scholarly journals Using the DDA (Discrete Dipole Approximation) Method in Determining the Extinction Cross Section of Black Carbon

2015 ◽  
Vol 22 (1) ◽  
pp. 153-164 ◽  
Author(s):  
Krzysztof Skorupski
Keyword(s):  
Refractive Index ◽  
Black Carbon ◽  
Cross Section ◽  
Main Parameter ◽  
Complex Refractive Index ◽  
Dipole Approximation ◽  
Discrete Dipole Approximation ◽  
Extinction Cross Section ◽  
Quality Of Results

AbstractBC (Black Carbon), which can be found in the atmosphere, is characterized by a large value of the imaginary part of the complex refractive index and, therefore, might have an impact on the global warming effect. To study the interaction of BC with light often computer simulations are used. One of the methods, which are capable of performing light scattering simulations by any shape, is DDA (Discrete Dipole Approximation). In this work its accuracy was estimated in respect to BC structures using the latest stable version of the ADDA (vr. 1.2) algorithm. As the reference algorithm the GMM (Generalized Multiparticle Mie-Solution) code was used. The study shows that the number of volume elements (dipoles) is the main parameter that defines the quality of results. However, they can be improved by a proper polarizability expression. The most accurate, and least time consuming, simulations were observed for IGT_SO. When an aggregate consists of particles composed of ca. 750 volume elements (dipoles), the averaged relative extinction error should not exceed ca. 4.5%.

scholarly journals Simulated Optical Properties of Gold Nanocubes and Nanobars by Discrete Dipole Approximation

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Mohammed Alsawafta ◽  
Mamoun Wahbeh ◽  
Vo-Van Truong
Keyword(s):  
Absorption Spectrum ◽  
Cross Section ◽  
Longitudinal Mode ◽  
Transverse Mode ◽  
Dipole Approximation ◽  
Discrete Dipole Approximation ◽  
Absorption Cross ◽  
Extinction Cross Section ◽  
Band Position ◽  
Mode Tm

The absorption spectra for a gold nanocube and for a gold nanobar are calculated by using the Discrete Dipole Approximation (DDA). The results show the excitation of a single albeit broad surface plasmon (SP) band of the gold nanocube. The extinction cross section of the gold nanocube is dominated by the absorption cross section that gains importance as the width increases. Further increasing the nanocube size beyond 80 nm will result in an optical response mainly characterized by scattering properties. The absorption spectrum of the nanobar shows the excitation of both the longitudinal mode (LM) and the transverse mode (TM). The nanobar is also compared to a cylinder, a spherically capped cylinder, and a spheroid of the same aspect ratio. The band position of the TM of the nanobar is red-shifted as compared to the ones calculated for other morphologies, while the LM is either blue-shifted or red-shifted depending on the morphologies considered.

scholarly journals Aggregation affects optical properties and photothermal heating of gold nanospheres

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yiru Wang ◽  
Zhe Gao ◽  
Zonghu Han ◽  
Yilin Liu ◽  
Huan Yang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Cross Section ◽  
Laser Heating ◽  
Dipole Approximation ◽  
Gold Nanospheres ◽  
Extinction Cross Section ◽  
Heating Efficiency ◽  
Photothermal Heating ◽  
New Framework ◽  
Laser Calorimetry

AbstractLaser heating of gold nanospheres (GNS) is increasingly prevalent in biomedical applications due to tunable optical properties that determine heating efficiency. Although many geometric parameters (i.e. size, morphology) can affect optical properties of individual GNS and their heating, no specific studies of how GNS aggregation affects heating have been carried out. We posit here that aggregation, which can occur within some biological systems, will significantly impact the optical and therefore heating properties of GNS. To address this, we employed discrete dipole approximation (DDA) simulations, Ultraviolet–Visible spectroscopy (UV–Vis) and laser calorimetry on GNS primary particles with diameters (5, 16, 30 nm) and their aggregates that contain 2 to 30 GNS particles. DDA shows that aggregation can reduce the extinction cross-section on a per particle basis by 17–28%. Experimental measurement by UV–Vis and laser calorimetry on aggregates also show up to a 25% reduction in extinction coefficient and significantly lower heating (~ 10%) compared to dispersed GNS. In addition, comparison of select aggregates shows even larger extinction cross section drops in sparse vs. dense aggregates. This work shows that GNS aggregation can change optical properties and reduce heating and provides a new framework for exploring this effect during laser heating of nanomaterial solutions.

The scattering of light. I. The optical response of a finite molecular fluid

1984 ◽  
Vol 312 (1521) ◽  
pp. 251-293 ◽  
Keyword(s):  
Refractive Index ◽  
Cross Section ◽  
Complex Refractive Index ◽  
Scattered Light ◽  
Optical Response ◽  
Scattering Cross Section ◽  
Material System ◽  
Optical Extinction ◽  
Many Body Theory ◽  
Scattering Cross

We present a classical many-body theory of the optical response of a molecular fluid. The unified treatment provides mutually consistent expressions for the dielectric constant, the refractive index, the optical extinction coefficient, and the optical scattering cross section. The theory treats a finite material system and handles all surface effects associated with transmitted and scattered light. The complex refractive index and the scattering cross section will be analysed in two future papers.

scholarly journals Verification tests of frictional heat modelling results

Mechanika ◽  
2020 ◽  
Vol 26 (3) ◽  
pp. 260-264
Author(s):  
Andrzej BORAWSKI ◽  
Dariusz SZPICA ◽  
Grzegorz MIECZKOWSKI
Keyword(s):  
Friction Surface ◽  
Main Parameter ◽  
Real Life ◽  
Computer Models ◽  
Frictional Heat ◽  
Quality Of Results ◽  
Pin On Disc ◽  
Life Phenomena

Simulation tests have currently become very popular. It gives access to values and parameters which are difficult or impossible to obtain in real conditions. However, in many cases the accuracy of the results may raise concerns, as not every researcher conducts verification tests. This article looks into the quality of results obtained in virtual tests. The tests were conducted using a pin-on-disc station. The main parameter of the verification study was the temperature of the pin measured along its axis at 1mm from the friction surface. This shows that computer models produce results which accurately reflect real-life phenomena.

Complex Refractive Index Dispersion of Strong Absorbing Material Determined Using Internal Reflectance Spectra Measurement

2018 ◽  
Vol 72 (9) ◽  
pp. 1349-1353 ◽  
Author(s):  
Zhichao Deng ◽  
Jin Wang ◽  
Zhixiong Hu ◽  
Jianchun Mei ◽  
Shike Liu ◽  
...  
Keyword(s):  
Refractive Index ◽  
Complex Refractive Index ◽  
Great Difficulty ◽  
Reflectance Spectra ◽  
Optical Parameters ◽  
Refractive Index Dispersion ◽  
Absorbing Material ◽  
Measuring Tool ◽  
Internal Reflectance

Complex refractive index dispersion (CRID) of offset inks is an important spectral property that affects the quality of printing. Due to the strong absorption of offset inks, great difficulty exists when measuring their CRID. In this study, a recently proposed apparatus that can detect the internal reflectance spectra was used to measure the CRID of three strong absorbing offset inks (magenta, yellow, and cyan). Both anomalous dispersion curve and extinction coefficient curve were well determined over the spectral range of 400–750 nm. This study experimentally proves that the apparatus and related method are feasible for the CRID measurement of strong absorbing materials and could serve as a powerful measuring tool for optical parameters.

Sign in / Sign up

Export Citation Format

Share Document