Surface Plasmon Resonances of Free-Standing Gold Nanowires Fabricated by Nanoskiving (original) (raw)
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Journal of Nanophotonics
Highly homogeneous arrays of Ag, Au and Cu nanorods were fabricated on glass substrates using electron-beam lithography and lift-off techniques. Optical properties of the fabricated structures related to localized surface plasmons (LSP), and their dependencies on the nanorod size were studied experimentally by optical extinction spectroscopy. Spectral tuning of LSP resonant scattering bands in a wide spectral range, from visible to near-infrared wavelengths, can be accomplished by tailoring of the nanorod dimensions, aspect ratios, and heights. The observed results qualitatively agree with Gans theory and numerical modeling by finite-difference time-domain technique.
Noble Metal Nanowires: From Plasmon Waveguides to Passive and Active Devices
Accounts of Chemical Research, 2012
U sing chemical synthesis, researchers can produce noble metal nanowires with highly regular, crystalline properties unachievable by alternative, top-down nanofabrication methods. Sitting at the intersection of nanochemistry and nanooptics, noble metal nanowires have generated intense and growing research interest. These nanostructures combine subwavelength transverse dimensions (50À100 nm) and longitudinal dimensions that can reach tens of micrometers or more, which makes them an ideal platform to launch surface plasmon waves by direct illumination of one end of the structure. Because of this property, researchers are using noble metal nanowires as a tool for fundamental studies of subwavelength plasmon-based optics and the properties of surface plasmon guided wave propagation in highly confined geometries below the classical optical diffraction limit. In this Account, we review some of the recent developments in plasmonic nanowire fabrication, nanowire plasmon imaging, and nanowire optical components and devices.
Micro/Nanoscale Patterning of Nanostructured Metal Substrates for Plasmonic Applications
ACS …, 2009
The ability to precisely control the pattern of different metals at the micro-and nanoscale, along with their topology, has been demonstrated to be essential for many applications, ranging from material science to biomedical devices, electronics, and photonics. In this work, we show a novel approach, based on a combination of lithographic techniques and galvanic displacement reactions, to fabricate micro-and nanoscale patterns of different metals, with highly controlled surface roughness, onto a number of suitable substrates. We demonstrate the possibility to exploit such metal films to achieve significant fluorescence enhancement of nearby fluorophores, while maintaining accurate spatial control of the process, from submicron resolution to centimeter-sized features.
Sensors, 2014
The new revolution in materials science is being driven by our ability to manipulate matter at the molecular level to create structures with novel functions and properties. The aim of this paper is to explore new strategies to obtain plasmonic metal nanostructures through the combination of a top down method, that is electron beam lithography, and a bottom up technique, that is the chemical electroless deposition. This technique allows a tight control over the shape and size of bi-and three-dimensional metal patterns at the nano scale. The resulting nanostructures can be used as constituents of Surface Enhanced Raman Spectroscopy (SERS) substrates, where the electromagnetic field is strongly amplified. Our results indicate that, in electroless growth, high quality metal nanostructures with sizes below 50 nm may be easily obtained. These findings were explained within the framework of a diffusion limited aggregation (DLA) model, that is a simulation model that makes it possible to decipher, at an atomic level, the rules governing the evolution of the growth front; moreover, we give a description of the physical
The Journal of Physical Chemistry C, 2014
Since its discovery, surface-enhanced Raman spectroscopy (SERS) has pushed researchers' interest to develop different kinds of active substrates for high sensitivity molecular detection. Defocused ion beam sputtering (IBS) represents a viable route for the production of large scale, highly reproducible SERS-active substrates consisting of near-field coupled nanowires featuring localized surface plasmon resonances in the visible and the near-infrared. Here we investigate the field enhancement and spatial confinement in the visible and the near-infrared of arrays of optically resonant gold nanowires, using two complementary techniques: SERS and scanning near-field optical microscopy (SNOM). While SERS allows us to quantify the field enhancement factor, SNOM is used to image the localization of the enhanced electromagnetic fields. We show that in the visible (633 nm) the nanowires are SERS active only for excitation polarized parallel to the wire-to-wire nanocavities, yielding enhancement factors of 7 × 10 3 . In the near-infrared (785 nm) we observe a 2-fold larger SERS enhancement (1.3 × 10 4 ) for excitation parallel to the nanocavities and detect the onset of SERS amplification for excitation polarization parallel to the nanowires long axis. Polarization-sensitive SNOM in the near-infrared (830 nm) enables the correlation of the scattered intensity with the sample morphology at the local scale. We demonstrate that the field enhancement stems from the wire-to-wire nanocavity regions when the excitation field is polarized parallel to the wire-to-wire nanocavity, while we observe more complex field confinement patterns related to the partially inhomogeneous morphology of the substrate when the polarization is parallel to the nanowires long axis. Our experiments strongly suggest IBS-fabricated nanowires as novel substrates for plasmon-enhanced spectroscopies.
Chemical Physics Letters, 2006
The SERS efficiency of gold nanowires arrays elaborated by electron beam lithography and lift-off technique efficiency is investigated by depositing a molecular probe (BPE) trans-1,2-bis(4-pyridyl)ethylen on the arrays and using an excitation wavelength of 632.8 nm. The observation of the dependence of the Raman enhancement versus the nanowire length is clearly demonstrated and remarkably a maximum enhancement is observed. For such arrays, we also show clearly that odd multipolar localised surface plasmon modes (up to seventh-order) exhibits a stronger efficiency than the first dipolar order in SERS process.
Enhancing the properties of plasmonic nanowires
Materials Research Express
In this paper, we show the approach to enhance the optical properties of the plasmonic nanowires from the perspectives of both field enhancement and tunability. Two different cases have been suggested for the consideration: the first one uses hollow-core metamaterial interface, while the other involves metallic nanowire metamaterial interface. It has been outlined, that the use of nanowire metamaterial interface allows for stretching the frequency range of surface wave existence from 500 THz (600 nm) to approximately 1000 THz (300 nm). Moreover, the nanowire metamaterial interface demonstrates better field confinement.