dorsal/arxiv
View SchemaLocal anisotropy and giant enhancement of local electromagnetic fields in fractal aggregates of metal nanoparticles
| Authors | Sergei V. Karpov, Valeriy S. Gerasimov, Ivan L. Isaev, Vadim A. Markel |
|---|---|
| Categories | |
| ArXiv ID | physics/0507202 |
| URL | https://arxiv.org/abs/physics/0507202 |
| DOI | 10.1103/PhysRevB.72.205425 |
| Journal | Phys. Rev. B 72, 205425 (2005) |
Abstract
We have shown within the quasistatic approximation that the giant fluctuations of local electromagnetic field in random fractal aggregates of silver nanospheres are strongly correlated with a local anisotropy factor S which is defined in this paper. The latter is a purely geometrical parameter which characterizes the deviation of local environment of a given nanosphere in an aggregate from spherical symmetry. Therefore, it is possible to predict the sites with anomalously large local fields in an aggregate without explicitly solving the electromagnetic problem. We have also demonstrated that the average (over nanospheres) value of S does not depend noticeably on the fractal dimension D, except when D approaches the trivial limit D=3. In this case, as one can expect, the average local environment becomes spherically symmetrical and S approaches zero. This corresponds to the well-known fact that in trivial aggregates fluctuations of local electromagnetic fields are much weaker than in fractal aggregates. Thus, we find that, within the quasistatics, the large-scale geometry does not have a significant impact on local electromagnetic responses in nanoaggregates in a wide range of fractal dimensions. However, this prediction is expected to be not correct in aggregates which are sufficiently large for the intermediate- and radiation-zone interaction of individual nanospheres to become important.
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"abstract": "We have shown within the quasistatic approximation that the giant\nfluctuations of local electromagnetic field in random fractal aggregates of\nsilver nanospheres are strongly correlated with a local anisotropy factor S\nwhich is defined in this paper. The latter is a purely geometrical parameter\nwhich characterizes the deviation of local environment of a given nanosphere in\nan aggregate from spherical symmetry. Therefore, it is possible to predict the\nsites with anomalously large local fields in an aggregate without explicitly\nsolving the electromagnetic problem. We have also demonstrated that the average\n(over nanospheres) value of S does not depend noticeably on the fractal\ndimension D, except when D approaches the trivial limit D=3. In this case, as\none can expect, the average local environment becomes spherically symmetrical\nand S approaches zero. This corresponds to the well-known fact that in trivial\naggregates fluctuations of local electromagnetic fields are much weaker than in\nfractal aggregates. Thus, we find that, within the quasistatics, the\nlarge-scale geometry does not have a significant impact on local\nelectromagnetic responses in nanoaggregates in a wide range of fractal\ndimensions. However, this prediction is expected to be not correct in\naggregates which are sufficiently large for the intermediate- and\nradiation-zone interaction of individual nanospheres to become important.",
"arxiv_id": "physics/0507202",
"authors": [
"Sergei V. Karpov",
"Valeriy S. Gerasimov",
"Ivan L. Isaev",
"Vadim A. Markel"
],
"categories": [
"physics.optics"
],
"doi": "10.1103/PhysRevB.72.205425",
"journal_ref": "Phys. Rev. B 72, 205425 (2005)",
"title": "Local anisotropy and giant enhancement of local electromagnetic fields in fractal aggregates of metal nanoparticles",
"url": "https://arxiv.org/abs/physics/0507202"
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