Optical properties of self-affine thin films

Shalaev, Vladimir M.; Botet, Robert; Mercer, Jerry W.; Stechel, Ellen B.

doi:10.1103/physrevb.54.8235

Cited by 59 publications

(49 citation statements)

References 24 publications

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“…The "rst computer [15,36}38,40}45,47] and experimental results [39,46,58] for the "eld distribution in percolation composites show that the local "eld distributions contain sharp peaks with distances between them much larger than the metal grain size. This pattern agrees qualitatively with numerical calculations and experimental results for metal fractals [25,27,59,60] and self-a$ne "lms [28]. Therefore, the local electric "eld by no means can be considered as the same in all metal grains of the composite.…”

Section: Introductionsupporting

confidence: 79%

“…The localized and strongly #uctuating local "elds in fractals were imaged by means of the near-"eld scanning optical microscopy (NSOM) in [27]. Similar pattern for the "eld distribution was obtained for self-a$ne thin "lms [28] that have fractal structure of the surface, with di!erent scaling properties in the plane of the "lm and normal to it.…”

Section: Introductionmentioning

confidence: 89%

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Electromagnetic field fluctuations and optical nonlinearities in metal-dielectric composites

2000

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Section: Introductionsupporting

confidence: 79%

Section: Introductionmentioning

confidence: 89%

Electromagnetic field fluctuations and optical nonlinearities in metal-dielectric composites

2000

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“…26 If the nanoparticles are aggregated, it is thought that intense electric field coupling in ''hot spot'' regions between adjacent nanoparticles can engender higher enhancement. 27,28 An intrinsic advantage of the self-assembled nanoparticle films is their high surface area available for analyte adsorption. The fabrication of such substrates, however, requires the design of wet-assembly techniques that are controllable, precise and reproducible, which has proven to be an overarching problem in most nanoparticle assembly processes.…”

Section: Orlin Velevmentioning

confidence: 99%

Controlled assembly of SERS substrates templated by colloidal crystal films

2006

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Convective assembly at high volume fractions was used to assemble gold nanoparticles into structured porous films templated by colloidal crystals. These gold nanofilms have hierarchical porosity and were proven to be stable and efficient substrates for surface-enhanced Raman spectroscopy (SERS). The control over the film structure allowed optimization of their performance for potential sensor applications.Colloidal crystals are materials with periodic structure on the submicrometre length scale made by self-assembly of colloidal particles. Colloidal crystals can be used as a basis for fabrication of photonic materials, 1-7 optical coatings and filters, [8][9][10] lithographic etching masks, 11-13 and sensors. 14-17 The colloidal crystals can also serve as templates for a variety of other self-assembled materials with controlled and reproducible structure. In this review we highlight results based on our process for rapid and reproducible deposition of colloidal crystal films by convective assembly at high volume fractions. 18These crystal films serve as templates of controlled structure for surface-enhanced Raman spectroscopy substrates. 16,19The hallmark of SERS is selectivity, potential for remote sampling through fiber optics, and capability for detection of analytes in aqueous solvents. Despite these advantages the widespread use of SERS-based analytical technology has been slow. Before SERS-based sensors can find broad application in routine chemical analysis new SERS materials must be developed that yield consistently high signals and provide detection generality towards a wide range of chemical and environmental analytes. The major requirements for the SERS substrate materials include controlled nanoscale structure, periodicity and chemical stability. One of the well-studied methods for making SERS substrates uses mono-and bi-layers of close-packed microsphere

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“…8,23 This, however, is not entirely surprising, given the differences in the type of SERS substrates being considered. In fact, the typical SERS spectroscopy enhancement factors are fairly similar to those found in this work.…”

Section: Discussionmentioning

confidence: 99%

Near-field electromagnetic wave scattering from random self-affine fractal metal surfaces: Spectral dependence of local field enhancements and their statistics in connection with surface-enhanced Raman scattering

Sánchez‐Gil

Garcı́a-Ramos

Mendez³

2000

Phys. Rev. B

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By means of rigorous numerical simulation calculations based on the Green's theorem integral equation formulation, we study the near EM field in the vicinity of very rough, one-dimensional self-affine fractal surfaces of Ag, Au, and Cu (for both vacuum and water propagating media) illuminated by a p polarized field. Strongly localized enhanced optical excitations (hot spots) are found, with electric field intensity enhancements of close to 4 orders of magnitude the incident one, and widths below a tenth of the incoming wavelength. These effects are produced by roughness-induced surface-plasmon polariton excitation. We study the characteristics of these optical excitations as well as other properties of the surface electromagnetic field, such as its statistics (probability density function, average and fluctuations), and their dependence on the excitation spectrum (in the visible and near infrared). Our study is relevant to the use of such self-affine fractals as surface-enhanced Raman scattering substrates, where large local and average field enhancements are desired.

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Optical properties of self-affine thin films

Cited by 59 publications

References 24 publications

Electromagnetic field fluctuations and optical nonlinearities in metal-dielectric composites

Electromagnetic field fluctuations and optical nonlinearities in metal-dielectric composites

Controlled assembly of SERS substrates templated by colloidal crystal films

Near-field electromagnetic wave scattering from random self-affine fractal metal surfaces: Spectral dependence of local field enhancements and their statistics in connection with surface-enhanced Raman scattering

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