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Quantifying the Plasmonic Character of Optical Excitations in a Molecular J-Aggregate

[Image: see text] The definition of plasmon at the microscopic scale is far from being understood. Yet, it is very important to recognize plasmonic features in optical excitations, as they can inspire new applications and trigger new discoveries by analogy with the rich phenomenology of metal nanopa...

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Autores principales: Guerrini, Michele, Calzolari, Arrigo, Varsano, Daniele, Corni, Stefano
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2019
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6524342/
https://www.ncbi.nlm.nih.gov/pubmed/30986064
http://dx.doi.org/10.1021/acs.jctc.9b00220
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author Guerrini, Michele
Calzolari, Arrigo
Varsano, Daniele
Corni, Stefano
author_facet Guerrini, Michele
Calzolari, Arrigo
Varsano, Daniele
Corni, Stefano
author_sort Guerrini, Michele
collection PubMed
description [Image: see text] The definition of plasmon at the microscopic scale is far from being understood. Yet, it is very important to recognize plasmonic features in optical excitations, as they can inspire new applications and trigger new discoveries by analogy with the rich phenomenology of metal nanoparticle plasmons. Recently, the concepts of plasmonicity index and the generalized plasmonicity index (GPI) have been devised as computational tools to quantify the plasmonic nature of optical excitations. The question may arise whether any strong absorption band, possibly with some sort of collective character in its microscopic origin, shares the status of plasmon. Here we demonstrate that this is not always the case, by considering a well-known class of systems represented by J-aggregates molecular crystals, characterized by the intense J band of absorption. By means of first-principles simulations, based on a many-body perturbation theory formalism, we investigate the optical properties of a J-aggregate made of push–pull organic dyes. We show that the effect of aggregation is to lower the GPI associated with the J-band with respect to the isolated dye one, which corresponds to a nonplasmonic character of the electronic excitations. In order to rationalize our finding, we then propose a simplified one-dimensional theoretical model of the J-aggregate. A useful microscopic picture of what discriminates a collective molecular crystal excitation from a plasmon is eventually obtained.
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spelling pubmed-65243422019-05-20 Quantifying the Plasmonic Character of Optical Excitations in a Molecular J-Aggregate Guerrini, Michele Calzolari, Arrigo Varsano, Daniele Corni, Stefano J Chem Theory Comput [Image: see text] The definition of plasmon at the microscopic scale is far from being understood. Yet, it is very important to recognize plasmonic features in optical excitations, as they can inspire new applications and trigger new discoveries by analogy with the rich phenomenology of metal nanoparticle plasmons. Recently, the concepts of plasmonicity index and the generalized plasmonicity index (GPI) have been devised as computational tools to quantify the plasmonic nature of optical excitations. The question may arise whether any strong absorption band, possibly with some sort of collective character in its microscopic origin, shares the status of plasmon. Here we demonstrate that this is not always the case, by considering a well-known class of systems represented by J-aggregates molecular crystals, characterized by the intense J band of absorption. By means of first-principles simulations, based on a many-body perturbation theory formalism, we investigate the optical properties of a J-aggregate made of push–pull organic dyes. We show that the effect of aggregation is to lower the GPI associated with the J-band with respect to the isolated dye one, which corresponds to a nonplasmonic character of the electronic excitations. In order to rationalize our finding, we then propose a simplified one-dimensional theoretical model of the J-aggregate. A useful microscopic picture of what discriminates a collective molecular crystal excitation from a plasmon is eventually obtained. American Chemical Society 2019-04-15 2019-05-14 /pmc/articles/PMC6524342/ /pubmed/30986064 http://dx.doi.org/10.1021/acs.jctc.9b00220 Text en Copyright © 2019 American Chemical Society This is an open access article published under an ACS AuthorChoice License (http://pubs.acs.org/page/policy/authorchoice_termsofuse.html) , which permits copying and redistribution of the article or any adaptations for non-commercial purposes.
spellingShingle Guerrini, Michele
Calzolari, Arrigo
Varsano, Daniele
Corni, Stefano
Quantifying the Plasmonic Character of Optical Excitations in a Molecular J-Aggregate
title Quantifying the Plasmonic Character of Optical Excitations in a Molecular J-Aggregate
title_full Quantifying the Plasmonic Character of Optical Excitations in a Molecular J-Aggregate
title_fullStr Quantifying the Plasmonic Character of Optical Excitations in a Molecular J-Aggregate
title_full_unstemmed Quantifying the Plasmonic Character of Optical Excitations in a Molecular J-Aggregate
title_short Quantifying the Plasmonic Character of Optical Excitations in a Molecular J-Aggregate
title_sort quantifying the plasmonic character of optical excitations in a molecular j-aggregate
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6524342/
https://www.ncbi.nlm.nih.gov/pubmed/30986064
http://dx.doi.org/10.1021/acs.jctc.9b00220
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