scholarly journals An analytical approximation to measure the extinction cross-section using: Localized Waves

2022 ◽  
Vol 6 (1) ◽  
pp. 015003
Author(s):  
Irving Rondón
Keyword(s):  
Cross Section ◽  
General Expression ◽  
Analytical Approximation ◽  
Optical Theorem ◽  
Input Beam ◽  
Extinction Cross Section ◽  
Localized Waves

Abstract We present a general expression for the optical theorem in terms of Localized Waves. This representation is well-known and commonly used to generate Frozen waves, Xwaves, and other propagation invariant beams. We analyze several examples using different input beam sources on a circular detector to measure the extinction cross-section.

scholarly journals Generalization of the Optical Theorem to an Arbitrary Multipole Excitation of a Particle near a Transparent Substrate

Mathematics ◽  
2021 ◽  
Vol 9 (24) ◽  
pp. 3244
Author(s):  
Yuri A. Eremin ◽  
Thomas Wriedt
Keyword(s):  
Cross Section ◽  
Scattered Field ◽  
Arbitrary Order ◽  
Electric Quadrupole ◽  
Optical Theorem ◽  
Extinction Cross Section ◽  
Special Representation ◽  
Transparent Substrate ◽  
Finite Integrals

In the present paper, the generalization of the optical theorem to the case of a penetrable particle deposited near a transparent substrate that is excited by a multipole of an arbitrary order and polarization has been derived. In the derivation we employ classic Maxwell’s theory, Gauss’s theorem, and use a special representation for the multipole excitation. It has been shown that the extinction cross-section can be evaluated by the calculation of some specific derivatives from the scattered field at the position of the multipole location, in addition to some finite integrals which account for the multipole polarization and the presence of the substrate. Finally, the present paper considers some specific examples for the excitation of a particle by an electric quadrupole.

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.

Extinction cross section of a dielectric strip

1988 ◽  
Vol 36 (5) ◽  
pp. 696-706 ◽  
Author(s):  
S. Dowerah ◽  
A. Chakrabarti
Keyword(s):  
Cross Section ◽  
Extinction Cross Section

Analytical approximation of cross-section effects on charge exchange spectra observed in hot fusion plasmas

1995 ◽  
Vol 37 (2) ◽  
pp. 71-94 ◽  
Author(s):  
M von Hellermann ◽  
P Breger ◽  
J Frieling ◽  
R Konig ◽  
W Mandl ◽  
...  
Keyword(s):  
Cross Section ◽  
Charge Exchange ◽  
Analytical Approximation ◽  
Fusion Plasmas

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.

A discussion on infared astronomy - On the chemistry of Jupiter's upper atmosphere

1969 ◽  
Vol 264 (1150) ◽  
pp. 151-151
Keyword(s):  
Ultraviolet Radiation ◽  
Cross Section ◽  
Infrared Radiation ◽  
Organic Molecules ◽  
General Procedure ◽  
Analytical Approximation ◽  
Upper Atmosphere ◽  
Rapid Rise ◽  
Absorption Bands ◽  
Jovian Atmosphere

The infrared opacity of Jupiter’s upper atmosphere will be influenced by line blanketing resulting from strong absorption bands of ammonia and organic molecules. In order to calculate these effects eventually, we conduct a first investigation into the ion-molecule chemistry of the upper Jovian atmosphere. Experimental results show that intense ultraviolet radiation reacts with the constituents of the Jovian atmosphere to produce C2H4> ^2^65 a, and higher polymers. The general procedure for calculating both equilibrium and non-equilibrium abundances of these products is formulated and applied to the case of the surface passage of a satellite shadow. A specific example is made of ethylene, for which an analytical approximation gives 10 (to power of 10) molecules in an atmospheric column of 1 cm2 cross-section after a very rapid rise to equilibrium. Such a concentration of ethylene does not substantially affect the infrared radiation in the shadow.

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