59 results found
The use of nanoplasmonics to control light and heat close to the thermodynamic limit enables exciting opportunities in the field of plasmonic catalysis. The decay of plasmonic excitations creates highly nonequilibrium distributions of hot carriers that can initiate or catalyze reactions through both thermal and nonthermal pathways. In this Perspective, we present the current understanding in the field of plasmonic catalysis, capturing vibrant debates in the literature, and discuss future avenues of exploration to overcome critical bottlenecks. Our Perspective spans first-principles theory and computation of correlated and far-from-equilibrium light-matter interactions, synthesis of new nanoplasmonic hybrids, and new steady-state and ultrafast spectroscopic probes of interactions in plasmonic catalysis, recognizing the key contributions of each discipline in realizing the promise of plasmonic catalysis. We conclude with our vision for fundamental and technological advances in the field of plasmon-driven chemical reactions in the coming years.
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
Lee JB, Walker H, Li Y, et al., 2020, Template Dissolution Interfacial Patterning of Single Colloids for Nanoelectrochemistry and Nanosensing., ACS Nano
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.
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
Poblet M, Li Y, Cortés E, et al., 2020, Direct Detection of Optical Forces of Magnetic Nature in Dielectric Nanoantennas., Nano Lett, Vol: 20, Pages: 7627-7634
Optical forces on nanostructures are usually characterized by their interaction with the electric field component of the light wave, given that most materials present negligible magnetic response at optical frequencies. This is not the case however of a high-refractive-index dielectric nanoantenna, which has been recently shown to efficiently support both electric and magnetic optical modes. In this work, we use a photoinduced force microscopy configuration to measure optically induced forces produced by a germanium nanoantenna on a surrounding silicon near-field probe. We reveal the spatial distribution, character, and magnitude of the generated forces when exciting the nanoantenna at its anapole state condition. We retrieve optical force maps showing values of up to 20 pN, which are found to be mainly magnetic in nature, according to our numerical simulations. The results of this investigation open new pathways for the study, detection, and generation of magnetic light forces at the nanometer scale.
Barella M, Violi IL, Gargiulo J, et al., 2020, In Situ Photothermal Response of Single Gold Nanoparticles through Hyperspectral Imaging Anti-Stokes Thermometry., ACS Nano
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.
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
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
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
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.
Doiron B, Gusken NA, Lauri A, et al., 2020, Hot Carrier Optoelectronics with Titanium Nitride, Lasers and Electro-Optics Society Annual Meeting-LEOS, ISSN: 1092-8081
© 2020 OSA. Titanium oxynitride enables a range of plasmonic and optoelectronic functionality using long-lived photo-generated hot carriers. We explore the time scale of hot carriers in TiN and their use in photochemical reduction and Schottky detectors.
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
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
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, Peveler WJ, et al., 2020, Enhancing hybrid metal-semiconductor systems beyond SERS with PIERS (Photo-induced enhanced Raman scattering) for trace analyte detection, Conference on Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XXI held at SPIE Defense + Commercial Sensing Conference, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
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
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
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
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
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
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.
Gargiulo J, Violi IL, Cerrota S, et al., 2017, Accuracy and Mechanistic Details of Optical Printing of Single Au and Ag Nanoparticles, ACS NANO, Vol: 11, Pages: 9678-9688, ISSN: 1936-0851
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