1. |
- Hu, L., et al.
(författare)
-
Fano resonance assisting plasmonic circular dichroism from nanorice heterodimers for extrinsic chirality
- 2015
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the circular dichroisms (CD) of nanorice heterodimers consisting of two parallel arranged nanorices with the same size but different materials are investigated theoretically. Symmetry-breaking is introduced by using different materials and oblique incidence to achieve strong CD at the vicinity of Fano resonance peaks. We demonstrate that all Au-Ag heterodimers exhibit multipolar Fano resonances and strong CD effect. A simple quantitative analysis shows that the structure with larger Fano asymmetry factor has stronger CD. The intensity and peak positions of the CD effect can be flexibly tuned in a large range by changing particle size, shape, the inter-particle distance and surroundings. Furthermore, CD spectra exhibit high sensitivity to ambient medium in visible and near infrared regions. Our results here are beneficial for the design and application of high sensitive CD sensors and other related fields.
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2. |
- Hu, L., et al.
(författare)
-
Quantitatively analyzing the mechanism of giant circular dichroism in extrinsic plasmonic chiral nanostructures by tracking the interplay of electric and magnetic dipoles
- 2016
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 8:6, s. 3720-3728
-
Tidskriftsartikel (refereegranskat)abstract
- Plasmonic chirality has drawn much attention because of tunable circular dichroism (CD) and the enhancement for chiral molecule signals. Although various mechanisms have been proposed to explain the plasmonic CD, a quantitative explanation like the ab initio mechanism for chiral molecules, is still unavailable. In this study, a mechanism similar to the mechanisms associated with chiral molecules was analyzed. The giant extrinsic circular dichroism of a plasmonic splitting rectangle ring was quantitatively investigated from a theoretical standpoint. The interplay of the electric and magnetic modes of the meta-structure is proposed to explain the giant CD. We analyzed the interplay using both an analytical coupled electric-magnetic dipole model and a finite element method model. The surface charge distributions showed that the circular current yielded by the splitting rectangle ring causes the ring to behave like a magneton at some resonant modes, which then interact with the electric modes, resulting in a mixing of the two types of modes. The strong interplay of the two mode types is primarily responsible for the giant CD. The analysis of the chiral near-field of the structure shows potential applications for chiral molecule sensing.
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3. |
- Cui, L., et al.
(författare)
-
A plasmon-driven selective surface catalytic reaction revealed by surface-enhanced Raman scattering in an electrochemical environment
- 2015
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 5, s. Art. no. 11920 -
-
Tidskriftsartikel (refereegranskat)abstract
- Plasmonic catalytic reactions of molecules with single amine or nitro groups have been investigated in recent years. However, plasmonic catalysis of molecules with multiple amine and/or nitro groups is still unknown. In this paper, plasmon-driven catalytic reactions of 4,4'-dinitroazobenzene (DNAB), 4,4'-diaminoazobenzene (DAAB) and 4-nitro-4'-aminoazobenzene (NAAB) are investigated using electrochemical surface-enhanced Raman scattering (SERS) spectroscopy. The results reveal that a plasmon-driven reduction reaction occurred for DNAB and NAAB in which the NO 2 group was reduced to NH 2, while the plasmon-driven oxidation reaction of NH 2 did not occur. This result demonstrates that plasmon-driven reduction reactions are much easier than plasmon-driven oxidization reactions in electrochemical environments. The molecular resonance may also play an important role in plasmon-driven catalytic reactions. These findings provide us with a deeper understanding of plasmon-driven catalytic reactions.
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4. |
- Cui, L., et al.
(författare)
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Plasmon-driven dimerization via S-S chemical bond in an aqueous environment
- 2014
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 4
-
Tidskriftsartikel (refereegranskat)abstract
- The surface-enhanced Raman scattering (SERS) spectra of thioanisole are experimentally investigated in an electrochemical environment in this study. Two Raman peaks, which depend strongly not only on electric potential but also on the local surface plasmon resonances (LSPR), have been observed. Theoretical calculations reveal that thioanisole is first dissociated from thiophenol via the S-CH3 bond; plasmons then drive the dimerisation of thiophenol via the S-S bond, which is strongly potential dependent. One Raman peak corresponds to the S-S vibrational mode of the thiophenol dimer, and the other corresponds to the asymmetric C-C stretching modes of the benzenyl of the thiophenol dimer. The potential-dependent two Raman modes is the potential-dependent dimerisation dynamics of thiophenol via the S-S bond. Our experimental findings provide insight into the structural elucidation of adsorbed molecules and molecular surface reaction dynamics.
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5. |
- Dong, Bin, et al.
(författare)
-
Is 4-nitrobenzenethiol converted to p,p '-dimercaptoazobenzene or 4-aminothiophenol by surface photochemistry reaction?
- 2011
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Ingår i: Journal of Raman Spectroscopy. - : Wiley. - 1097-4555 .- 0377-0486. ; 42:6, s. 1205-1206
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Tidskriftsartikel (refereegranskat)abstract
- For the first time, the experimental and theoretical evidence for the conversion of 4-nitrobenzenethiol (4-NBT) to p,p'-dimercaptoazobenzene (DMAB) in Ag and Cu sols by surface photochemistry reaction is obtained with surface-enhanced Raman scattering (SERS) spectroscopy. The SERS spectrum of 4-NBT in Cu sol is identical to that of DMAB produced from 4-aminothiophenol in Ag sol as reported in recent literature, thereby providing direct spectral evidence. Copyright (C) 2011 John Wiley & Sons, Ltd.
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6. |
- Dong, Bin, et al.
(författare)
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Local and Remote Charge-Transfer-Enhanced Raman Scattering on One-Dimensional Transition-Metal Oxides
- 2010
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Ingår i: Chemistry - An Asian Journal. - : Wiley. - 1861-4728. ; 5:8, s. 1824-1829
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Tidskriftsartikel (refereegranskat)abstract
- The one-dimensional (1D) transition-metal oxide MoO3 belt is synthesized and characterized with Xray diffraction, scanning electron microscopy, and Raman spectroscopy. Charge-transfer-(CT) enhanced Raman scattering of 4-mercaptobenzoic acid (4-MBA) on a 1D MoO3 belt was investigated experimentally and theoretically. The chemical enhancement of surface-enhanced Raman scattering (SERS) of 4-MBA on the MoO3 belt by CT is in the order of 10(3). The SERS of 4-MBA was investigated theoretically by using a quantum chemical method. The remote SERS of 4-MBA along the 1D MoO3 belt (the light excitation to one side of the MoO3 belt, and the SERS spectrum is collected on the other side of the MoO3 belt) is also shown experimentally, which provides potential applications of SERS. The incident polarization dependence of remote SERS spectra has also been investigated experimentally.
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7. |
- Dong, B., et al.
(författare)
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Local surface plasmon resonance of single silver nanorice particles in the near-infrared
- 2014
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Ingår i: Mikrochimica Acta. - : Springer Science and Business Media LLC. - 1436-5073 .- 0026-3672. ; 181:7-8, s. 791-795
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Tidskriftsartikel (refereegranskat)abstract
- We report on the synthesis and optical spectra of silver nanorice particles. Two strong absorption bands are resolved in the near UV and near-IR region, and the dark field scattering spectra are consistent with the absorption spectra. Finite-difference time-domain simulations reveal that the peak in the IR region can be attributed to the E field that is parallel to the long axis, while the peak in the UV can be attributed to the E field perpendicular to the short axis of the silver nanorice particles.
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8. |
- Dong, Bin, et al.
(författare)
-
Substrate-, Wavelength-, and Time-Dependent Plasmon-Assisted Surface Catalysis Reaction of 4-Nitrobenzenethiol Dimerizing to p,p '-Dimercaptoazobenzene on Au, Ag, and Cu Films
- 2011
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 27:17, s. 10677-10682
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we experimentally investigate the substrate, wavelength, and time dependence of the plasmon-assisted surface-catalyzed dimerization of 4-nitrobenzenethiol to form p,p'-dimercaptoazobenzene on Au, Ag, and Cu films. We provide direct experimental evidence that surface plasmon resonance plays the most important role in these surface-catalyzed reactions. It is found that the reaction is strongly dependent on the substrate, the wavelength of the laser, and the reaction timescales. Our experimental results revealed that optimal experimental conditions can be rationally chosen to control (accelerate or restrain) this reaction. The experimental results are also confirmed by theoretical calculations.
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9. |
- Fang, Yurui, et al.
(författare)
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Ascertaining p,p '-Dimercaptoazobenzene Produced from p-Aminothiophenol by Selective Catalytic Coupling Reaction on Silver Nanoparticles
- 2010
-
Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 26:11, s. 7737-7746
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Tidskriftsartikel (refereegranskat)abstract
- Combining experiment and theory, evidence from surface-enhanced Raman scattering (SERS) were obtained for p,p'-dimercaptoazobenzene (DMAB) produced from p-aminothiophenol (PATP) by selective catalytic coupling reaction on silver nanoparticles. The time-dependent SERS spectra of PATE are consistent with the calculated SERS spectra of DMAB), which is the direct evidence or the production of DMAB from PATE by selective catalytic coupling reaction on silver nanoparticles. The so-called "b(2) modes" of PATP is the -N=N- related vibrational modes of DMAB. The silver nanoparticles could be assembled together to form different size of aggregates with different concentration of PATE solution. When the concentration of Ag nanoparticle (the radius 40 nm) in colloid is 35 pM, the time-dependent SERS of DMA B reveals that the better experimental conditions for observing SERS signals of DMA B are (1) concentration of PATE is around 5 x 0(-6) M in which condition the aggregates consist with about 3-5 silver nanoparticles. which are not too big and suitable for SERS measurement, and (2) the Raman signal will be strongest at the thne delay about 27 min for this concentration. By analyzing the symmetry of strong enhanced vibrational modes, it is derived that all ask strong vibrational modes are mostly enhanced by surface plasmons (electromagnetic field). The SERS enhancement calculated with finite-difference time-domain method is on the order of |M|(4) = 9.0 x 10(8) in junctions of AgNPs at 632.8 nm, where |M|(4) = E-loc/E-in and E-loc and E-in are local and incident electric fields, respectively. The total chemical enhancements, including static chemical and resonant enhancements, are on the order of 10(3).
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10. |
- Fang, Yurui, et al.
(författare)
-
Branched Silver Nanowires as Controllable Plasmon Routers
- 2010
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 10:5, s. 1950-1954
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Tidskriftsartikel (refereegranskat)abstract
- Using polarization dependent scattering spectroscopy, we investigate plasmon propagation on branched silver nanowires. By controlling the polarization of the incident laser light, the wire plasmons can be routed into different wire branches and result in light emission from the corresponding wire ends. This routing behavior is found to be strongly dependent on the wavelength of light. Thus for certain incident polarizations, light of different wavelength will be routed into different branches. The branched nanowire can thus serve as a controllable router and multiplexer in integrated plasmonic circuits.
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11. |
- Fang, Yurui, 1983, et al.
(författare)
-
Electromagnetic field redistribution in coupled plasmonic nanoparticle dimer-dielectric substrate system
- 2015
-
Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 619, s. 139-143
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Tidskriftsartikel (refereegranskat)abstract
- Combining simulations and experiments, we demonstrate that the surface enhanced Raman scattering (SERS) system of a metal nanoparticle dimer on a dielectric substrate shows strong electromagnetic field enhancement in the particle/substrate gap because of the electromagnetic field redistribution. Besides, in some configurations, the presence of the substrate makes the strongest field enhancement in the gap between the two nanoparticles (i.e. the dimer) occur at the quadruple resonance, not the dipole resonance as usual. The result is very instructive in the difference between the ideal theoretical systems and the real experimental configuration.
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12. |
- Fang, Yurui, 1983, et al.
(författare)
-
Electromagnetic field redistribution in hybridized plasmonic particle-film system
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 102:15, s. artikel nr 153108-
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Tidskriftsartikel (refereegranskat)abstract
- Combining simulation and experiment, we demonstrate that a metal nanoparticle dimer on a gold film substrate can confine more energy in the particle/film gap because of the hybridization of the dimer resonant lever and the continuous state of the film. The hybridization may even make the electric field enhancement in the dimer/film gap stronger than in the gap between particles. The resonant peak can be tuned by varying the size of the particles and the film thickness. This electromagnetic field redistribution has tremendous applications in sensor, photocatalysis and solar cell, etc., especially considering ultrasensitive detection of tracing molecule on substrates.
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13. |
- Fang, Yurui, 1983, et al.
(författare)
-
High vacuum tip-enhanced Raman spectroscope based on a scanning tunneling microscope
- 2016
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 87:3, s. 033104-
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present the construction of a high-vacuum tip-enhanced Raman spectroscopy (HV-TERS) system that allows in situ sample preparation and measurement. A detailed description of the prototype instrument is presented with experimental validation of its use and novel ex situ experimental results using the HV-TERS system. The HV-TERS system includes three chambers held under a 10(-7) Pa vacuum. The three chambers are an analysis chamber, a sample preparation chamber, and a fast loading chamber. The analysis chamber is the core chamber and contains a scanning tunneling microscope (STM) and a Raman detector coupled with a 50 x 0.5 numerical aperture objective. The sample preparation chamber is used to produce single-crystalline metal and sub-monolayer molecular films by molecular beam epitaxy. The fast loading chamber allows ex situ preparation of samples for HV-TERS analysis. Atomic resolution can be achieved by the STM on highly ordered pyrolytic graphite. We demonstrate the measurement of localized temperature using the Stokes and anti-Stokes TERS signals from a monolayer of 1,2-benzenedithiol on a gold film using a gold tip. Additionally, plasmonic catalysis can be monitored label-free at the nanoscale using our device. Moreover, the HV-TERS experiments show simultaneously activated infrared and Raman vibrational modes, Fermi resonance, and some other non-linear effects that are not observed in atmospheric TERS experiments. The high spatial and spectral resolution and pure environment of high vacuum are beneficial for basic surface studies.
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14. |
- Fang, Yurui, 1983, et al.
(författare)
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Hot Electron Generation and Cathodoluminescence Nanoscopy of Chiral Split Ring Resonators
- 2016
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 16:8, s. 5183-5190
-
Tidskriftsartikel (refereegranskat)abstract
- Three-dimensional chiral plasmonic nanostructures have been shown to be able to dramatically boost photon-spin selective light-matter interactions, potentially leading to novel photonics, molecular spectroscopy, and light-harvesting applications based on circularly polarized light. Here, we show that chiral split-ring gold nanoresonators interfaced to a wide band gap semiconductor exhibit a contrast in hot-electron transfer rate between left-handed and right-handed visible light that essentially mimics the far-field circular dichroism of the structures. We trace down the origin of this effect to the differential excitation of the thinnest part of the split-ring structures using dichroic-sensitive cathodoluminescence imaging with nanometer spatial resolution. The results highlight the intricate interplay between the near-field and far field chiral response of a nanostructure and establishes a clear link to the emerging field of hot carrier plasmonics with numerous potential applications in photocatalysis and solar light harvesting.
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15. |
- Fang, Yurui, 1983, et al.
(författare)
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Nanoplasmonic waveguides: Towards applications in integrated nanophotonic circuits
- 2015
-
Ingår i: Light: Science and Applications. - : Springer Science and Business Media LLC. - 2047-7538 .- 2095-5545. ; 4
-
Forskningsöversikt (refereegranskat)abstract
- The properties of propagating surface plasmon polaritons (SPPs) along one-dimensional metal structures have been investigated for more than 10 years and are now well understood. Because of the high confinement of electromagnetic energy, propagating SPPs have been considered to represent one of the best potential ways to construct next-generation circuits that use light to overcome the speed limit of electronics. Many basic plasmonic components have already been developed. In this review, researches on plasmonic waveguides are reviewed from the perspective of plasmonic circuits. Several circuit components are constructed to demonstrate the basic function of an optical digital circuit. In the end of this review, a prototype for an SPP-based nanochip is proposed, and the problems associated with building such plasmonic circuits are discussed. A plasmonic chip that can be practically applied is expected to become available in the near future.
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16. |
- Fang, Yurui, 1983, et al.
(författare)
-
Near field plasmonic gradient effects on high vacuum tip-enhanced Raman spectroscopy
- 2015
-
Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 17:2, s. 783-794
-
Tidskriftsartikel (refereegranskat)abstract
- Near field gradient effects in high vacuum tip-enhanced Raman spectroscopy (HV-TERS) are a recent developing ultra-sensitive optical and spectral analysis technology on the nanoscale, based on the plasmons and plasmonic gradient enhancement in the near field and under high vacuum. HV-TERS can not only be used to detect ultra-sensitive Raman spectra enhanced by surface plasmon, but also to detect clear molecular IR-active modes enhanced by strongly plasmonic gradient. Furthermore, the molecular overtone modes and combinational modes can also be experimentally measured, where the Fermi resonance and Darling-Dennison resonance were successfully observed in HV-TERS. Theoretical calculations using electromagnetic field theory firmly supported experimental observation. The intensity ratio of the plasmon gradient term over the linear plasmon term can reach values greater than 1. Theoretical calculations also revealed that with the increase in gap distance between tip and substrate, the decrease in the plasmon gradient was more significant than the decrease in plasmon intensity, which is the reason that the gradient Raman can be only observed in the near field. Recent experimental results of near field gradient effects on HV-TERS were summarized, following the section of the theoretical analysis.
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17. |
- Fang, Yurui, 1983, et al.
(författare)
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Photoemission Enhancement of Plasmonic Hot Electrons by Au Antenna-Sensitizer Complexes
- 2024
-
Ingår i: ACS Nano. - 1936-086X .- 1936-0851. ; 18:4, s. 3397-3404
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Tidskriftsartikel (refereegranskat)abstract
- The photoemission of surface plasmon decay-produced hot electrons is usually of very low efficiencies, hindering the practical utilization of such nonequilibrium charge carriers in harvesting photons with less energy than the semiconductor band gap for more efficient solar energy collection and photodetection. However, it has been demonstrated that the photoemission efficiency of small metal clusters increases as the particle size decreases. Recent studies have also shown that the photoemission efficiency of surface plasmon-yielded hot carriers can be intrinsically improved through proper material construction. In this paper, we report that the photoemission efficiency of hot electrons on the Au nanodisk-cluster complex/TiO2 interface can be dramatically enhanced under optical nanoantenna-sensitizer design. Such an enhancement is dominantly attributed to three factors. First, the large plasmonic nanodisk antennas provide a significantly enhanced optical near field, which largely increases light absorption in the small Au clusters that are acting as hot electron injection sensitizers. Second, the sub-3 nm size of the Au clusters facilitates the collection of delocalized spreading charges by the semiconductor. Third, the hybrid interface and molecule-like energy level of the Au cluster result in a much longer lifetime of excited electrons. Our results provide a promising approach for the effective harvesting of solar energy with plasmonic antenna-sensitizer complexes.
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18. |
- Fang, Yurui, 1983, et al.
(författare)
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Plasmon Enhanced Internal Photoemission in Antenna-Spacer-Mirror Based Au/TiO2 Nanostructures
- 2015
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 15:6, s. 4059-4065
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Tidskriftsartikel (refereegranskat)abstract
- Emission of photoexcited hot electrons from plasmonic metal nanostructures to semiconductors is key to a number of proposed nanophotonics technologies for Solar harvesting, water splitting, photocatalysis, and a variety of optical sensing and photodetector applications. Favorable materials and catalytic properties make systems based on gold and TiO2 particularly interesting, but the internal photo emission efficiency for visible light is low because of the wide bandgap of the semiconductor. We investigated the incident photon-to-electron conversion efficiency of thin TiO2 films decorated with Au nanodisk antennas in an electrochemical circuit and found that incorporation of a Au mirror beneath the semiconductor amplified the photoresponse for light with wavelength lambda = 500-950 nm by a factor 2-10 compared to identical structures lacking the mirror component. Classical electrodynamics simulations showed that the enhancement effect is caused by a favorable interplay between localized surface plasmon excitations and cavity modes that together amplify the light absorption in the Au/TiO2 interface. The experimentally determined internal quantum efficiency for hot electron transfer decreases monotonically with wavelength, similar to the probability for interband excitations with energy higher than the Schottky barrier obtained from a density functional theory band structure simulation of a thin Au/TiO2 slab.
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19. |
- Fang, Yurui, et al.
(författare)
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Remote-Excitation Surface-Enhanced Raman Scattering Using Propagating Ag Nanowire Plasmons.
- 2009
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 9:5, s. 2049-2053
-
Tidskriftsartikel (refereegranskat)abstract
- Using propagating plasmons on silver nanowires as an excitation source we perform surface-enhanced Raman scattering (SERS) at a nanoparticle/wire junction located remotely from the laser illumination spot with sensitivities in a few molecules range. Simultaneous multisite remote-excitation SERS sensing can also be achieved.
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20. |
- Fang, Yurui, 1983, et al.
(författare)
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Resonant surface plasmons of a metal nanosphere treated as propagating surface plasmons
- 2018
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Ingår i: Chinese Physics B. - : IOP Publishing. - 1674-1056. ; 27:6
-
Tidskriftsartikel (refereegranskat)abstract
- On the assumption that the resonant surface plasmons on a spherical nanoparticle are formed by standing waves of two counter-propagating surface plasmon waves along the surface, by using Mie theory simulation, we find that the dispersions of surface plasmon resonant modes supported by silver nanospheres match with those of the surface plasmons on a semiinfinite medium-silver interface very well. This suggests that the resonant surface plasmons of a metal nanosphere can be treated as a propagating surface plasmon wave.
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21. |
- Hu, L., et al.
(författare)
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Analyzing intrinsic plasmonic chirality by tracking the interplay of electric and magnetic dipole modes
- 2017
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 7:1
-
Tidskriftsartikel (refereegranskat)abstract
- Plasmonic chirality represents significant potential for novel nanooptical devices due to its association with strong chiroptical responses. Previous reports on plasmonic chirality mechanism mainly focus on phase retardation and coupling. In this paper, we propose a model similar to the chiral molecules for explaining the intrinsic plasmonic chirality mechanism of varies 3D chiral structures quantitatively based on the interplay and mixing of electric and magnetic dipole modes (directly from electromagnetic field numerical simulations), which forms mixed electric and magnetic polarizability.
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22. |
- Huang, Y. Z., et al.
(författare)
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Nanowire-supported plasmonic waveguide for remote excitation of surface-enhanced Raman scattering
- 2014
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Ingår i: Light: Science and Applications. - : Springer Science and Business Media LLC. - 2047-7538 .- 2095-5545. ; 3, s. Art. no. e199-
-
Forskningsöversikt (refereegranskat)abstract
- Due to its amazing ability to manipulate light at the nanoscale, plasmonics has become one of the most interesting topics in the field of light-matter interaction. As a promising application of plasmonics, surface-enhanced Raman scattering (SERS) has been widely used in scientific investigations and material analysis. The large enhanced Raman signals are mainly caused by the extremely enhanced electromagnetic field that results from localized surface plasmon polaritons. Recently, a novel SERS technology called remote SERS has been reported, combining both localized surface plasmon polaritons and propagating surface plasmon polaritons (PSPPs, or called plasmonic waveguide), which may be found in prominent applications in special circumstances compared to traditional local SERS. In this article, we review the mechanism of remote SERS and its development since it was first reported in 2009. Various remote metal systems based on plasmonic waveguides, such as nanoparticle-nanowire systems, single nanowire systems, crossed nanowire systems and nanowire dimer systems, are introduced, and recent novel applications, such as sensors, plasmon-driven surface-catalyzed reactions and Raman optical activity, are also presented. Furthermore, studies of remote SERS in dielectric and organic systems based on dielectric waveguides remind us that this useful technology has additional, tremendous application prospects that have not been realized in metal systems.
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23. |
- Jiao, Yang, 1985, et al.
(författare)
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Schottky barrier formation and band bending revealed by first- principles calculations
- 2015
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 5, s. Art. no. 11374-
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Tidskriftsartikel (refereegranskat)abstract
- The formation of a Schottky barrier at the metal-semiconductor interface is widely utilised in semiconductor devices. With the emerging of novel Schottky barrier based nanoelectronics, a further microscopic understanding of this interface is in high demand. Here we provide an atomistic insight into potential barrier formation and band bending by ab initio simulations and model analysis of a prototype Schottky diode, i.e., niobium doped rutile titania in contact with gold (Au/Nb:TiO2). The local Schottky barrier height is found to vary between 0 and 1.26 eV depending on the position of the dopant. The band bending is caused by a dopant induced dipole field between the interface and the dopant site, whereas the pristine Au/TiO2 interface does not show any band bending. These findings open the possibility for atomic scale optimisation of the Schottky barrier and light harvesting in metal-semiconductor nanostructures.
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24. |
- Li, Y. Q., et al.
(författare)
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Time-Resolved Photoluminescence Spectroscopy of Exciton-Plasmon Coupling Dynamics
- 2015
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Ingår i: Plasmonics. - : Springer Science and Business Media LLC. - 1557-1963 .- 1557-1955. ; 10:2, s. 271-280
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Tidskriftsartikel (refereegranskat)abstract
- In this review, we provide a brief overview of the recent progress achieved on the plasmon-enhanced fluorescence technique for the study of exciton-plasmon interactions using time-resolved photoluminescence spectroscopy. Quantum emitters situated in regions of localized field enhancement are excited by the enhanced electromagnetic field intensity. During the emission process, both the radiative decay rate and nonradiative decay rate can be increased by the enhanced electromagnetic field. These can be distinguished using two methods, either by neglecting the excitation rate enhancement when the excitation wavelength is far from the surface plasmon resonance or by assuming that the enhancement of the excitation is the same as the radiative decay rate. This review aims to provide a comprehensive understanding of the time-resolved photoluminescence spectroscopy of exciton-plasmon coupling dynamics.
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25. |
- Li, Zhipeng, et al.
(författare)
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Correlation between Incident and Emission Polarization in Nanowire Surface Plasmon Waveguides
- 2010
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 10:5, s. 1831-1835
-
Tidskriftsartikel (refereegranskat)abstract
- Nanowire plasmons can be launched by illumination at one terminus of the nanowire and emission can be detected at the other end of the wire. Using polarization dependent dark-held scattering spectroscopy, we measure how the polarization of the emitted light depends on the polarization of the incident light. We observe that the shape of the nanowire termination plays an important role in determining this polarization change. Depending on termination shape, a nanowire can serve as either a polarization-maintaining waveguide, or as a polarization-rotating, nanoscale half-wave plate. The understanding of how plasmonic waveguiding influence the polarization of the guided light is important for optimizing the structure of integrated plasmonic devices
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26. |
- Li, Zhipeng, et al.
(författare)
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Directional Light Emission from Propagating Surface Plasmons of Silver Nanowires.
- 2009
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 9:Online September 21, 2009, s. 4383-4386
-
Tidskriftsartikel (refereegranskat)abstract
- Thin metallic nanowires are highly promising candidates for plasmonic waveguides in photonic and electronic devices. We have observed that light from the end of a silver nanowire, following excitation of plasmons at the other end of the wire, is emitted in a cone of angles peaking at nominally 45-60 degrees from the nanowire axis, with virtually no light emitted along the direction of the nanowire. This surprising characteristic can be explained in a simple picture invoking Fabry-Perot resonances of the forward- and back-propagating plasmons on the nanowire. This strongly angular-dependent emission is a critical property that must be considered when designing coupled nanowire-based photonic devices and systems.
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27. |
- Li, Zhipeng, et al.
(författare)
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Effect of a proximal substrate on plasmon propagation in silver nanowires
- 2010
-
Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 82:24
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Tidskriftsartikel (refereegranskat)abstract
- We investigate how the properties of a nearby substrate modify the excitation and propagation of plasmons in subwavelength silver wires. With decreasing nanowire-substrate separation, the in-coupling efficiency shows strongly oscillatory behavior due to coherent interference. The plasmon damping increases with decreasing separation due to an increased coupling of the nanowire plasmons to the photonic modes of the substrate.
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28. |
- Liu, T., et al.
(författare)
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Heterodimer Nanostructures Induced Energy Focusing on Metal Film
- 2016
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 120:14, s. 7778-7784
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Tidskriftsartikel (refereegranskat)abstract
- As a newly discovered surface plasmon resonance system, the nanoparticle dimer film structure provides a novel approach to enhance light power on a plane film due to the redistribution of the electromagnetic field. This structure has been widely applied in surface enhanced Raman scattering (SERS), solar cells, photocatalysis, etc., especially for the homodimer film case. However, the properties of heterodimers on film still remain unclear. In this work, the effect of particle size on electromagnetic field redistribution for a Ag nanoparticle dimer on Au film system is investigated first. The results obtained from the finite element method indicate that a smaller nanoparticle has much greater ability to focus light energy on Au film, and the corresponding energy can be 5 times stronger than that of the larger nanoparticle case. Further research indicates that this energy focusing ability has a strong relationship to the wavelength and the diameter ratio of the dimer. A similar focusing phenomenon has been found in the system of thick nanowire small nanoparticle on film. Then the SERS spectra collected in the small nanoparticle large nanowire system provide experimental evidence for this theoretical predication. Our results strengthen the understanding of surface plasmon on plane film and have potential applications in surface plasmon related fields.
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29. |
- Ogier, Robin, 1987, et al.
(författare)
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Macroscopic Layers of Chiral Plasmonic Nanoparticle Oligomers from Colloidal Lithography
- 2014
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Ingår i: ACS Photonics. - : American Chemical Society (ACS). - 2330-4022. ; 1:10, s. 1074-1081
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Tidskriftsartikel (refereegranskat)abstract
- Optical near-field coupling between closely spaced plasmonic metal nanoparticles is important to a range of nanophotonic applications of high contemporary interest, including surface-enhanced molecular spectroscopy, nanooptical sensing, and various novel light-harvesting concepts. Here we report on monolayers of chiral heterotrimers and heterotetramers composed of closely spaced silver and/or gold nanodisks of different heights fabricated through facile hole-mask colloidal lithography. These quasi-three-dimensional oligomers are interesting for applications because they exhibit "hot" gaps and crevices of nanometric dimensions, a pronounced circular dichroism, and optical chirality in the visible to near-infrared wavelength range, and they can be produced in large ensembles (>109) of identical orientation. We analyze the optical properties of the samples based on simulation results and find that the circular dichroism is due to strong near-field coupling and intricate phase retardation effects originating in the three-dimensional character of the individual oligomers.
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30. |
- Ogier, Robin, 1987, et al.
(författare)
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Near-Complete Photon Spin Selectivity in a Metasurface of Anisotropic Plasmonic Antennas
- 2015
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Ingår i: Physical Review X. - : American Physical Society. - 2160-3308. ; 5:4
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Tidskriftsartikel (refereegranskat)abstract
- Simple chiroptically active metamaterials are difficult to realize in practice but could pave the way for a range of important applications, such as sensitive optical biosensors, asymmetric catalysis, and novel polarization manipulation devices. We show that a metasurface based on a random arrangement of anisotropic but aligned gold nanoparticles can exhibit an almost perfect selectivity towards incident photon spin for evanescent excitation with visible to near-infrared light. The experimentally attained reflection contrast between left- and right-handed circularly polarized light peaks at similar to 90%, in excellent agreement with analytical theory. These results are important for the development of future photonic and plasmonic polarization-based technologies.
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31. |
- Sun, Mengtao, et al.
(författare)
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Activated vibrational modes and Fermi resonance in tip-enhanced Raman spectroscopy
- 2013
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Ingår i: Physical Review E (Statistical, Nonlinear, and Soft Matter Physics). - 1539-3755. ; 87:2
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Tidskriftsartikel (refereegranskat)abstract
- Using p-aminothiophenol (PATP) molecules on a gold substrate and high-vacuum tip-enhanced Raman spectroscopy (HV-TERS), we show that the vibrational spectra of these molecules are distinctly different from those in typical surface-enhanced Raman spectroscopy. Detailed first-principles calculations help to assign the Raman peaks in the TERS measurements as Raman-active and IR-active vibrational modes of dimercaptoazobenzene (DMAB), providing strong spectroscopic evidence for the dimerization of PATP molecules to DMAB under the TERS setup. The activation of the IR-active modes is due to enhanced electromagnetic field gradient effects within the gap region of the highly asymmetric tip-surface geometry. Fermi resonances are also observed in HV-TERS. These findings help to broaden the versatility of TERS as a promising technique for ultrasensitive molecular spectroscopy. DOI:10.1103/PhysRevE.87.020401
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32. |
- Sun, Mengtao, et al.
(författare)
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Chemical and electromagnetic mechanisms of tip-enhanced Raman scattering
- 2009
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 11:41, s. 9412-9419
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we attempt to reveal the nature of the chemical and electromagnetic mechanisms of tip-enhanced Raman scattering (TERS). Direct visual evidence regarding the chemical mechanism via charge transfer was obtained with charge difference density. It is found that there are several kinds of charge transfer: (1) tip to molecule, (2) surface to molecule, (3) tip and surface to molecule simultaneously, and (4) tunneling charge transfer between the tip and the surface. Direct evidence regarding the electromagnetic mechanism via intracluster (tip or surface) charge redistribution was also revealed via charge difference density. The distance (between tip and surface) dependence of the near electric field distribution and the TERS enhancement at different incident lights is also discussed using the three-dimensional finite-difference time-domain (FDTD) method. The electromagnetic enhancement of double-tip TERS is approximately 10 times larger than that of conventional TERS. Theoretical results reveal that plasmon coupling effects between the metal tip and surface play an important role in TERS.
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33. |
- Sun, Mengtao, et al.
(författare)
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Near- and Deep-Ultraviolet Resonance Raman Spectroscopy of Pyrazine-Al-4 Complex and Al-3-Pyrazine-Al-3 Junction
- 2009
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 113:44, s. 19328-19334
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Tidskriftsartikel (refereegranskat)abstract
- Near- and deep-ultraviolet (UV) resonance Raman spectroscopy of pyrazine-Al-4 complex and Al-3-pyrazine-Al-3 junction was investigated theoretically with a quantum chemical method. Here, 325 and 244 nm were employed as near- and deep-UV sources in our theoretical study The intensities of static normal Raman spectra of pyrazine-Al-4 complex and Al-3-pyrazine-Al-3 junction were enhanced oil the orders of 10 and 10(3) by a static chemical mechanism, respectively The calculated absorption spectra reveal strong B-6(2) and B-13(2u) electronic transitions near 325 nm for pyrazine-Al-4 complex and 244 nm for Al-3-pyrazine-Al-3 junction, respectively. The analyses of orbital transitions in electronic transitions reveal they are the mixture of (metal to molecule) charge transfer excitation and intracluster excitation. The intensity of near-UV resonance Raman spectroscopy of pyrazine-Al-4 complex and the intensity of deep-UV resonance Raman spectroscopy of Al-3-pyrazine-Al-3 junction are strongly enhanced on the order of 10(5) and 10(4), respectively, compared to the Raman intensity of isolated pyrazine excited at 325 and 244 nm. The calculations of Mic theory and the three-dimensional finite-difference time domain method reveal strong surface plasmon resonance and strong electromagnetic enhancements at 325 and 244 nm for single and dimer nanoparticles at suitable sizes and gap distance, respectively. The strongest SERS enhancement in the system of junction is on the order of 10(8) at the incident lights of 325 and 244 nm. The total enhancements, including the chemical and electromagnetic enhancements, can reach Lip to 10(13). So, Al is a suitable material for near- and deep-UV surface-enhanced resonance Raman scattering
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34. |
- Tian, X. R., et al.
(författare)
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Formation of Enhanced Uniform Chiral Fields in Symmetric Dimer Nanostructures
- 2015
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 5, s. Article no. 17534-
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Tidskriftsartikel (refereegranskat)abstract
- Chiral fields with large optical chirality are very important in chiral molecules analysis, sensing and other measurements. Plasmonic nanostructures have been proposed to realize such super chiral fields for enhancing weak chiral signals. However, most of them cannot provide uniform chiral near-fields close to the structures, which makes these nanostructures not so efficient for applications. Plasmonic helical nanostructures and blocked squares have been proved to provide uniform chiral near-fields, but structure fabrication is a challenge. In this paper, we show that very simple plasmonic dimer structures can provide uniform chiral fields in the gaps with large enhancement of both near electric fields and chiral fields under linearly polarized light illumination with polarization off the dimer axis at dipole resonance. An analytical dipole model is utilized to explain this behavior theoretically. 30 times of volume averaged chiral field enhancement is gotten in the whole gap. Chiral fields with opposite handedness can be obtained simply by changing the polarization to the other side of the dimer axis. It is especially useful in Raman optical activity measurement and chiral sensing of small quantity of chiral molecule.
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35. |
- Tian, X. R., et al.
(författare)
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Multipolar Fano Resonances and Fano-Assisted Optical Activity in Silver Nanorice Heterodimers
- 2014
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Ingår i: ACS Photonics. - : American Chemical Society (ACS). - 2330-4022. ; 1:11, s. 1156-1164
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Tidskriftsartikel (refereegranskat)abstract
- We propose a simple structure of a silver nanorice heterodimer to achieve both Fano resonances and strong optical activity. Due to the ellipsoid shape of nanorice, the dinner shows a unique plasmon hybridization picture, being different from those in previously studied two-nanoparticle coupling, which benefits the generation of Fano resonances here. Under oblique incidence, this nanorice dimer exhibits not only multipolar Fano resonances but also very strong optical activity in the Fano resonant ranges. A chiral molecule model is proposed to explain the generation of chirality. It is also shown that Fano resonance has an assisting effect on optical activity (especially for subradiant modes), which can be ascribed to the energy transfer from the super-radiant modes to the subradiant modes during Fano interference.
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36. |
- Wang, H., et al.
(författare)
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Plasmon-driven surface catalysis in hybridized plasmonic gap modes
- 2014
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 4, s. Art. no. 7087-
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Tidskriftsartikel (refereegranskat)abstract
- Plasmon-driven surface catalytic (PDSC) reaction in Ag/Au nanoparticle monomer or dimer-film gaps are experimentally and theoretically investigated, using surface enhanced Raman scattering (SERS) and finite element method. The variation of SERS spectra in different nano gaps of nanoparticle-film systems indicated the PDSC reaction was largely depended on the number of nanoparticles. The higher Raman intensity of p, p'-dimercaptoazobenzene (DMAB) in dimer-film nanogap was because effective coupling of induced image charge on metal film in hybridized plasmonic gap mode, which was confirmed by the electric field distribution. Furthermore, the influence of material and wavelength was also studied to obtain the optimal experimental condition for best surface catalysis in hybridized plasmonic gap mode. Our studies in this common configuration of plasmonic nanostructure are of great significance not only in the field of catalysis on metal surface but also in other surface plasmon fields such as senor, photon detection, water splitting, etc.
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37. |
- Wang, Xi, et al.
(författare)
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Self-Constructed Multiple Plasmonic Hotspots on an Individual Fractal to Amplify Broadband Hot Electron Generation
- 2021
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 15:6, s. 10553-10564
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Tidskriftsartikel (refereegranskat)abstract
- Plasmonic nanoparticles are ideal candidates for hot-electron-assisted applications, but their narrow resonance region and limited hotspot number hindered the energy utilization of broadband solar energy. Inspired by tree branches, we designed and chemically synthesized silver fractals, which enable self-constructed hotspots and multiple plasmonic resonances, extending the broadband generation of hot electrons for better matching with the solar radiation spectrum. We directly revealed the plasmonic origin, the spatial distribution, and the decay dynamics of hot electrons on the single-particle level by using ab initio simulation, dark-field spectroscopy, pump–probe measurements, and electron energy loss spectroscopy. Our results show that fractals with acute tips and narrow gaps can support broadband resonances (400–1100 nm) and a large number of randomly distributed hotspots, which can provide unpolarized enhanced near field and promote hot electron generation. As a proof-of-concept, hot-electron-triggered dimerization of p-nitropthiophenol and hydrogen production are investigated under various irradiations, and the promoted hot electron generation on fractals was confirmed with significantly improved efficiency.
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38. |
- Zhang, X., et al.
(författare)
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Plasmon-driven sequential chemical reactions in an aqueous environment
- 2014
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Plasmon-driven sequential chemical reactions were successfully realized in an aqueous environment. In an electrochemical environment, sequential chemical reactions were driven by an applied potential and laser irradiation. Furthermore, the rate of the chemical reaction was controlled via pH, which provides indirect evidence that the hot electrons generated from plasmon decay play an important role in plasmon-driven chemical reactions. In acidic conditions, the hot electrons were captured by the abundant H+ in the aqueous environment, which prevented the chemical reaction. The developed plasmon-driven chemical reactions in an aqueous environment will significantly expand the applications of plasmon chemistry and may provide a promising avenue for green chemistry using plasmon catalysis in aqueous environments under irradiation by sunlight.
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39. |
- Zhang, Z. L., et al.
(författare)
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Propagating Surface Plasmon Polaritons: Towards Applications for Remote-Excitation Surface Catalytic Reactions
- 2016
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Ingår i: Advanced Science. - : Wiley. - 2198-3844 .- 2198-3844. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Plasmonics is a well-established field, exploiting the interaction of light and metals at the nanoscale; with the help of surface plasmon polaritons, remote-excitation can also be observed by using silver or gold plasmonic waveguides. Recently, plasmonic catalysis was established as a new exciting platform for heterogeneous catalytic reactions. Recent reports present remote-excitation surface catalytic reactions as a route to enhance the rate of chemical reactions, and offer a pathway to control surface catalytic reactions. In this review, we focus on recent advanced reports on silver plasmonic waveguide for remote-excitation surface catalytic reactions. First, the synthesis methods and characterization techniques of sivelr nanowire plasmonic waveguides are summarized, and the properties and physical mechanisms of plasmonic waveguides are presented in detail. Then, the applications of plasmonic waveguides including remote excitation fluorescence and SERS are introduced, and we focus on the field of remote-excitation surface catalytic reactions. Finally, forecasts are made for possible future applications for the remote-excitation surface catalysis by plasmonic waveguides in living cells.
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