Tunable Localized Plasmon Transducers Prepared by Thermal Dewetting of Percolated Evaporated Gold Films

Abstract

Gold island films displaying localized plasmon properties were prepared by evaporation of just-percolated Au films onto glass substrates followed by annealing at g550 °C. Annealing induces depercolation and formation of large, singlecrystalline, well-separated islands, partially embedded in the glass. Two dewetting mechanisms were identified, depending on the initial film morphology. The variability of island sizes and shapes provides effective means of tuning the position of the localized surface plasmon resonance (LSPR) band in a wide wavelength range. With an increase in the Au nominal thickness a transition occurs from transducers dominated by absorbance to ones dominated by scattering. Numerical simulations taking into account the shape and size distribution in actual island samples are in agreement with the experimental spectra. Refractive index sensitivity (RIS) measurements at a constant wavelength or at a constant extinction, tailored to the specific transducer, provide superior sensitivity to refractive index change, up to ca. 600 nm RIU À1 in wavelength shift.

RETRACTED: Investigation of plasmonic studies on morphology of deposited silver thin films having different thicknesses by soft computing methodologies—A comparative study

“…Some distinct holes appear on the surface at this temperature (Fig. 2), indicating partial embedding of Ag particles in the substrate during high temperature annealing as reported in past studies [4,10]. For this work, thermal annealing is carried out at 250 1C since smallest diameters corresponding to 5 nm can be obtained, and hence confirm this as the most appropriate temperature to transform Ag thin films to Ag particles.…”

“…These characteristics are due to time-varying electric fields exerting a force on the gas of electrons inside a metal, with consequent charge density oscillations, known as localized surface plasmons (LSP), confined to the metal [1,2]. When light, as a particular case of an electric field, is incident on these MNPs at a wavelength where resonance occurs, a resulting strong light scattering and absorption can be perceived by the appearance of an intense surface plasmon (SP) absorption band [3,4]. This SP band can be shifted by numerous factors such as type of material, size, shape, inter-particle distance, particle density, and dielectric materials.…”

Ultrasmooth, Highly Spherical Monocrystalline Gold Particles for Precision Plasmonics

“…An alternative is heterogeneous growth on a spherical dielectric shell, which produces nanoshells 26 that are spherical but polycrystalline, and as a result have rough surfaces and grain boundaries that can lead to additional losses in plasmonic applications. Nanoshells are also subject to dewetting 27 and thermal instabilities. 28 Our solution to this quandary is to use both growth and etching, rather than simply adjusting the growth conditions, to make solid gold nanospheres (Figure 1a).…”

Nanoplasmonic Sensing using Metal Nanoparticles

“…The correlation between the plasmon peak position and the bulk RI sensitivity has been verified experimentally by several groups including ours. [147][148][149] In Paper IV, the RI sensitivity was investigated for a large variety of gold nanoparticles with different plasmon frequencies, obtaining a clearly linear relationship between the plasmon peak resonance position and the bulk RI sensitivity ( Figure 5.4). However, it is important to notice that this correlation only is valid for dispersed nanoparticles in solution.…”