Search results for "PLASMON RESONANCE"
showing 10 items of 212 documents
Controlling the oxidation processes of Zn nanoparticles produced by pulsed laser ablation in aqueous solution
2016
We used online UV-VIS optical absorption and photoluminescence spectra, acquired during and after pulsed laser ablation of a Zinc plate in aqueous solution, to investigate the effect of the laser repetition rate and liquid environment on the oxidation processes of the produced nanoparticles. A transient Zn/ZnO core-shell structure was revealed by the coexistence of an absorption peak around 5.0 eV due to Zn surface plasmon resonance and of an edge at 3.4 eV coming from wurtzite ZnO. The growth kinetics of ZnO at the various repetition rates, selectively probed by the excitonic emission at 3.3 eV, began immediately at the onset of laser ablation and was largely independent of the repetition …
Oxidation of Zn nanoparticles probed by online optical spectroscopy during nanosecond pulsed laser ablation of a Zn plate in H2O
2015
We report online UV-Visible absorption and photoluminescence measurements carried out during and after pulsed laser ablation of a zinc plate in water, which clarify the events leading to the generation of ZnO nanoparticles. A transient Zn/ZnO core-shell structure is revealed by the coexistence of the resonance absorption peak around 5.0 eV due to Zn surface plasmon resonance and the edge at 3.5 eV of ZnO. The growth kinetics of ZnO, selectively probed by the exciton luminescence at 3.3 eV, begins only after a ∼30 s delay from the onset of laser ablation. We also detect the luminescence at 2.3 eV of ZnO oxygen vacancies, yet rising with an even longer delay (∼100 s). These results show that …
Plasmonic photoluminescence enhancement by silver nanowires
2015
Strong enhancement of photoluminescence is demonstrated for CdS nanocrystals and ruthenium-based dye (N719) due to localized surface plasmon resonance of silver nanowires placed on silver film. Alternative reasons for photoluminescence modulation such as mirror effect and uneven coating by dye or nanocrystals due to geometrical factors are discussed. An artifact such as carbon contamination at the surface of silver nanowires at high laser power is demonstrated and taken into consideration. Silver nanowire on silver film is proved to be an effective system for photoluminescence enhancement by localized surface plasmon resonance.
Plasmon-induced slow aging of exciton generation and dissociation for stable organic solar cells
2016
Fast degradation is a major issue with organic photovoltaics (OPVs). Integrating plasmonics with OPVs has improved their efficiency; however, the stability effects are unknown. We demonstrate that plasmonic effects can improve the lifetime and efficiency. The aging effects on charge carrier generation and transport are investigated. Confocal time-resolved photoluminescence of Au nanoparticle (NP) doped polymer blend was performed to understand the plasmonic effects on excited-state dynamics. Hot exciton generation is observed directly at the Au-NP surface, which contributed to achieving a nearly perfect exciton dissociation yield. We found that slow aging of the plasmonic effect and the hot…
Nanoassembled plasmonic-photonic hybrid cavity for tailored light-matter coupling.
2010
We propose and demonstrate a hybrid cavity system in which metal nanoparticles are evanescently coupled to a dielectric photonic crystal cavity using a nanoassembly method. While the metal constituents lead to strongly localized fields, optical feedback is provided by the surrounding photonic crystal structure. The combined effect of plasmonic field enhancement and high quality factor (Q approximately 900) opens new routes for the control of light-matter interaction at the nanoscale.
Plasmonic nanostructures for light trapping in thin-film solar cells
2019
M.J.M. acknowledges funding from FCT through the grant SFRH/BPD/115566/2016. ALTALUZ (Reference PTDC/CTM-ENE/5125/2014). The optical properties of localized surface plasmon resonances (LSPR) sustained by self-assembled silver nanoparticles are of great interest for enhancing light trapping in thin film photovoltaics. First, we report on a systematic investigation of the structural and the optical properties of silver nanostructures fabricated by a solid-state dewetting process on various substrates. Our study allows to identify fabrication conditions in which circular, uniformly spaced nanoparticles are obtainable. The optimized NPs are then integrated into plasmonic back reflector (PBR) st…
Surface Plasmon Platform for Angle-Resolved Chiral Sensing
2019
Chiral sensitive techniques have been used to probe the fundamental symmetries of the universe, study biomolecular structures, and even develop safe drugs. As chiral signals are inherently weak and...
Influence of an Electron Beam Exposure on the Surface Plasmon Resonance of Gold Nanoparticles
2013
Electron beam imaging is a common technique used for characterizing the morphology of plasmonic nanostructures. During the imaging process, the electron beam interacts with traces of organic material in the chamber and produces a well-know layer of amorphous carbon over the specimen under investigation. In this paper, we investigate the effect of this carbon adsorbate on the spectral position of the surface plasmon in individual gold nanoparticles as a function of electron exposure dose. We find an optimum dose for which the plasmonic response of the nanoparticle is not affected by the imaging process. The final publication is available at link.springer.com
Optical response and shapes of charged sodium clusters; an analogue of the nuclear giant dipole response
1995
Collective vibrations of de-localized electrons against the positive charged ionic background in sodium clusters (plasmon resonances) and the collective vibrations of protons against neutrons in nuclei (giant dipole resonances) have several features in common. However, fundamental differences exist due to differences in the two media; the nucleus is a quantum liquid whereas the metallic medium is more like a plasma with classical positive ions and quantized electrons. The similarities and differences are illustrated by results from optical response measurements for charged sodium clusters with 14 to 48 atoms.
Many-body origin of the plasmon resonance in small metal clusters
1994
The origin of the plasmon excitation in small metal clusters is studied within the jellium model through ab initio electronic-structure calculations based on the nuclear shell model. In the limit of infinite size, the plasmon classically represents pure harmonic motion of the center of mass of the valence electrons. It is shown that this limit is already well approximated by clusters of only eight electrons.