Advanced

On the physical limitations for radio frequency absorption in gold nanoparticle suspensions

Nordebo, Sven LU ; Dalarsson, Mariana; Ivanenko, Yevhen LU ; Sjöberg, Daniel LU and Bayford, Richard (2017) In Journal of Physics D: Applied Physics 50(15).
Abstract

This paper presents a study of the physical limitations for radio frequency absorption in gold nanoparticle (GNP) suspensions. A spherical geometry is considered consisting of a spherical suspension of colloidal GNPs characterized as an arbitrary passive dielectric material which is immersed in an arbitrary lossy medium. A relative heating coefficient and a corresponding optimal near field excitation are defined, taking the skin effect of the surrounding medium into account. The classical Mie theory for lossy media is also revisited, and it is shown that the optimal permittivity function yielding a maximal absorption inside the spherical suspension is a conjugate match with respect to the surrounding lossy material. A convex... (More)

This paper presents a study of the physical limitations for radio frequency absorption in gold nanoparticle (GNP) suspensions. A spherical geometry is considered consisting of a spherical suspension of colloidal GNPs characterized as an arbitrary passive dielectric material which is immersed in an arbitrary lossy medium. A relative heating coefficient and a corresponding optimal near field excitation are defined, taking the skin effect of the surrounding medium into account. The classical Mie theory for lossy media is also revisited, and it is shown that the optimal permittivity function yielding a maximal absorption inside the spherical suspension is a conjugate match with respect to the surrounding lossy material. A convex optimization approach is used to investigate the broadband realizability of an arbitrary passive material to approximate the desired conjugate match over a finite bandwidth, similar to the approximation of a metamaterial. A narrowband realizability study shows that for a surrounding medium consisting of a weak electrolyte solution, the electromagnetic heating, due to the electrophoretic (plasmonic) resonance phenomena inside the spherical GNP suspension, can be significant in the microwave regime, provided that the related Drude parameters can be tuned into (or near to) resonance. As a demonstration, some realistic Drude parameters are investigated concerning the volume fraction, mass, and friction constant of the GNPs. The amount of charge that can be accommodated by the GNPs is identified as one of the most important design parameters. However, the problem of reliably modelling, measuring and controlling the charge number of coated GNPs is not yet fully understood, and is still an open research issue in this field. The presented theory and related physical limitations provide a useful framework for further research in this direction. Future research is also aimed at an expansion towards arbitrary suspension geometries and the inclusion of thermodynamical analysis.

(Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
gold nanoparticles, Mie theory, optimal absorption
in
Journal of Physics D: Applied Physics
volume
50
issue
15
publisher
IOP Publishing
external identifiers
  • scopus:85016154351
  • wos:000397500500001
ISSN
0022-3727
DOI
10.1088/1361-6463/aa5a89
language
English
LU publication?
yes
id
e418149a-2609-4b03-a198-9a455972d5e0
date added to LUP
2017-04-05 14:30:28
date last changed
2018-05-29 11:19:42
@article{e418149a-2609-4b03-a198-9a455972d5e0,
  abstract     = {<p>This paper presents a study of the physical limitations for radio frequency absorption in gold nanoparticle (GNP) suspensions. A spherical geometry is considered consisting of a spherical suspension of colloidal GNPs characterized as an arbitrary passive dielectric material which is immersed in an arbitrary lossy medium. A relative heating coefficient and a corresponding optimal near field excitation are defined, taking the skin effect of the surrounding medium into account. The classical Mie theory for lossy media is also revisited, and it is shown that the optimal permittivity function yielding a maximal absorption inside the spherical suspension is a conjugate match with respect to the surrounding lossy material. A convex optimization approach is used to investigate the broadband realizability of an arbitrary passive material to approximate the desired conjugate match over a finite bandwidth, similar to the approximation of a metamaterial. A narrowband realizability study shows that for a surrounding medium consisting of a weak electrolyte solution, the electromagnetic heating, due to the electrophoretic (plasmonic) resonance phenomena inside the spherical GNP suspension, can be significant in the microwave regime, provided that the related Drude parameters can be tuned into (or near to) resonance. As a demonstration, some realistic Drude parameters are investigated concerning the volume fraction, mass, and friction constant of the GNPs. The amount of charge that can be accommodated by the GNPs is identified as one of the most important design parameters. However, the problem of reliably modelling, measuring and controlling the charge number of coated GNPs is not yet fully understood, and is still an open research issue in this field. The presented theory and related physical limitations provide a useful framework for further research in this direction. Future research is also aimed at an expansion towards arbitrary suspension geometries and the inclusion of thermodynamical analysis.</p>},
  articleno    = {155401},
  author       = {Nordebo, Sven and Dalarsson, Mariana and Ivanenko, Yevhen and Sjöberg, Daniel and Bayford, Richard},
  issn         = {0022-3727},
  keyword      = {gold nanoparticles,Mie theory,optimal absorption},
  language     = {eng},
  month        = {03},
  number       = {15},
  publisher    = {IOP Publishing},
  series       = {Journal of Physics D: Applied Physics},
  title        = {On the physical limitations for radio frequency absorption in gold nanoparticle suspensions},
  url          = {http://dx.doi.org/10.1088/1361-6463/aa5a89},
  volume       = {50},
  year         = {2017},
}