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Absorption and optimal plasmonic resonances for small ellipsoidal particles in lossy media

Dalarsson, Mariana; Nordebo, Sven LU ; Sjöberg, Daniel LU and Bayford, Richard (2017) In Journal of Physics D: Applied Physics 50(34).
Abstract

A new simplifed formula is derived for the absorption cross section of small dielectric ellipsoidal particles embedded in lossy media. The new expression leads directly to a closed form solution for the optimal conjugate match with respect to the surrounding medium, i.e. the optimal permittivity of the ellipsoidal particle that maximizes the absorption at any given frequency. This defnes the optimal plasmonic resonance for the ellipsoid. The optimal conjugate match represents a metamaterial in the sense that the corresponding optimal permittivity function may have negative real part (inductive properties), and can not in general be implemented as a passive material over a given bandwidth. A necessary and suffcient condition is derived... (More)

A new simplifed formula is derived for the absorption cross section of small dielectric ellipsoidal particles embedded in lossy media. The new expression leads directly to a closed form solution for the optimal conjugate match with respect to the surrounding medium, i.e. the optimal permittivity of the ellipsoidal particle that maximizes the absorption at any given frequency. This defnes the optimal plasmonic resonance for the ellipsoid. The optimal conjugate match represents a metamaterial in the sense that the corresponding optimal permittivity function may have negative real part (inductive properties), and can not in general be implemented as a passive material over a given bandwidth. A necessary and suffcient condition is derived for the feasibility of tuning the Drude model to the optimal conjugate match at a single frequency, and it is found that all the prolate spheroids and some of the (not too flat) oblate spheroids can be tuned into optimal plasmonic resonance at any desired center frequency. Numerical examples are given to illustrate the analysis. Except for the general understanding of plasmonic resonances in lossy media, it is also anticipated that the new results can be useful for feasibility studies with e.g. the radiotherapeutic hyperthermia based methods to treat cancer based on electrophoretic heating in gold nanoparticle suspensions using microwave radiation.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
absorption cross section, Particle absorption, plasmonic resonances
in
Journal of Physics D: Applied Physics
volume
50
issue
34
publisher
IOP Publishing
external identifiers
  • scopus:85027258563
  • wos:000406527200001
ISSN
0022-3727
DOI
10.1088/1361-6463/aa7c8a
language
English
LU publication?
yes
id
9cc9b688-48cb-4841-9c99-b4da63921aae
date added to LUP
2017-08-31 11:22:12
date last changed
2017-09-18 11:43:38
@article{9cc9b688-48cb-4841-9c99-b4da63921aae,
  abstract     = {<p>A new simplifed formula is derived for the absorption cross section of small dielectric ellipsoidal particles embedded in lossy media. The new expression leads directly to a closed form solution for the optimal conjugate match with respect to the surrounding medium, i.e. the optimal permittivity of the ellipsoidal particle that maximizes the absorption at any given frequency. This defnes the optimal plasmonic resonance for the ellipsoid. The optimal conjugate match represents a metamaterial in the sense that the corresponding optimal permittivity function may have negative real part (inductive properties), and can not in general be implemented as a passive material over a given bandwidth. A necessary and suffcient condition is derived for the feasibility of tuning the Drude model to the optimal conjugate match at a single frequency, and it is found that all the prolate spheroids and some of the (not too flat) oblate spheroids can be tuned into optimal plasmonic resonance at any desired center frequency. Numerical examples are given to illustrate the analysis. Except for the general understanding of plasmonic resonances in lossy media, it is also anticipated that the new results can be useful for feasibility studies with e.g. the radiotherapeutic hyperthermia based methods to treat cancer based on electrophoretic heating in gold nanoparticle suspensions using microwave radiation.</p>},
  articleno    = {345401},
  author       = {Dalarsson, Mariana and Nordebo, Sven and Sjöberg, Daniel and Bayford, Richard},
  issn         = {0022-3727},
  keyword      = {absorption cross section,Particle absorption,plasmonic resonances},
  language     = {eng},
  month        = {07},
  number       = {34},
  publisher    = {IOP Publishing},
  series       = {Journal of Physics D: Applied Physics},
  title        = {Absorption and optimal plasmonic resonances for small ellipsoidal particles in lossy media},
  url          = {http://dx.doi.org/10.1088/1361-6463/aa7c8a},
  volume       = {50},
  year         = {2017},
}