light wavelength to the size-dependent magnetic dipolar resonance of the nanoparticles.
Pensa E, Gargiulo J, Lauri A, et al., 2019, Spectral screening of the energy of hot holes over a particle plasmon resonance, Nano Letters, Vol: 19, Pages: 1867-1874, ISSN: 1530-6984
Plasmonic hot carriers have been recently identified as key elements for photocatalysis at visible wavelengths. The possibility to transfer energy between metal plasmonic nanoparticles and nearby molecules depends not only on carrier generation and collection efficiencies but also on their energy at the metal-molecule interface. Here an energy screening study was performed by monitoring the aniline electro-polymerization reaction via an illuminated 80 nm gold nanoparticle. Our results show that plasmon excitation reduces the energy required to start the polymerization reaction as much as 0.24 eV. Three possible photocatalytic mechanisms were explored: the enhanced near field of the illuminated particle, the temperature increase at the metal-liquid interface, and the excited electron-hole pairs. This last phenomenon is found to be the one contributing most prominently to the observed energy reduction.
Berte R, Della Picca F, Poblet M, et al., 2018, Acoustic far-field hypersonic surface wave detection with single plasmonic nanoantennas, Physical Review Letters, Vol: 121, ISSN: 0031-9007
The optical properties of small metallic particles allow us to bridge the gap between the myriad of subdiffraction local phenomena and macroscopic optical elements. The optomechanical coupling between mechanical vibrations of Au nanoparticles and their optical response due to collective electronic oscillations leads to the emission and the detection of surface acoustic waves (SAWs) by single metallic nanoantennas. We take two Au nanoparticles, one acting as a source and the other as a receptor of SAWs and, even though these antennas are separated by distances orders of magnitude larger than the characteristic subnanometric displacements of vibrations, we probe the frequency content, wave speed, and amplitude decay of SAWs originating from the damping of coherent mechanical modes of the source. Two-color pump-probe experiments and numerical methods reveal the characteristic Rayleigh wave behavior of emitted SAWs, and show that the SAW-induced optical modulation of the receptor antenna allows us to accurately probe the frequency of the source, even when the eigenmodes of source and receptor are detuned.
Cortes E, 2018, Activating plasmonic chemistry, SCIENCE, Vol: 362, Pages: 28-29, ISSN: 0036-8075
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- Citations: 66
Simoncelli S, Li Y, Cortés E, et al., 2018, Imaging plasmon hybridization of fano resonances via hot-electron-mediated absorption mapping, Nano Letters, Vol: 18, Pages: 3400-3406, ISSN: 1530-6984
The inhibition of radiative losses in dark plasmon modes allows storing electromagnetic energy more efficiently than in far-field excitable bright-plasmon modes. As such, processes benefiting from the enhanced absorption of light in plasmonic materials could also take profit of dark plasmon modes to boost and control nanoscale energy collection, storage, and transfer. We experimentally probe this process by imaging with nanoscale precision the hot-electron driven desorption of thiolated molecules from the surface of gold Fano nanostructures, investigating the effect of wavelength and polarization of the incident light. Spatially resolved absorption maps allow us to show the contribution of each element of the nanoantenna in the hot-electron driven process and their interplay in exciting a dark plasmon mode. Plasmon-mode engineering allows control of nanoscale reactivity and offers a route to further enhance and manipulate hot-electron driven chemical reactions and energy-conversion and transfer at the nanoscale.
Cambiasso J, Koenig M, Cortes E, et al., 2018, Surface-Enhanced Spectroscopies of a Molecular Monolayer in an All-Dielectric Nanoantenna, ACS PHOTONICS, Vol: 5, Pages: 1546-1557, ISSN: 2330-4022
Torrelles X, Pensa E, Cortes E, et al., 2018, Solving the Long-Standing Controversy of Long-Chain Alkanethiols Surface Structure on Au(111), JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 122, Pages: 3893-3902, ISSN: 1932-7447
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- Citations: 13
Simoncelli S, Li Y, Cortés E, et al., 2018, Nanoscale control of molecular self-assembly induced by plasmonic hot-electron dynamics, ACS Nano, Vol: 12, Pages: 2184-2192, ISSN: 1936-0851
Self-assembly processes allow designing and creating complex nanostructures using molecules as building blocks and surfaces as scaffolds. This autonomous driven construction is possible due to a complex thermodynamic balance of molecule-surface interactions. As such, nanoscale guidance and control over this process is hard to achieve. Here we use the highly localized light-to-chemical-energy conversion of plasmonic materials to spatially cleave Au-S bonds on predetermined locations within a single nanoparticle, enabling a high degree of control over this archetypal system for molecular self-assembly. Our method offers nanoscale precision and high-throughput light-induced tailoring of the surface chemistry of individual and packed nanosized metallic structures by simply varying wavelength and polarization of the incident light. Assisted by single-molecule super-resolution fluorescence microscopy, we image, quantify, and shed light onto the plasmon-induced desorption mechanism. Our results point toward localized distribution of hot electrons, contrary to uniformly distributed lattice heating, as the mechanism inducing Au-S bond breaking. We demonstrate that plasmon-induced photodesorption enables subdiffraction and even subparticle multiplexing. Finally, we explore possible routes to further exploit these concepts for the selective positioning of nanomaterials and the sorting and purification of colloidal nanoparticles.
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