Enhanced Fluorescence from Periodic Arrays of Silver Nanoparticles

Abstract

Electron beam lithography was used to fabricate silver nanoparticle arrays and study the effects of geometrical properties of particles on metal-enhanced fluorescence. Nanoparticle size, shape, interparticle spacing, and nominal thickness were varied in a combinatorial pattern for investigation of the particle plasmon resonance effect on enhancement of fluorescence from three different fluorophores; Fluorescein, Cy3, and Cy5. A specific geometric property for optimal enhancement from each fluorophore was determined. For interparticle spacings greater or equal to 270 nm, the enhancement matched what is expected for a single-particle model. For those particles smaller than 210 nm, the enhancement was lower than for the larger spacing in the range studied. Triangular-shaped particles gave similar enhancement to those of square-shaped particles. This combinatorial pattern by e-beam lithography was found to be useful for studying how individual parameters enhance the fluorescence that are important for rational design of enhanced fluorescence sensors.

Enhanced localized fluorescence in plasmonic nanoantennae

“…LSPRs can generate high, localized electromagnetic fields which entice scientists and engineers for a variety of achieved and future applications. These include Raman scattering, 3,4 single molecule fluorescence, 5,6 enhanced emission from dyes and quantum dots ͑QDs͒, [7][8][9][10][11][12][13][14][15] various nonlinear optical processes, [16][17][18] and the basis for a subwavelength sized nanolaser. [19][20][21] The nanoantenna ͑also known as an optical antenna͒ system consisting of single or coupled nanoparticles, either isolated or arrayed, is well studied.…”

“…[19][20][21] The nanoantenna ͑also known as an optical antenna͒ system consisting of single or coupled nanoparticles, either isolated or arrayed, is well studied. [5][6][7][8][9][10][11][12][13][14][15][22][23][24][25][26][27][28][29] The system of two closely spaced nanoparticles is of particular interest as the LSPR of individual particles couple, resulting in greater electric field enhancement [24][25][26] and a systematic red shift compared to a single particle. [22][23][24]28 Field enhancements afforded by LSPRs result in enhanced emission of dyes and QDs in the vicinity of the nanoparticles.…”

“…[5][6][7][8][9][10][11][12][13][14][15] Briefly, the source of the enhancement is twofold: feedback between the emitter and the resonant nanoparticles increases the emitter's radiative decay rate so the photon emission rate increases and the nanoantenna system acts as a transducer for light from the near field to the far field. [8][9][10][11][12][13]15 Studying the interactions of a nanoantenna with localized, nanosized emitters makes a strong starting point for the development of LSPR-based lighting devices with properties such as high spatial localization of a usable light source and efficiency improvements for light extraction from emitters, including QDs and carbon nanotubes ͑CNTs͒. [5][6][7][8][9][10][11][12][13][14][15]27,30 It is postulated that laserlike light can coherently emit from a nanoantenna system coupled to a localized gain medium.…”

“…[8][9][10][11][12][13]15 Studying the interactions of a nanoantenna with localized, nanosized emitters makes a strong starting point for the development of LSPR-based lighting devices with properties such as high spatial localization of a usable light source and efficiency improvements for light extraction from emitters, including QDs and carbon nanotubes ͑CNTs͒. [5][6][7][8][9][10][11][12][13][14][15]27,30 It is postulated that laserlike light can coherently emit from a nanoantenna system coupled to a localized gain medium. Such a nanolaser is theoretically possible if the gain factor from the emitter can overcome losses and coherent, near-field feedback is established between the nanoantenna and the gain medium.…”

Modulação de fluorescência de amino coumarinas e acridinas por nanopartículas de prata

“…Neste caso, um efeito similar tem sido observado para as intensidades de fluorescência de fluoróforos orgânicos adsorvidos sobre superfícies contendo nanopartículas ou filmes finos de metais como ouro e prata [7,16]. A presença de nanopartículas metálicas nestes sistemas pode influenciar as propriedades fotofísicas dos fluoróforos, ou seja, influenciar a taxa radiativa dos mesmos, aumentando ou diminuindo-a, dependendo da sua distância em relação ao fluoróforo [3,10]. Este efeito provocado pela superfície metálica é denominado de efeito de ressonância de plasmon.…”