Modelling the Optical Properties of Soot Particles under Various Aging Conditions

As atmospheric fresh soot particles age, they become coated with other chemical species. This transforms their physicochemical properties and affects their optical characteristics, which is of great importance to air quality, the environment and climate change. One of the predominantly occurring states of soot particles in the ambient environment is the core-shell mixing state. In this study, we used the core-shell model to calculate the optical absorption, scattering and extinction efficiency, absorption proportion and absorption exponent of coated soot particles. We then investigated the effects of different core sizes (D0), incident wavelengths (λ), coating materials and coating thicknesses on these optical characteristics. Absorption efficiency and absorption proportion of soot particles decreased as the coating became thicker, at core sizes of D0 = 20, 50 and 100 nm and λ = 405, 532 and 781 nm, regardless of the type of coating material. As the coating thickness increased, the absorption exponent (β) of inorganic-coated soot particles tended to rise and then fall, while the β value of organic-coated soot particles kept increasing. Our results advance our scientific understanding of the interaction of optical properties with chemical composition, mixing state, and aging processes of soot particles in the atmosphere.

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Light-Scattering Simulations from Spherical Bimetallic Core–Shell Nanoparticles

Micromachines ◽

10.3390/mi12040359 ◽

2021 ◽

Vol 12 (4) ◽

pp. 359

Author(s):

Francesco Ruffino

Keyword(s):

Optical Properties ◽

Light Scattering ◽

Bimetallic Nanoparticles ◽

Dominant Role ◽

Scattered Light ◽

Specific Interaction ◽

Surface Enhanced Raman Spectroscopy ◽

Localized Surface Plasmon ◽

Core Shell ◽

The Core

Bimetallic nanoparticles show novel electronic, optical, catalytic or photocatalytic properties different from those of monometallic nanoparticles and arising from the combination of the properties related to the presence of two individual metals but also from the synergy between the two metals. In this regard, bimetallic nanoparticles find applications in several technological areas ranging from energy production and storage to sensing. Often, these applications are based on optical properties of the bimetallic nanoparticles, for example, in plasmonic solar cells or in surface-enhanced Raman spectroscopy-based sensors. Hence, in these applications, the specific interaction between the bimetallic nanoparticles and the electromagnetic radiation plays the dominant role: properties as localized surface plasmon resonances and light-scattering efficiency are determined by the structure and shape of the bimetallic nanoparticles. In particular, for example, concerning core-shell bimetallic nanoparticles, the optical properties are strongly affected by the core/shell sizes ratio. On the basis of these considerations, in the present work, the Mie theory is used to analyze the light-scattering properties of bimetallic core–shell spherical nanoparticles (Au/Ag, AuPd, AuPt, CuAg, PdPt). By changing the core and shell sizes, calculations of the intensity of scattered light from these nanoparticles are reported in polar diagrams, and a comparison between the resulting scattering efficiencies is carried out so as to set a general framework useful to design light-scattering-based devices for desired applications.

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Tunable optical properties of the core-shell nanoparticles

10.1117/12.2244490 ◽

2016 ◽

Author(s):

Xin Hong ◽

Chenchen Wang

Keyword(s):

Optical Properties ◽

Core Shell ◽

Shell Nanoparticles ◽

The Core ◽

Tunable Optical Properties ◽

Core Shell Nanoparticles

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Regulating the electronic and optical properties of GaN/InN core/shell nanowires: A first-principles study

International Journal of Modern Physics B ◽

10.1142/s0217979220502148 ◽

2020 ◽

Vol 34 (25) ◽

pp. 2050214 ◽

Cited By ~ 1

Author(s):

Chang Liu ◽

Enling Li ◽

Tuo Peng ◽

Kaifei Bai ◽

Yanpeng Zheng ◽

...

Keyword(s):

Optical Properties ◽

First Principles ◽

Core Shell ◽

First Principles Calculations ◽

Electronic And Optical Properties ◽

Gan Nanowires ◽

The Core ◽

Light Region ◽

Calculation Results ◽

Shell Nanowires

In this paper, electronic and optical properties of GaN/InN core/shell nanowires (CSNWs) have been theoretically investigated through the first principles calculations. The binding energy of In and N atoms on surface of six crystal planes along the [Formula: see text]-axis of GaN nanowires are all negative, which indicate that In and N atoms can be effectively deposited on the surface of GaN nanowires and preparing GaN/InN CSNWs is feasible theoretically. Calculation results of electronic properties indicate that the core/shell ratio and diameter of GaN/InN CSNWs have significant effect on the band structure, bandgap can be effectively adjusted when keeping the number of GaN layers unchanged and changing the number of InN layers. Moreover, with the increase in the number of InN layers, the absorption spectrum of GaN/InN CSNW has significant redshift and few weak absorption peaks appear in the visible light region.

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Ag2S/ZnS nanocomposites: Synthesis, structure and optical properties

International Journal of Modern Physics B ◽

10.1142/s0217979221500338 ◽

2020 ◽

pp. 2150033

Author(s):

M. A. Ramazanov ◽

S. G. Nuriyeva ◽

H. A. Shirinova ◽

A. H. Karimova ◽

M. A. Nuriyev

Keyword(s):

Optical Properties ◽

Structural Investigation ◽

Emission Spectra ◽

Structural Features ◽

Core Shell ◽

Zns Nanoparticles ◽

Sem Images ◽

X Ray ◽

The Core ◽

Novel Method

Ag2S/ZnS nanocomposites were synthesized using a novel method, and their structural features and optical properties were also investigated. For the structural investigation of the core/shell-like nanocomposites, X-ray powder diffraction technique (XRD) and scanning electron microscopy (SEM) were used. Optical features of Ag2S/ZnS nanocomposites were studied by UV-Vis absorption and photoluminescence spectroscopy (PL). According to the SEM images, the sizes of the Ag2S, ZnS nanoparticles and Ag2S/ZnS core/shell-like nanocomposites are in the region of the 10–15; 25–50 and 15–80 nm, respectively. Furthermore, the absorption spectroscopy indicates that the bandgap of Ag2S/ZnS nanocomposites is approximately 2.4 eV. By comparison of the intensities of the emission spectra, it was clear that the intensity of Ag2S/ZnS is much lower than that of ZnS.

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Synthesis and Characterization of the Core-Shell CdTe/ZnS Quantum Dots

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.60-61.165 ◽

2009 ◽

Vol 60-61 ◽

pp. 165-169 ◽

Cited By ~ 2

Author(s):

Shi Chao Xu ◽

Cui Cui Yao ◽

Ji Mei Zhang ◽

Zhao Dai ◽

Guo Zheng ◽

...

Keyword(s):

Quantum Dots ◽

Optical Properties ◽

Colloidal Particles ◽

Resonance Energy ◽

Quantum Yields ◽

Diagnostic Process ◽

Core Shell ◽

The Core ◽

Average Size ◽

Cdte Core

Core-shell quantum dots are colloidal particles consisting of a semiconductor core and a shell material as an outer coating layer. It can be utilized to develop sensitive methods for the detection of specific biological entities, such as microbial species, their transcription products, and single genes etc. The goal of current research is to synthesize CdTe and core-shell CdTe/ZnS quantum dots (QDs) with an improved process, and to investigate their properties. Well-dispersed CdTe core was prepared in aqueous phase with using 3-mercaptopropionic acid (MPA) as stabilizer under conditions of pH 9.1, temperature of 100 °C, refluxing for 6h, and mol ratio of Cd2+/Te2-/MPA is 1:0.5:2.4. Average size of 8 nm CdTe core was conformed via transmission electron microscopy (TEM). Core-shell CdTe/ZnS QDs were then synthesized to improve the optical properties and biocompatibility of CdTe core. Various conditions were researched to obtain the core-shell QDs with the best optical properties, such as quantum yields, fluorescence intensity etc. The results indicated that the core-shell qualified CdTe/ZnS was prepared under conditions of pH 9.0, temperature of 45 °C, refluxing for 1h, and mol ratio of CdTe/S2-/Zn2+ is 4/1/1. CdTe/ZnS with average size of 10 nm were achieved and conformed via TEM. Moreover, red shift of a maximum emission wavelength from 547 nm of CdTe to 587 of CdTe/ZnS was observed via fluorescence spectrum (FS), which inferred the growth of QDs and formation of ZnS shells. The achieved ZnS shell make CdTe core less toxic and more biocompatible, it will be useful in biological labeling, diagnostic process and biosensing system based on fluorescence resonance energy transition (FRET).

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Exploring the benefits of electron tomography to characterize the precise morphology of core–shell Au@Ag nanoparticles and its implications on their plasmonic properties

Nanoscale ◽

10.1039/c4nr03017f ◽

2014 ◽

Vol 6 (21) ◽

pp. 12696-12702 ◽

Cited By ~ 10

Author(s):

J. C. Hernández-Garrido ◽

M. S. Moreno ◽

C. Ducati ◽

L. A. Pérez ◽

P. A. Midgley ◽

...

Keyword(s):

Optical Properties ◽

3D Reconstruction ◽

Ag Nanoparticles ◽

Electron Tomography ◽

Core Shell ◽

The Core

Here we demonstrate the importance of having a precise morphological 3D reconstruction of the core in comparison with an ideal nanoparticle for a better understanding of their optical properties.

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Au Nanobipyramids with Pt decoration enveloped in TiO2 nanoboxes for photocatalytic reaction

Nanoscale Advances ◽

10.1039/d1na00092f ◽

2021 ◽

Author(s):

Weijian Gao ◽

Caixia Kan ◽

Shanlin Ke ◽

Qinru Yun ◽

Xingzhong Zhu ◽

...

Keyword(s):

Optical Properties ◽

Surface Plasmon Resonance ◽

Noble Metal ◽

Surface Plasmon ◽

Plasmon Resonance ◽

Core Shell ◽

Photocatalytic Reaction ◽

Metal Nanocrystals ◽

The Core

Noble metal nanocrystals and the core-shell nanocomposites have attracted particular interest due to their unique optical properties originated from the surface plasmon resonance (SPR) and wide applications related to the...

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Elastic forces drive nonequilibrium pattern formation in a model of nanocrystal ion exchange

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2114551118 ◽

2021 ◽

Vol 118 (52) ◽

pp. e2114551118

Author(s):

Layne B. Frechette ◽

Christoph Dellago ◽

Phillip L. Geissler

Keyword(s):

Ion Exchange ◽

Rational Design ◽

Chemical Potential ◽

Chemical Species ◽

Core Shell ◽

Chemical Transformations ◽

Elastic Deformations ◽

The Core ◽

Elastic Forces ◽

Far From Equilibrium

Chemical transformations, such as ion exchange, are commonly employed to modify nanocrystal compositions. Yet the mechanisms of these transformations, which often operate far from equilibrium and entail mixing diverse chemical species, remain poorly understood. Here we explore an idealized model for ion exchange in which a chemical potential drives compositional defects to accumulate at a crystal’s surface. These impurities subsequently diffuse inward. We find that the nature of interactions between sites in a compositionally impure crystal strongly impacts exchange trajectories. In particular, elastic deformations which accompany lattice-mismatched species promote spatially modulated patterns in the composition. These same patterns can be produced at equilibrium in core/shell nanocrystals, whose structure mimics transient motifs observed in nonequilibrium trajectories. Moreover, the core of such nanocrystals undergoes a phase transition—from modulated to unstructured—as the thickness or stiffness of the shell is decreased. Our results help explain the varied patterns observed in heterostructured nanocrystals produced by ion exchange and suggest principles for the rational design of compositionally patterned nanomaterials.

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The Performance of Active Coated Nanoparticles Based on Quantum-Dot Gain Media

Advances in OptoElectronics ◽

10.1155/2012/368786 ◽

2012 ◽

Vol 2012 ◽

pp. 1-6 ◽

Cited By ~ 10

Author(s):

Sawyer D. Campbell ◽

Richard W. Ziolkowski

Keyword(s):

Quantum Dots ◽

Optical Properties ◽

Quantum Dot ◽

Relative Size ◽

Core Shell ◽

The Core ◽

Coated Nanoparticles ◽

Dot Gain ◽

Band Gap Structure ◽

Gain Media

Quantum-dots (QDs) provide an exciting option for the gain media incorporated in active coated nanoparticles (CNPs) because they possess large gain coefficients resulting from their extreme confinement effects. The optical properties of core/shell QDs can be tuned by changing the relative size of the core/shell, that is, by effectively changing its band gap structure. Similarly, the resonance of a CNP can be adjusted by changing the relative sizes of its layers. It is demonstrated here that by optimally locating the QDs inside a resonant CNP structure it is possible to greatly enhance the intrinsic amplifying behavior of the combined QD-CNP system.

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