Template-Synthesized Nanoscopic Gold Particles: Optical Spectra and the Effects of Particle Size and Shape

Foss, Colby A.; Hornyak, Gabor L.; Stockert, Jon A.; Martin, Charles R.

doi:10.1021/j100062a037

Cited by 519 publications

(454 citation statements)

References 3 publications

(5 reference statements)

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“…oscillation of randomly orientated nanorods predicted by Gans' theory is in agreement with the results of Martin and coworkers, 9,[23][24][25][26] who also find a blue-shift of the plasmon maximum using Maxwell-Garnett theory. On the other hand, the absorption maximum of the longitudinal mode red-shifts with increasing gold nanorod aspect ratio.…”

Section: Resultssupporting

confidence: 90%

Simulation of the Optical Absorption Spectra of Gold Nanorods as a Function of Their Aspect Ratio and the Effect of the Medium Dielectric Constant

1999

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Gold nanorods with different aspect ratios are prepared in micelles by the electrochemical method and their absorption spectra are modeled by theory. Experimentally, a linear relationship is found between the absorption maximum of the longitudinal plasmon resonance and the mean aspect ratio as determined from TEM. It is shown here that such a linear dependence is also predicted theoretically. However, calculations also show that the absorption maximum of the longitudinal plasmon resonance depends on the medium dielectric constant in a linear fashion for a fixed aspect ratio. Attempts to fit the calculations to the experimental values indicate that the medium dielectric constant has to vary with the aspect ratio in a nonlinear way. Chemically, this suggests that the structure of the micelle capping the gold nanorods is size dependent. Furthermore, comparison with the results obtained for rods of different aspect ratios made by systematic thermal decomposition of the long rods further suggests that the medium dielectric constant is also temperature dependent. This is attributed to thermal annealing of the structure of the micelles around the nanorods.

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Section: Resultssupporting

confidence: 90%

Simulation of the Optical Absorption Spectra of Gold Nanorods as a Function of Their Aspect Ratio and the Effect of the Medium Dielectric Constant

1999

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“…A similar dependence was seen in silica glasses dispersed with Au colloid particles (112,113). Foss et al (68) found significant transparency in the near-IR region and strong extinction in the visible for particles with nearsphere like shape. The wavelength of maximum extinction increased with increasing particle radius, giving rise to colour variations (red-purple for 30 nm size and blue-green for 60 nm size).…”

Section: Effects Of Nanoparticle Sizesupporting

confidence: 55%

“…As the aspect ratio increases (with constant diameter), the extinction intensity increases and the extinction maxima wavelength is blue-shifted to shorter wavelengths (68). By varying the aspect ratio, systematic shifts in the extinction maxima can be attained.…”

Section: Effects Of Nanoparticle Shapementioning

confidence: 99%

“…Hornyak et al (69) prepared Au nanoparticles in nanoporous alumina membranes, and absorption properties for nanoparticles of size 52 nm down to 16 nm, and with various aspect ratios. They used a modified form of MG theory, called the dynamic MG (DMG) theory (68), to model the optical properties. They found that as the nanoparticle size decreased, the wavelength of the maximum absorption intensity max approached the value predicted by DMG theory.…”

Section: Effects Of Nanoparticle Sizementioning

confidence: 99%

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The third order nonlinear optical properties of gold nanoparticles in glasses, part II

2003

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The optical properties of gold nanoparticles have been known for a number of years and recent advances in laser power have now allowed the non-linear optical properties to be studied. In this short review paper, the various theories that have been used to describe the optical properties of gold nanoparticles are presented. Methods of preparing gold nanoparticles in glasses are explained briefly, as well as characterization techniques. The optical properties of gold nanoparticles are reviewed, as well as the effects of particle size, shape, concentration and c. Effects Of Nanoparticle SizeThe relationship between optical properties and nanoparticle radius has been studied in glasses with dispersed colloid Au nanoparticles (111,112). The peak plasmon wavelength shifts continuously to longer wavelengths with increasing average particle radius. A similar dependence was seen in silica glasses dispersed with Au colloid particles (112,113). Foss et al. (68) found significant transparency in the near-IR region and strong extinction in the visible for particles with nearsphere like shape. The wavelength of maximum extinction increased with increasing particle radius, giving rise to colour variations (red-purple for 30 nm size and blue-green for 60 nm size). This is shown in Figure 1. This was consistent with the findings of Mie (17). Hosoya et al. (73) and Muto et al. (102) found in Au:Al2O3 thin films that the spectra broadened and the peak shifted to longer wavelengths as the particle size decreased. Muto et al. (102) explained it as due to charge transfer from the metal particles to the amorphous oxide by the aluminium-metal bonds used in adhesion. The decreased electron density of the metal particles gives rise to the blue-shift. This behaviour was opposite to that of Au:SiO2, and indicates that the matrix has an effect on the blue-or red-shift of the plasmon peak with size.As the wavelength of the surface plasmon resonance changes with particle size, the χ (3) is also expected to change with size. Fukumi et al. (60), found χ (3) to be approximately proportional to the fourth power of the particle radius. They also found that χm (3) (of the metal particles on their own) had negligible dependence on the particle radius. The value of χm (3) = 2.5 x 10 -8 esu agreed with that of Hache et al. (32) and Bloemer et al. (114). Hornyak et al. (69) prepared Au nanoparticles in nanoporous alumina membranes, and absorption properties for nanoparticles of size 52 nm down to 16 nm, and with various aspect ratios. They used a modified form of MG theory, called the dynamic MG (DMG) theory (68), to model the optical properties. They found that as the nanoparticle size decreased, the wavelength of the maximum absorption intensity max approached the value predicted by DMG theory. For the smallest diameter particles, (16 nm), the values were identical with DMG theory, and they suggested that there was a quasi-static DMG limit ( max does not change from ~5 08 nm) for nanoparticles of diameter 16 nm. Alvarez et al. (115) pr...

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“…Electrodeposition of gold particles within the pores of porous alumina membranes represents attempts at reaching this aim by the electrodeposition technique. [20][21][22][23] Electrodeposition has also been used for synthesis of metal nanocrystallites on carbon based substrates such as highly oriented pyrolytic graphite (HOPG). [24][25][26] Finot et al have reported synthesis of gold nanocrystals by applying a potential step to GC as the substrate for a specific time (5 s) using dilute solutions of KAuCl 4 (1.0 × 10 -5 -2.0 × 10 -4 M) in H 2 SO 4 (0.5 M) and applying different overpotentials to investigate the effect of concentrations and potential on particle size.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Deposition of Gold Nanoparticles on Pencil Graphite by Fast Scan Cyclic Voltammetry

Etesami

Karoonian

Mohamed

2011

J Chinese Chemical Soc

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Gold nanoparticles (AuNPs) were electrodeposited on the surface of pencil graphite (PG) by fast scan cyclic voltammetry without using any additives in acidic medium. The effect of deposition time on the size of electrodeposited AuNPs was investigated in sulfuric acid as a supporting electrolyte. The deposition time was varied by varying the scan rate, number of cycles and applied potential range. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used for characterization of PG and electrodeposited AuNPs. The results confirmed that nanosized gold particles (20 ± 8 nm) were deposited on the PG substrate with almost spherical geometry.

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Template-Synthesized Nanoscopic Gold Particles: Optical Spectra and the Effects of Particle Size and Shape

Cited by 519 publications

References 3 publications

Simulation of the Optical Absorption Spectra of Gold Nanorods as a Function of Their Aspect Ratio and the Effect of the Medium Dielectric Constant

Simulation of the Optical Absorption Spectra of Gold Nanorods as a Function of Their Aspect Ratio and the Effect of the Medium Dielectric Constant

The third order nonlinear optical properties of gold nanoparticles in glasses, part II

Electrochemical Deposition of Gold Nanoparticles on Pencil Graphite by Fast Scan Cyclic Voltammetry

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