Approaching the quantum limit for nanoplasmonics

Townsend, Emily; Debrecht, Alex; Bryant, Garnett W.

doi:10.1557/jmr.2015.232

Cited by 11 publications

(23 citation statements)

References 55 publications

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“…Bryant and co-workers compared TDDFT results with exact calculations for small model linear systems. 41 , 42 More recently, Fitzgerald et al . explored single and coupled sodium atomic chains as ultrasmall molecular plasmonic nanoantennas.…”

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confidence: 99%

How To Identify Plasmons from the Optical Response of Nanostructures

Zhang¹,

et al. 2017

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A promising trend in plasmonics involves shrinking the size of plasmon-supporting structures down to a few nanometers, thus enabling control over light–matter interaction at extreme-subwavelength scales. In this limit, quantum mechanical effects, such as nonlocal screening and size quantization, strongly affect the plasmonic response, rendering it substantially different from classical predictions. For very small clusters and molecules, collective plasmonic modes are hard to distinguish from other excitations such as single-electron transitions. Using rigorous quantum mechanical computational techniques for a wide variety of physical systems, we describe how an optical resonance of a nanostructure can be classified as either plasmonic or nonplasmonic. More precisely, we define a universal metric for such classification, the generalized plasmonicity index (GPI), which can be straightforwardly implemented in any computational electronic-structure method or classical electromagnetic approach to discriminate plasmons from single-particle excitations and photonic modes. Using the GPI, we investigate the plasmonicity of optical resonances in a wide range of systems including: the emergence of plasmonic behavior in small jellium spheres as the size and the number of electrons increase; atomic-scale metallic clusters as a function of the number of atoms; and nanostructured graphene as a function of size and doping down to the molecular plasmons in polycyclic aromatic hydrocarbons. Our study provides a rigorous foundation for the further development of ultrasmall nanostructures based on molecular plasmonics.

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confidence: 99%

How To Identify Plasmons from the Optical Response of Nanostructures

Zhang¹,

et al. 2017

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“…However, at the nanoscale, single-particle and plasmonic excitations are intrinsically mixed [18], and how to recognize a plasmonic excitation is still an unsolved problem.A few approaches have been recently proposed attempting to classify the plasmonic character of the excitations of nanosystems. [11,[19][20][21][22][23][24] In particular, Bernadotte et al [11] formulated, in the framework of time-dependent density-functional theory (TDDFT), a scaling approach based on the different dependence of the energies of the excitations of nanosystems on the Coulomb kernel. Along this line, Krauter et al[23] demonstrated that the electronic wave function of plasmons, at the time-dependent Hartree-Fock level, is described by the superposition of several electron configurations, i.e.…”

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confidence: 99%

Quantifying the Plasmonic Character of Optical Excitations in Nanostructures

et al. 2016

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The identification of plasmons in systems below ∼10 nm in size is a tremendous challenge. Any sharp distinction of the excitation character (non-plasmonic vs plasmonic) becomes blurred in this range of sizes, where quantum effects become important. Here we define a plasmonicicty index that quantifies the plasmonic character of selected optical excitations in small nanostructures, starting from first principles calculations, based on (TD)DFT. This novel approach allows us to overcome the aforementioned problems, providing a direct and quantitative classification of the plasmonic character of the excitations. We show its usefulness for model metallic nanoparticles, a prototypical C-based molecule and a paradigmatic hybrid system. Our results indicate that the plasmonicity index can be exploited to solve previously unsolvable problems about the plasmonic character of complex systems, not predictable a priori.Localized surface plasmon resonances in nanostrucures interact strongly with light allowing the confinement of electromagnetic energy down to deep subwavelength regions [1,2]. This, together with their easy tunability [3], robustness [4] and field enhancement properties [5], provides a powerful tool to manipulate light at the nanoscale, below the diffraction limit. Thus, plasmons have become of paramount importance for a wide range of applications [6][7][8] spanning from light harvesting[9] to biosensing [10]. In general terms, plasmons can be defined as electronic collective excitations that arise when the Coulomb interaction between excited states is switched on [11]. However, their theoretical description at the microscopic level is still an open and controversial issue [12]. In large nanoparticles optical and plasmonic properties are generally described by electrodynamics of continuous media, exploiting semiclassical models of the frequencydependent dielectric function [13][14][15] and the identification of plasmons is straightforward. This description has been very useful for designing applications, but fails to convey a microscopic understanding of what plasmons are. Nanoparticles and their excitations are composed of electrons and nuclei like ordinary molecules. Therefore, it must be possible to understand their excited states, including plasmons, in terms of the same elementary electron and hole excitations routinely used to interpret molecular excited states. Notably, such a microscopic description is mandatory when the system size reaches 1-2 nanometers, where the dielectric description breaks down and quantum finite-size effects [2,16] as well as the details of the atomic structure[17] play a crucial role. However, at the nanoscale, single-particle and plasmonic excitations are intrinsically mixed [18], and how to recognize a plasmonic excitation is still an unsolved problem.A few approaches have been recently proposed attempting to classify the plasmonic character of the excitations of nanosystems. [11,[19][20][21][22][23][24] In particular, Bernadotte et al. [11] formulated, in the framework of tim...

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“…It can therefore be concluded that the HOMO and LUMO continue to constitute the predominantly involved single-particle states in the formation of this resonance also in the interacting system. More detailed investigations concerning this issue have been performed and similar conclusions have been drawn in the context of non-interacting and interacting molecular chains in a TB framework [65], in time-dependent density functional theory [19], and upon exact diagonalization [66], as well as in metallic gold nanospheres [66,70], and in structured nanographene [71]. On the other hand, Figs.…”

Section: Interacting Hybrid Systemmentioning

confidence: 54%

“…For the latter two insulating structures, the non-interacting absorption cross section is a valid approximation to the fully interacting system. charge carrier oscillations plays a significant role for determining resonant modes [19,[64][65][66][67][68][69]. To elucidate this, we show the absorption spectra of all three stand-alone structures in Fig.…”

Section: Interacting Hybrid Systemmentioning

confidence: 99%

Modification of the Optical Properties of Molecular Chains upon Coupling to Adatoms

Müller,

Kosik,

Pelc

et al. 2021

Preprint

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Adsorbed atoms (adatoms) coupled to the matrix of solid state host materials as impurities can significantly modify their properties. Especially in low-dimensional materials, such as one-dimensional organic polymer chains or quasi-one-dimensional graphene nanoribbons, intriguing manipulation of the optical properties, such as the absorption cross section, is possible. The most widely used approach to couple quantum emitters to optical antennas is based on the Purcell effect. This formalism, however, does not comprise charge transfer from the emitter to the antenna, but only spontaneous emission of the quantum emitter into the tailored photonic environment, that is evoked by the antenna. To capture such effects, we present a tight-binding formalism to couple an adatom to a finite Su-Schrieffer-Heeger chain, where the former is treated as a two-level system and the latter acts as an optical antenna. We systematically analyze how the coupling strength and the position of the adatom influence the optical properties of the molecular chains in the model. We take into account charge transfer from the adatom to the antenna and vice versa via an inter-system hopping parameter, and also include Coulomb interaction within the antenna as well as between the adatom and the antenna. We show that coupling the adatom to one of the bulk atoms of the linear chain results in a substantial change in optical properties already for comparatively small coupling strengths. We also find that the position of the adatom crucially determines if and how the optical properties of the chains are altered. Therefore, we identify this adatom-chain hybrid system as a tunable platform for light-matter interaction at the nanoscale.I.

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Approaching the quantum limit for nanoplasmonics

Cited by 11 publications

References 55 publications

How To Identify Plasmons from the Optical Response of Nanostructures

How To Identify Plasmons from the Optical Response of Nanostructures

Quantifying the Plasmonic Character of Optical Excitations in Nanostructures

Modification of the Optical Properties of Molecular Chains upon Coupling to Adatoms

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