Quantum Plasmonics: Optical Properties and Tunability of Metallic Nanorods

Zuloaga, Jorge; Prodan, Emil; Nordlander, Peter

doi:10.1021/nn101589n

Cited by 229 publications

(233 citation statements)

References 43 publications

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“…Hence, Q does not seem to scale with structure size, as hypothesized in Ref. [11]. However, there is still the possibility of quantum plasmonic effects on a larger scale within the error bars of our results.…”

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confidence: 61%

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Probing of Optical Near-Fields by Electron Rescattering on the 1 nm Scale

et al. 2013

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We present a new method of measuring optical near-fields within ∼1 nm of a metal surface, based on rescattering of photoemitted electrons. With this method, we precisely measure the field enhancement factor for tungsten and gold nanotips as a function of tip radius. The agreement with Maxwell simulations is very good. Further simulations yield a field enhancement map for all materials, which shows that optical near-fields at nanotips are governed by a geometric effect under most conditions, while plasmon resonances play only a minor role. Last, we consider the implications of our results on quantum mechanical effects near the surface of nanostructures and discuss features of quantum plasmonics.The excitation of enhanced optical near-fields at nanostructures allows the localization of electromagnetic energy on the nanoscale [1,2]. At nanotips, this effect has enabled a variety of applications, most prominent amongst them are scanning near-field optical microscopy (SNOM) [3][4][5][6][7], which has reached a resolving power of 8 nm [8], and tip-enhanced Raman spectroscopy (TERS) [3,9]. Because of the intrinsic nanometric length scale, measuring and simulating the tips' near-field has proven hard and led to considerably diverging results (see Refs. [1,7] for overviews). Here we demonstrate a nanometric field sensor based on electron rescattering, a phenomenon well known from attosecond science [10]. It allows measurement of optical near-fields, integrating over only 1 nm right at the structure surface, close to the length scale where quantum mechanical effects become relevant [11][12][13][14][15]. Hence, this method measures near-fields on a scale that is currently inaccessible to other techniques (such as SNOM or plasmonic methods in electron microscopy [16][17][18]), and reaches down to the minimum length scale where one can meaningfully speak about a classical field enhancement factor. In the future, the method will allow tomographic reconstruction of the optical near-field and potentially the sensing of fields in more complex geometries such as bow-tie or split-ring antennas.In general, three effects contribute to the enhancement of optical electric fields at structures that are smaller than the driving wavelength [7,[20][21][22]. The first effect is geometric in nature, similar to the electrostatic lightning rod effect: the discontinuity of the electric field at the material boundary and the corresponding accumulation of surface charges lead to an enhanced near-field at any sharp protrusion or edge. This effect causes singularities in the electric field at ideal edges of perfect conductors. For real materials at optical frequencies, the electric field is not as strongly enhanced and remains finite [23]. The second effect occurs at structures whose size is an odd multiple of half the driving wavelength: optical antenna resonances can be observed there. The third effect concerns only plasmonic materials like gold and silver, where an enhanced electric field can arise due to a localized surface plasmon resonance. ...

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confidence: 61%

“…If Q ≈ L as in Ref. [11], the maximum of the near-field is significantly reduced, which implies a corresponding reduction of the cut-off energy. Extremely sharp nanostructures (R ≲ 3 nm) will be required to reach this regime if Q does not scale with structure size.…”

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confidence: 67%

Probing of Optical Near-Fields by Electron Rescattering on the 1 nm Scale

et al. 2013

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“…Despite its simplicity, the JM captures the collective plasmonic modes of the conduction electrons at the surface in individual nanoparticles and nanoparticle dimers. 56,59,60,92 The JM has also been successfully used to model effects associated with conduction electrons in a variety of metallic systems such as in electronic and optical properties of metal clusters and surfaces, [93][94][95][96] charge transfer reactions between atoms and surfaces, 97 conductances of molecular junctions, 98 and strong-eld effects. 99 The second part of this section will discuss the basis of the QCM, i.e., how to incorporate the optical conductivity derived from a quantum mechanical calculation into the classical calculations of the plasmonic response (Subsection 2.3).…”

Section: Implementation Of the Local Qcmmentioning

confidence: 99%

A classical treatment of optical tunneling in plasmonic gaps: extending the quantum corrected model to practical situations

et al. 2015

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(2015). A classical treatment of optical tunneling in plasmonic gaps: extending the quantum corrected model to practical situations. Faraday Discussions, 178, The optical response of plasmonic nanogaps is challenging to address when the separation between the two nanoparticles forming the gap is reduced to a few nanometers or even subnanometer distances. We have compared results of the plasmon response within different levels of approximation, and identified a classical local regime, a nonlocal regime and a quantum regime of interaction. For separations of a fewÅngstroms, in the quantum regime, optical tunneling can occur, strongly modifying the optics of the nanogap. We have considered a classical effective model, so called Quantum Corrected Model (QCM), that has been introduced to correctly describe the main features of optical transport in plasmonic nanogaps. The basics of this model are explained in detail, and its implementation is extended to include nonlocal effects and address practical situations involving different materials and temperatures of operation.

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“…3f, the electric field at point 1 is calculated to be 1,000 times larger than the field of the incident light, although the use of the classical method at these small interparticle separations may overestimate the enhancement. 31 It is interesting to analyse the modes of the 3D symmetric tetramer. The surface charge distributions in spheres 4 and 3 (partly blocked) of Fig.…”

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confidence: 99%

The surface plasmon modes of self-assembled gold nanocrystals

et al. 2012

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The three-dimensional (3D) self-assembly of nanocrystals constitutes one of the most important challenges in materials science. A key milestone is the synthesis of simple, regular structures, such as platonic solids, composed of nanocrystal building blocks. Such objects are predicted to have unique optical and electronic properties such as polarization-independent light-scattering and intense local fields. Here we present a two-stage process for fabricating well-defined and highly symmetric, 3D gold nanocrystal structures, including tetrahedra, 3D pentamers and 3D hexamers. Polarized scattering spectra are used to elucidate the plasmon modes present in each structure, and these are compared with computational models. We conclude that self-assembly of highly symmetric, polarization-independent structures with interparticle spacings of order 0.5 nm can now be fabricated. Drastically, enhanced local fields, 1000 times higher than the incident field strength, are produced within the interstices. Fano resonances are generated if the symmetry is broken.

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Quantum Plasmonics: Optical Properties and Tunability of Metallic Nanorods

Cited by 229 publications

References 43 publications

Probing of Optical Near-Fields by Electron Rescattering on the 1 nm Scale

Probing of Optical Near-Fields by Electron Rescattering on the 1 nm Scale

A classical treatment of optical tunneling in plasmonic gaps: extending the quantum corrected model to practical situations

The surface plasmon modes of self-assembled gold nanocrystals

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