scholarly journals Quantitative morphometric analysis of single gold nanoparticles by optical extinction microscopy: Material permittivity and surface damping effects

2021 ◽  
Vol 154 (4) ◽  
pp. 044702
Author(s):  
Lukas M. Payne ◽  
Francesco Masia ◽  
Attilio Zilli ◽  
Wiebke Albrecht ◽  
Paola Borri ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Morphometric Analysis ◽  
Optical Extinction ◽  
Damping Effects

scholarly journals Continuous tuning of the plasmon resonance frequency of porous gold nanoparticles by mixed oxide layers

2020 ◽  
Vol 27 (6) ◽  
pp. 1583-1588
Author(s):  
Laura Juhász ◽  
Bence Parditka ◽  
Péter Petrik ◽  
Csaba Cserháti ◽  
Zoltán Erdélyi
Keyword(s):  
Gold Nanoparticles ◽  
Resonance Frequency ◽  
Mixed Oxide ◽  
High Surface ◽  
Volume Ratio ◽  
Mixture Ratio ◽  
Optical Extinction ◽  
Oxide Layers ◽  
Porous Gold ◽  
Wide Range

Abstract Porous gold nanoparticles (PGNs) are very popular due to their high surface/volume ratio, moreover they have stronger plasmonic properties than their solid counterparts. These properties make the porous gold nanoparticles very useful for lots of applications, for instance chemical sensors, cancer therapy applications. For applications, however, it is indispensable that the resonance frequency (RF) of a plasmonic structure to be tuneable. In this work we show that the RF can be set in a wide range as desired by coating the PGNs by mixed oxide layers. By changing the composition of the coating layer, that is the mixture ratio, the RF can be shifted practically continuously in a wide range determined by the refractive index of the used oxides. As a demonstration, PGNs were coated with mixed alumina-titania oxide layers (5–7 nm) using plasma-enhanced atomic layer deposition method. The oxide layer, beside as a tuning tool, also stabilises the structure of the PGNs when are exposed to elevated temperature. This is shown by the influence of the temperature (from $$350\, ^{\circ }\hbox {C}$$ 350 ∘ C up to $$900\, ^{\circ }\hbox {C}$$ 900 ∘ C ) on the morphology, and as a consequence the optical extinction spectra, of the oxide coated PGNs.

scholarly journals Sizing gold nanoparticles by optical extinction spectroscopy

2004 ◽  
Vol 16 (1) ◽  
pp. 158-163 ◽  
Author(s):  
L B Scaffardi ◽  
N Pellegri ◽  
O de Sanctis ◽  
J O Tocho
Keyword(s):  
Gold Nanoparticles ◽  
Optical Extinction ◽  
Optical Extinction Spectroscopy

scholarly journals Optical micro-spectroscopy of single metallic nanoparticles: quantitative extinction and transient resonant four-wave mixing

2015 ◽  
Vol 184 ◽  
pp. 305-320 ◽  
Author(s):  
Lukas Payne ◽  
George Zoriniants ◽  
Francesco Masia ◽  
Kenton P. Arkill ◽  
Paul Verkade ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Four Wave Mixing ◽  
Particle Analysis ◽  
Imaging Method ◽  
Wide Field ◽  
Wave Mixing ◽  
Extinction Cross Section ◽  
Optical Extinction ◽  
Aspect Ratios ◽  
Sensing Applications

We report a wide-field imaging method to rapidly and quantitatively measure the optical extinction cross-section σext (also polarisation resolved) of a large number of individual gold nanoparticles, for statistically-relevant single particle analysis. We demonstrate a sensitivity of 5 nm2 in σext, enabling detection of single 5 nm gold nanoparticles with total acquisition times in the 1 min range. Moreover, we have developed an analytical model of the polarisation resolved σext, which enabled us to extract geometrical particle aspect ratios from the measured σext. Using this method, we have characterized a large number of nominally-spherical gold nanoparticles in the 10–100 nm size range. Furthermore, the method provided measurements of in-house fabricated nanoparticle conjugates, allowing distinction of individual dimers from single particles and larger aggregates. The same particle conjugates were investigated correlatively by phase-resolved transient resonant four-wave mixing micro-spectroscopy. A direct comparison of the phase-resolved response between single gold nanoparticles and dimers highlighted the promise of the four-wave mixing technique for sensing applications with dimers as plasmon rulers.

scholarly journals Optical extinction for determining the size distribution of gold nanoparticles fabricated by ultra-short pulsed laser ablation

2008 ◽  
Vol 93 (4) ◽  
pp. 967-971 ◽  
Author(s):  
G. A. Torchia ◽  
L. B. Scaffardi ◽  
C. Méndez ◽  
P. Moreno ◽  
J. O. Tocho ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Laser Ablation ◽  
Size Distribution ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Optical Extinction

scholarly journals Technical note: optical extinction coefficient of polydisperse spherical gold nanoparticles in water

2017 ◽  
Vol 12 (4) ◽  
Author(s):  
Jia Cherng Chong ◽  
Lee Siew Ling ◽  
Noriah Bidin
Keyword(s):  
Gold Nanoparticles ◽  
Extinction Coefficient ◽  
Spectral Characteristics ◽  
Particle Diameter ◽  
Resonance Wavelength ◽  
Dipole Approximation ◽  
Technical Note ◽  
Particle Sizes ◽  
Optical Extinction ◽  
Plasmon Resonance Peak

The extinction coefficients of polydispersed gold nanoparticles up to σ = 360 nm were computed via exact solution of Mie theory. A narrow extinction peak around 520 nm occurs for mean particle sizes <d> within dipole approximation limit. Spectral characteristics for extinction coefficient computed based on increasing mean particle sizes, degree of polydispersity, composition ratio of bimodal size distributions and changes in dispersant temperature are compared. As mean particle sizes increases, the plasmon resonance peak red-shifts and broadens skewing towards infrared. Increasing polydispersity on mean particle diameter beyond dipole approximation limit decreases peak extinction coefficient values. Increasing temperature from ambient to boiling changes the peak extinction coefficient intensity value by an order of 10^-13 while resonance wavelength remains unchanged.

scholarly journals A computational analysis of nanoparticle-mediated optical breakdown

2021 ◽  
Author(s):  
Yevgeniy R. Davletsin
Keyword(s):  
Gold Nanoparticles ◽  
Optical Properties ◽  
Laser Pulse ◽  
Optical Breakdown ◽  
Wavelength Dependence ◽  
Gold Nanorod ◽  
Valuable Insight ◽  
Breakdown Threshold ◽  
Optical Extinction ◽  
Extinction Spectra

A theoretical model of the optical breakdown phenomena during picosecond and femtosecond laser pulse exposure with gold nanoparticles in water was developed. The model provides new and valuable insight into the dependence of the optical breakdown on the wavelength, morphology and environment in the vicinity of the nanoparticles. The developed model was successfully validated against experimental data, which also revealed some insights to the criterion for optical breakdown. Three studies were performed using the model. In the first study, the effects of the dielectric environment on the optical extinction spectra of individual bare and silica-coated gold nanorods were examined. The experimental extinction spectra of an individual gold nanorod was compared to a calculation from a numerical model that included environmental features present in the measurements and the morphology of the corresponding nanorod measured by transmission electron microscopy. The combination of these experimental and theoretical tools permitted a detailed interpretation of the optical properties of an individual gold nanorod. In the second study, a strongly coupled finite element model of nanoparticle-mediated optical breakdown phenomena was developed. This model was used to theoretically study a 6 ps laser pulse interaction with uncoupled and plasmon coupled gold nanoparticles. The study showed how the one-dimensional assembly of nanoparticles affects the optical breakdown threshold of its surroundings. The optical breakdown threshold had a stronger dependence on the optical near-field enhancement than on the volume of the nanostructure or its absorption cross-section. Finally, a model was developed to study the wavelength dependence of the threshold of gold nanorod-mediated optical breakdown during picosecond and femtosecond near infrared optical pulses. This study showed that the wavelength dependence in the picosecond regime is governed solely by the changes of the nanorod’s optical properties. On the other hand, the optical breakdown during femtosecond pulse exposures was found to depend on the multiphoton ionization and its wavelength dependence when, Eratio, the ratio of the maximum electric field from the outside to the inside of the nanorod was greater than 7. The developed model and conducted research deepens the understanding of the nanoparticlemediated optical breakdown in water and updates the theoretical formulation of the process with the latest findings, which leads to advancing this technology further.

Optical Extinction Spectroscopy of Oblate, Prolate and Ellipsoid Shaped Gold Nanoparticles: Experiments and Theory

Plasmonics ◽  
2006 ◽  
Vol 1 (2-4) ◽  
pp. 135-140 ◽  
Author(s):  
Johan Grand ◽  
Pierre-Michel Adam ◽  
Anne-Sophie Grimault ◽  
Alexandre Vial ◽  
Marc Lamy de la Chapelle ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Optical Extinction ◽  
Optical Extinction Spectroscopy

scholarly journals Synthesis and Bioconjugation of Gold Nanoparticles as Potential Molecular Probes for Light-Based Imaging Techniques

2007 ◽  
Vol 2007 ◽  
pp. 1-10 ◽  
Author(s):  
Raja Gopal Rayavarapu ◽  
Wilma Petersen ◽  
Constantin Ungureanu ◽  
Janine N. Post ◽  
Ton G. van Leeuwen ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Optical Imaging ◽  
Hydrophobic Interactions ◽  
Imaging Techniques ◽  
Gold Surface ◽  
Molecular Probes ◽  
Carcinoma Cells ◽  
Optical Extinction ◽  
Breast Carcinoma Cells ◽  
Electrostatic And Hydrophobic Interactions

We have synthesized and characterized gold nanoparticles (spheres and rods) with optical extinction bands within the “optical imaging window.” The intense plasmon resonant driven absorption and scattering peaks of these nanoparticles make them suitable as contrast agents for optical imaging techniques. Further, we have conjugated these gold nanoparticles to a mouse monoclonal antibody specific to HER2 overexpressing SKBR3 breast carcinoma cells. The bioconjugation protocol uses noncovalent modes of binding based on a combination of electrostatic and hydrophobic interactions of the antibody and the gold surface. We discuss various aspects of the synthesis and bioconjugation protocols and the characterization results of the functionalized nanoparticles. Some proposed applications of these potential molecular probes in the field of biomedical imaging are also discussed.

scholarly journals A computational analysis of nanoparticle-mediated optical breakdown

2021 ◽  
Author(s):  
Yevgeniy R. Davletsin
Keyword(s):  
Gold Nanoparticles ◽  
Optical Properties ◽  
Laser Pulse ◽  
Optical Breakdown ◽  
Wavelength Dependence ◽  
Gold Nanorod ◽  
Valuable Insight ◽  
Breakdown Threshold ◽  
Optical Extinction ◽  
Extinction Spectra

A theoretical model of the optical breakdown phenomena during picosecond and femtosecond laser pulse exposure with gold nanoparticles in water was developed. The model provides new and valuable insight into the dependence of the optical breakdown on the wavelength, morphology and environment in the vicinity of the nanoparticles. The developed model was successfully validated against experimental data, which also revealed some insights to the criterion for optical breakdown. Three studies were performed using the model. In the first study, the effects of the dielectric environment on the optical extinction spectra of individual bare and silica-coated gold nanorods were examined. The experimental extinction spectra of an individual gold nanorod was compared to a calculation from a numerical model that included environmental features present in the measurements and the morphology of the corresponding nanorod measured by transmission electron microscopy. The combination of these experimental and theoretical tools permitted a detailed interpretation of the optical properties of an individual gold nanorod. In the second study, a strongly coupled finite element model of nanoparticle-mediated optical breakdown phenomena was developed. This model was used to theoretically study a 6 ps laser pulse interaction with uncoupled and plasmon coupled gold nanoparticles. The study showed how the one-dimensional assembly of nanoparticles affects the optical breakdown threshold of its surroundings. The optical breakdown threshold had a stronger dependence on the optical near-field enhancement than on the volume of the nanostructure or its absorption cross-section. Finally, a model was developed to study the wavelength dependence of the threshold of gold nanorod-mediated optical breakdown during picosecond and femtosecond near infrared optical pulses. This study showed that the wavelength dependence in the picosecond regime is governed solely by the changes of the nanorod’s optical properties. On the other hand, the optical breakdown during femtosecond pulse exposures was found to depend on the multiphoton ionization and its wavelength dependence when, Eratio, the ratio of the maximum electric field from the outside to the inside of the nanorod was greater than 7. The developed model and conducted research deepens the understanding of the nanoparticlemediated optical breakdown in water and updates the theoretical formulation of the process with the latest findings, which leads to advancing this technology further.

How a sheperd guides a sheep herd?

1984 ◽  
Vol 75 ◽  
pp. 331-337
Author(s):  
Richard Greenberg
Keyword(s):  
Point Of View ◽  
Single Ring ◽  
Damping Effects ◽  
Ring Particle

ABSTRACTThe mechanism by which a shepherd satellite exerts a confining torque on a ring is considered from the point of view of a single ring particle. It is still not clear how one might most meaningfully include damping effects and other collisional processes into this type of approach to the problem.

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