Quantum Plasmon Resonances Controlled by Molecular Tunnel Junctions

Tan, Shu Fen; Wu, Lin; Yang, Joel K. W.; Bai, Peng; Bosman, Michel; Nijhuis, Christian A.

doi:10.1126/science.1248797

Cited by 404 publications

(507 citation statements)

References 40 publications

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“…Notably, the decay length ' c takes similar values for the three noble metals, but it is noticeably larger for Na. For systems separated by water or dielectrics, 53 we also expect to nd signicantly larger ' c values.…”

Section: Faraday Discussionmentioning

confidence: 94%

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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Section: Faraday Discussionmentioning

confidence: 94%

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

et al. 2015

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“…Significant differences in the influence of charge transfer on the modal structure of charge transfer plasmons are found in this case, a situation that needs to be considered when interpreting molecular transport experiments dealing with the quantum regime. 29 The cavity modes can be supported by any plasmonic junction with flat faces, assuming that the lateral dimensions of the cavity are comparable to the plasmonic wavelength in the gap and that the separation distance is relatively small. For nearly flat gaps, even small variations of the gap separation across the faces may suppress the formation of these modes or confine them to particular regions of the gap.…”

Section: ■ Summary and Discussionmentioning

confidence: 99%

The Morphology of Narrow Gaps Modifies the Plasmonic Response

et al. 2015

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ABSTRACT:The optical response of a plasmonic gapantenna is mainly determined by the Coulomb interaction of the two constituent arms of the antenna. Using rigorous calculations supported by simple analytical models, we observe how the morphology of a nanometric gap separating two metallic rods dramatically modifies the plasmonic response. In the case of rounded terminations at the gap, a conventional set of bonding modes is found that red-shifts strongly with decreasing separation. However, in the case of flat surfaces, a distinctly different situation is found with the appearance of two sets of modes: (i) strongly radiating longitudinal antenna plasmons (LAPs), which exhibit a red-shift that saturates for very narrow gaps, and (ii) transverse cavity plasmons (TCPs) confined to the gap, which are weakly radiative and strongly dependent on the separation distance between the two arms. The two sets of modes can be independently tuned, providing detailed control of both the near-and far-field response of the antenna. We illustrate these properties also with an application to larger infrared gap-antennas made of polar materials such as SiC. Finally we use the quantum corrected model (QCM) to show that the morphology of the gap has a dramatic influence on the plasmonic response also for subnanometer gaps. This effect can be crucial for the correct interpretation of charge transfer processes in metallic cavities where quantum effects such as electron tunneling are important. KEYWORDS: optical antennas, plasmonic gaps, cavity modes, antenna modes, quantum effects, quantum corrected model, plasmonic resonances, phononic resonances M etallic particles can show a strong optical response due to the excitation of resonant plasmonic modes, making light manipulation possible in structures of dimensions comparable to or smaller than the wavelength. Typical effects are the efficient emission of radiation and the concentration of the incoming light energy in small volumes, thus justifying the characterization of these metallic structures as optical antennas. 1,2 Modifications of the geometry, size, or materials 3−6 affect the optical response. In particular, the resonant modes of optical antennas consisting of two metallic particles separated by a narrow gap show significant sensitivity to the properties of the gap. 7−19 In an optical antenna, a change in geometry can simultaneously affect both the strength and wavelength of its resonances and modify both the far-and near-field response. It is usually a challenge, for example, to control the near field without affecting the far-field properties. In this theoretical work, we discuss how the coexistence 20,21 of two different and mostly spectrally decoupled types of modes in flat-gap antennas, namely, transverse cavity modes 22 and longitudinal antenna modes, 15 allows for a more flexible tuning of far-and near-field properties compared to that of the conventional spherical-gap terminations 13,17,23 The importance of the gap morphology 24 is particularly pronounced for nanometer-...

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“…21 The ability to spatially resolve highly localized plasmon resonances using STEM-EELS has provided experimental evidence for the size and shape dependence of the LSP response of individual particles, 21,25 the excitation of multipole modes in larger particles, 26 and the hybridized plasmonic response of interacting plasmonic nanoparticles, 23,24,27 to name a few applications. EELS can also provide valuable information about current-carrying quantum plasmons, namely charge transfer plasmons, 28 and ultrasmall plasmonic nanoparticles. 29 Additional advantages of using STEM-EELS to probe the plasmonic response of sub-wavelength metal nanoparticles include: (i) the technique's ability to provide information from the interior of the sample as signals are collected in transmission, (ii) the possibility of manipulating interparticle distances with the electron beam, 26 and (iii) the possibility to take advantage of the many analytical capabilities (imaging, diffraction, chemical characterization by EEL and energy-dispersive X-ray spectroscopies) that are available in a STEM instrument.…”

Section: Imaging Surface Plasmons With Electron Energy Loss Spectroscopymentioning

confidence: 99%

Visualizing surface plasmons with photons, photoelectrons, and electrons

El‐Khoury

Abellán

Gong

et al. 2016

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Both photons and electrons may be used to excite surface plasmon polaritons, the collective charge density fluctuations at the surface of metal nanostructures. By virtue of their nanoscopic and dissipative nature, a detailed characterization of surface plasmon (SP) eigenmodes in real space-time ultimately requires joint nanometer spatial and femtosecond temporal resolution.The latter realization has driven significant developments in the past few years, aimed at interrogating both localized and propagating SP modes. In this mini-review, we briefly highlight different techniques employed by our own groups to visualize the enhanced electric fields associated with SPs. Specifically, we discuss recent hyperspectral optical microscopy, tipenhanced Raman nano-spectroscopy, nonlinear photoemission electron microscopy, as well as correlated scanning transmission electron microscopy-electron energy loss spectroscopy measurements targeting prototypical plasmonic nanostructures and constructs. Through selected practical examples from our own laboratories, we examine the information content in multidimensional images recorded by taking advantage of each of the aforementioned techniques. In effect, we illustrate how SPs can be visualized at the ultimate limits of space and time.

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Quantum Plasmon Resonances Controlled by Molecular Tunnel Junctions

Cited by 404 publications

References 40 publications

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

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

The Morphology of Narrow Gaps Modifies the Plasmonic Response

Visualizing surface plasmons with photons, photoelectrons, and electrons

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