Light scattering from spherical plasmonic nanoantennas: effects of nanoscale roughness

Wang, H.; Fu, Kun; Drezek, Rebekah A.; Halas, Naomi J.

doi:10.1007/s00340-006-2223-0

Cited by 51 publications

(49 citation statements)

References 21 publications

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“…This calculation indicates that out of a resonant frequency for the 2D grating (no Bragg-SPP), localized plasmon resonances can still be excited due to the metal roughness in accordance with the experimental observations. [28][29][30][31][32][33][34][35][36][37][38][39] The improved detection of these bands is attributed to the different molecular orientations of the BZT molecules placed within the randomly oriented hot spots in the roughness of the plasmonic crystal. When the structures are illuminated with a 785nm radiation, an SPP mode excited through the grating periodicity (Bragg-SPP mode) can be clearly observed in the electric field maps for the ideal and s-PC (figures 3d and 3e), but it is in the r-PC (figure 3f) where this SPP is used to excite localized resonances at the sharp edges of the rough metallic film deposited onto the nanocrystalline TiO 2 film, producing the highest value of the electric field intensity and therefore, responsible for the high Raman signal measured in the r-PCs.…”

Section: Resultsmentioning

confidence: 99%

“…[21][22][23][24] However, a top down approach to fabricate photonic structures capable of sustain abundant and intense hot spots, such as the ones produced in sharp edges and within gaps between metal features, remains a challenge. [27] Surface roughness has also been linked to differences in angular light scattering distributions of colloidal gold nanoparticles [28] and shown great potential application for SERS. The architecture of the plasmonic crystal allows one to tailor the optical response of the structure to a specific frequency (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Surface roughness boosts the SERS performance of imprinted plasmonic architectures

et al. 2016

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The large-area low-cost rough plasmonic crystal (r-PC) SERS substrates introduced herein outperform smooth counterparts and rough films both in magnitude of the Enhancement Factor (EF) and in the number of vibrational peaks displayed in the Raman spectrum. In r-PCs, photonic modes launched by the lattice excite more intense and abundant localized resonances in the sharp edges and gaps present in the rough metal surface. 2D r-PCs are fabricated by nanoimprinting a nanocrystalline titania paste followed by silver coating, resulting in a highly reproducible rough photonic architecture. The SERS performance of these architectures is tested via detection of two molecules; Benzenethiol and 4-Mercaptopyridine. The resulting EFs exceed 10 7 in the case of Benzenethiol and 10 10 when using 4-Mercaptopyridine. The simple fabrication strategy and the high performance exhibited by these nanoimprinted substrates, place rough plasmonic architectures as one of the most promising candidates for inexpensive and efficient mass-produced SERS substrates.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Surface roughness boosts the SERS performance of imprinted plasmonic architectures

et al. 2016

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“…Reorganization and reconstruction may produce small-scale roughness, in addition to any intrinsic roughness due to lattice defects and stacking faults. These defects have been directly observed by Chang et al, 2 Wang et al 25 and also by Gai and Harmer in highresolution TEM studies of electrochemically and chemically prepared gold rods. 26 Such roughness may alter the surface plasmon energy and may be as important as polydispersity or particle geometry in determining the ensemble optical properties.…”

Section: Introductionmentioning

confidence: 84%

Redshift of surface plasmon modes of small gold rods due to their atomic roughness and end-cap geometry

et al. 2008

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We use the surface integral technique for calculation of the extinction spectra of small metal particles of different shapes. We consider in detail different nonellipsoidal geometries in the electrostatic limit, including cylinders and a variety of capped cylinders. It is shown that different capping geometries have pronounced effects on the energy and intensity of the longitudinal surface plasmon mode. In addition, we propose that atomic scale surface roughness may also be an important determinant of the surface plasmon peak energy. A surface roughness of 0.10, equivalent to around two atomic layers, can generate redshifts in surface plasmon modes similar in magnitude to the redshifts induced by changes in the end-cap geometry.

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“…For example, recent studies have shown that the introduction of nanoscale texturing or the presence of defects on the nanoparticle surface can result in interesting changes to both the far-field and near-field properties of metallic nanoshells. [26,27] On macroscopic metallic surfaces or films, surface roughness and defects have long been known to relax the boundary conditions that prevent the direct excitation of surface plasmon waves. For mesoscopic particles, already in a size regime where direct optical excitation of dipole and higher-order multipole modes is possible, it is observed that the introduction of roughness onto the particle surface preferentially dampens the higher-order modes relative to those of a smooth spherical particle.…”

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confidence: 99%

Mesoscopic Au “Meatball” Particles

2008

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In this Communication we report the synthesis and optical properties of mesoscopic Au particles with a novel, highly roughened, "meatball-like" morphology, and the performance of these particles as substrates for surface-enhanced Raman spectroscopy (SERS). Sub-micrometer metallic particles of Au and Ag have unique optical properties in the visible and near infrared (NIR) regions of the spectrum that are highly useful for a variety of applications, such as nanoscale optical components or devices, [1][2][3] chemical and biomolecular sensing, [4,5] medical imaging and photothermal therapy, [6][7][8] andsurface-enhanced spectroscopies. [9][10][11] The optical properties of metallic nanoparticles are dominated by the collective oscillations of free electrons in the metal, known as surface plasmons.[12] The plasmon resonance frequencies of a metallic nanoparticle are dependent on the particle's size, shape, [13,14] and surface topography because the oscillations of free electrons are controlled by the particle geometry.For spherical Au or Ag nanoparticles much smaller than the wavelength of light, only the dipole plasmon resonance is excited. This size regime is known as the "dipole" or "quasistatic" limit, since all the electrons of the particle experience the same phase of the incident electromagnetic field.[15] As the particle size is increased, higher-order multipolar plasmon modes can also be excited, with the multipolar plasmon modes appearing at shorter wavelengths than the dipole plasmon feature in the particle's overall extinction spectrum. Since the excitation of higher-order modes occurs when the phase of the optical field varies across the spatial extent of the particle, they are also known as phase retardation effects. Phase retardation also gives rise to significant red-shifting and broadening of the dipole resonance. Higher-order multipolar plasmon modes have been theoretically predicted and experimentally observed for large Au or Ag quasispherical particles with diameters larger than 100 nm [16,17] and spherical metallic nanoshells. [18][19][20][21] For particles with reduced symmetry, or in an anisotropic dielectric environment, the nature of the multipolar plasmon modes becomes more complex. Metallic nanoparticles with nonspherical shapes, such as nanorods, [22] nanocubes, [23] triangular nanoprisms, [24] and nanopolyhedrons, [25] have also been shown to support higher-order multipolar plasmon modes.In addition to particle size and shape, the surface topography of a particle can also significantly influence its optical properties. For example, recent studies have shown that the introduction of nanoscale texturing or the presence of defects on the nanoparticle surface can result in interesting changes to both the far-field and near-field properties of metallic nanoshells. [26,27] On macroscopic metallic surfaces or films, surface roughness and defects have long been known to relax the boundary conditions that prevent the direct excitation of surface plasmon waves. For mesoscopic particles, already in a...

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Light scattering from spherical plasmonic nanoantennas: effects of nanoscale roughness

Cited by 51 publications

References 21 publications

Surface roughness boosts the SERS performance of imprinted plasmonic architectures

Surface roughness boosts the SERS performance of imprinted plasmonic architectures

Redshift of surface plasmon modes of small gold rods due to their atomic roughness and end-cap geometry

Mesoscopic Au “Meatball” Particles

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