Search results for "plasmon"
showing 10 items of 614 documents
Surface enhanced Raman scattering of silver sensitized cobalt nanoparticles in metal–dielectric nanocomposites
2008
We report the preparation of a new type of nanocomposite containing cobalt and silver nanoparticles organized in parallel layers with a well controlled separation. This arrangement allows the observation of an enhanced low-frequency Raman signal at the vibration frequency of cobalt nanoparticles excited through the surface plasmons of silver nanoparticles. Numerical simulations of the electric field confirm the emergence of hot spots when the separation between silver and cobalt nanoparticles is small enough. © IOP Publishing Ltd.
Optical determination and identification of organic shells around nanoparticles: application to silver nanoparticles
2013
We present a simple method to prove the presence of an organic shell around silver nanoparticles. This method is based on the comparison between optical extinction measurements of isolated nanoparticles and Mie calculations predicting the expected wavelength of the Localized Surface Plasmon Resonance of the nanoparticles with and without the presence of an organic layer. This method was applied to silver nanoparticles which seemed to be well protected from oxidation. Further experimental characterization via Surface Enhanced Raman Spectroscopy (SERS) measurements allowed to identify this protective shell as ethylene glycol. Combining LSPR and SERS measurements could thus give proof of both …
Asymmetrical waveguide coupling by a tilted metal nanocone
2017
Kasvava uusiutuvan energian tarve ajaa tiedeyhteisöä etsimään uusia vihreitä energian lähteitä. Osana tätä tavoitetta, WISC-projekti pyrkii yhdistämään infrapunaa keräävän aurinkopaneelin normaaliin ikkunaan. Tässä tutkimuksessa me tutkimme sisääntulevan valon kytkeytymistä kallistuneesta kultananokartiosta laattamaisen aaltojohteen ohjattuihin aaltojohdemoodeihin; tavoitteena on esittää epäsymmetristä aaltojohteeseen kytkeytymistä. Tutkimus suoritettiin simuloimalla Comsolissa käyttäen kolmiulotteista äärellisten elementtien menetelmää. Ulospäin suuntautuva aaltojohteeseen sironneen valon energiavuo mitattiin 2.1 aallonpituuden päässä nanokartiosta. Tulokset viittaavat kahden samanaikaisen…
Plasmonic Stripes in Aqueous Environment Co-Integrated With Si3N4 Photonics
2018
We demonstrate the design, fabrication, and the experimental characterization of gold-based plasmonic stripes butt-coupled with low-pressure-chemical-vapor-deposition (LPCVD)-based Si3N4 waveguides for the excitation of surface-plasmon-polariton (SPP) modes in aqueous environment. Plasmonic gold stripes, in aqueous environment, with cross-sectional dimensions of 100 nm × 7 μm were interfaced with 360 nm × 800 nm Si3N4 waveguides cladded with low-temperature-oxide, exploiting linear photonic tapers with appropriate vertical (VO) and longitudinal (LO) offsets between the plasmonic and photonic waveguide facets. An interface insertion loss of 2.3 ± 0.3 dB and a plas…
Spatial localization of hotspots in Fano-resonant plasmonic oligomers for surface-enhanced coherent anti-Stokes Raman scattering
2020
AbstractRealization of Fano resonance in plasmonic oligomers is often exploited to design efficient plasmonic substrates for surface-enhanced coherent anti-Stokes Raman scattering. Disk-type Fano-resonant plasmonic oligomers are widely used to enhance the Raman signal of the probe material. Generally, hot spots are generated in those oligomers at different spatial locations at different wavelengths and only a few spatially overlapping hot spots at multiple wavelengths can be achieved with oblique incidence of excitation light. In this work, we proposed hexagonal gold nanoparticle based Fano-resonant plasmonic oligomers that can yield higher number of spatially overlapped hot spots compared …
Fabrication-friendly polarization-sensitive plasmonic grating for optimal surface-enhanced Raman spectroscopy
2020
Plasmonic nanostructures are widely utilized in surface-enhanced Raman spectroscopy (SERS) from ultraviolet to near-infrared applications. Periodic nanoplasmonic systems such as plasmonic gratings are of great interest as SERS-active substrates due to their strong polarization dependence and ease of fabrication. In this work, we modelled a silver grating that manifests a subradiant plasmonic resonance as a dip in its reflectivity with significant near-field enhancement only for transverse-magnetic (TM) polarization of light. We investigated the role of its fill factor, commonly defined as a ratio between the width of the grating groove and the grating period, on the SERS enhancement. We des…
Interactions between silver nanoparticles and fluorescent phytochromes from Deinococcus radiodurans
2017
Poikkitieteelliset sovellukset ovat viime aikoina yleistyneet tieteellisessä tutkimuksessa. Tämä näkyy hyvin esimerkiksi elävän kudoksen kuvantamisen kehittymisessä, jota varten etsitään jatkuvasti parempia biologisia leimoja fysiikan ja kemian keinoin. Tässä tutkielmassa on kehitetty ensimmäinen lähi-infrapuna-alueen fluoresenssileima, joka hyödyntää hopeananopartikkeleja ja fytokromeja. Kompleksi on syntetisoitu itse ja sen rakenne on todennettu optisen spektroskopian, elektroforeesin ja elektronimikroskopian keinoin. Lupaavat fluoresenssiominaisuudet saatiin käyttämällä monomeerisen Deinococcus radiodurans -fytokromin kromoforia sitovaa domeenia (CBDmon). Hopeapartikkelien läsnäollessa C…
Optical biosensor-based characterization of anti-double-stranded DNA monoclonal antibodies as possible new standards for laboratory tests.
2009
The serum determination of circulating anti-double-stranded (ds)DNA autoantibodies is a routine measure for the laboratory diagnosis of systemic lupus erythematosus. Since available assays differ substantially and no feasible calibrator is available, the aim of this study was to evaluate a recently introduced surface plasmon resonance (SPR) biosensor chip for binding studies between dsDNA and anti-dsDNA autoantibodies and to demonstrate its usefulness for the characterization of new monoclonal antibody (mAb) standards and standardization of assays. We characterized two human and one murine monoclonal anti-dsDNA antibodies by measuring the kinetic on- and off-rates using the biosensor and ca…
Design of anisotropic nanostructures for light control
2018
El rápido avance en métodos de micro- y nanofabricación, tanto teórica como experimentalmente, han hecho posible a día de hoy que podamos controlar el flujo de luz con una precisión sin precedentes. Los metamateriales y las metasuperficies son nanoestructuras compuestas a partir de celdas unidad dise˜nadas, de forma que permitan manipular la luz con una respuesta estipulada. Como resultado de esto, los metamateriales han proporcinoado un gran número de posibles aplicaciones nuevas que antes eran inconcebibles. En esta Tesis Doctoral nos hemos centrado en el uso de estos metamateriales excepcionales para conseguir, específicamente, partículas indetectables y también para controlar el modelad…