Effects of dimension on optical transmittance of semicontinuous gold films

Dvoynenko, Mykhailo M.; Goncharenko, Anatoliy V.; Romaniuk, V.R.; Venger, É. F.

doi:10.1016/s0921-4526(00)00759-6

Cited by 13 publications

(7 citation statements)

References 30 publications

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“…Usually, to describe the effect of the substrate on IR spectra of metal nanoparticles, a rough approximation of the effective dielectric constant ε eff = ( n S 2 + n Air 2 )/2 is assumed , as embedding the particle completely ( n S and n Air are the refractive indices of the substrate and air). Figure shows that the substrate influence of the free-standing nanoantennas on the silicon substrate is similar to the influence of a CaF 2 substrate on antennas lying directly on the substrate, which means that the effective refractive index in both cases is very similar.…”

Section: Resultsmentioning

confidence: 99%

Gold Nanoantennas on a Pedestal for Plasmonic Enhancement in the Infrared

et al. 2015

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The coupling of an infrared plasmon-polariton excitation of a metal nanoparticle to a vibrational excitation of a similar energy enables strong vibrational signal enhancement. However, the commonly used planar substrates substantially weaken plasmonic resonances because of their polarizability, and, furthermore, a great part of the enhanced near-field is inside the substrate and thus not available for an analyte. In this contribution we report on a way to reduce these undesirable influences of the substrate by fabricating gold nanowires on high pedestals and thus in reduced contact with the substrate. The influence of the height of the pedestal is an important parameter for the plasmonic near-field enhancement, as we show with finitedifference time-domain simulations. Comparing the plasmonic response and the SEIRA activity of the rods prepared by standard electron beam lithography and the rods additionally treated with reactive ion etching to remove the silicon substrate at the hot-spots of the rods reveals not only the change of the plasmonic-resonance spectrum but also interesting differences of the enhanced phonon-polariton signal from the silicon dioxide layer on the silicon substrate and the about 1 order of magnitude stronger vibrational signal enhancement for an adsorbate monolayer.

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Section: Resultsmentioning

confidence: 99%

Gold Nanoantennas on a Pedestal for Plasmonic Enhancement in the Infrared

et al. 2015

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“…Surface plasmons on patterned Au films should produce intensity decay lengths of β SP -1 = 90 nm (using (λ/4π)[(ε Au + ε w )/−ε w 2 ] 0.5 ) for continuous films with bulk Au properties . However, the effective optical properties of sub-20-nm Au films 29 are not well established from either measurements or models, particularly because such films are often discontinuous with preparation-dependent properties. Electrical conductivities of the Au films in this work, which are also used as electrodes for electrophoretic deposition, suggest that the films are beyond their percolation threshold but do not provide information on the film microstructure.…”

Section: Resultsmentioning

confidence: 99%

Mapping Patterned Potential Energy Landscapes with Diffusing Colloidal Probes

Everett

Anekal

et al. 2006

Langmuir

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We report a new method for mapping patterned surfaces based on monitoring the interactions of freely diffusing colloidal probes with pattern features to generate measured potential energy landscapes. Evanescent wave scattering and video microscopy are used to track 3D center positions of nominal 2 microm silica colloids as they diffuse over 5-20-nm-thick patterned gold films. An analysis of ensemble-averaged particle height histograms on different pattern features using Boltzmann's equation produces local electrostatic and van der Waals potentials in good agreement with independent measurements and predictions. Absolute separation is obtained from theoretical fits to measured potential-energy profiles and direct measurement by depositing silica colloids onto gold surfaces via electrophoretic deposition. As colloidal probe and pattern feature dimensions become comparable, potential energy profiles suffer some distortion due to the increased probability of probes sampling pattern feature edges. An analysis of interfacial colloidal probe diffusion in conjunction with potential energy measurements demonstrates a consistent interpretation of dissipative and conservative forces in these measurements. Future extensions of this work should produce similar approaches for interrogating physical, chemical, and biomolecular heterogeneous/patterned surfaces and structures with diffusing colloidal probes.

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“…This model is known as a good approximation for metal films, that consist of one layer of metal particles with similar shape in a random arrangement [29,30]. In Eq.…”

Section: General Remarks and Co Spectramentioning

confidence: 99%

IR spectroscopy of adsorbates on ultrathin metal films

Pucci

2005

Physica Status Solidi (b)

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Metal films with thickness in the nanometer range are optically transparent. With IR transmittance spectroscopy the in-plane film conductivity with its correlation to the film-growth process can be studied without electrical contacts and, on metal-island films, adsorbate vibrations can be observed because of surface enhanced IR absorption (SEIRA). Their analysis enables insight into the adsorbate-metal bonding and therefore gives information on the available adsorption sites and the crystalline facets correlated to. As in IR reflection absorption spectra dipole -dipole interaction of molecules on different sites modifies the vibration lines according to the degree of disorder ("atomic roughness"). Depending on that roughness IR spectra of adsorbate vibrations may be further modified because of their interaction with electronic excitations of the film. So, the limited facet size on cold-condensed metal films leads to additional IR activity: Raman lines of certain centrosymmetric adsorbate molecules (C 2 H 4 ) are observed.

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Effects of dimension on optical transmittance of semicontinuous gold films

Cited by 13 publications

References 30 publications

Gold Nanoantennas on a Pedestal for Plasmonic Enhancement in the Infrared

Gold Nanoantennas on a Pedestal for Plasmonic Enhancement in the Infrared

Mapping Patterned Potential Energy Landscapes with Diffusing Colloidal Probes

IR spectroscopy of adsorbates on ultrathin metal films

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