Field Emission of Electrons Generated by the Near Field of Strongly Coupled Plasmons

Schertz, F.; Schmelzeisen, Marcus; Kreiter, Maximilian; Elmers, H. J.; Schönhense, G.

doi:10.1103/physrevlett.108.237602

Cited by 64 publications

(71 citation statements)

References 29 publications

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“…Regarding the mechanism of the nonlinear photoemission, it is also worth noting that field emission is possible as argued in a recent report. 45 The field emission occurs at the lowfrequency/high-intensity limit of the electric field induced by the electron ejection and is thus referred to as a tunneling emission. The laser intensity used in this study was typically on the order of 10 MW cm 22 .…”

Section: Resultsmentioning

confidence: 99%

Direct imaging of the near field and dynamics of surface plasmon resonance on gold nanostructures using photoemission electron microscopy

et al. 2013

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Localized surface plasmon resonance (LSPR) can be supported by metallic nanoparticles and engineered nanostructures. An understanding of the spatially resolved near-field properties and dynamics of LSPR is important, but remains experimentally challenging. We report experimental studies toward this aim using photoemission electron microscopy (PEEM) with high spatial resolution of sub-10 nm. Various engineered gold nanostructure arrays (such as rods, nanodisk-like particles and dimers) are investigated via PEEM using near-infrared (NIR) femtosecond laser pulses as the excitation source. When the LSPR wavelengths overlap the spectrum of the femtosecond pulses, the LSPR is efficiently excited and promotes multiphoton photoemission, which is correlated with the local intensity of the metallic nanoparticles in the near field. Thus, the local field distribution of the LSPR on different Au nanostructures can be directly explored and discussed using the PEEM images. In addition, the dynamics of the LSPR is studied by combining interferometric time-resolved pump-probe technique and PEEM. Detailed information on the oscillation and dephasing of the LSPR field can be obtained. The results identify PEEM as a powerful tool for accessing the near-field mapping and dynamic properties of plasmonic nanostructures. Keywords: femtosecond laser; local field enhancement; near-field imaging; photoemission electron microscopy; surface plasmon resonance INTRODUCTION Because of the rapid development of nanofabrication techniques, metallic nanostructures that can exhibit localized surface plasmon resonance (LSPR) can be fabricated using several methods. The resonance frequency and amplitude of LSPR on metallic nanostructures are known to depend on the metal materials, shapes, and surrounding media. [1][2][3][4] In addition, the LSPR can confine optical fields in nanoscale space, leading to the so-called local field enhancement effect. These unique properties promote the application of LSPR in many fields, such as surface-enhanced Raman scattering, 5-8 sensing, 1,9,10 plasmonassisted photochemical reactions 4,11,12 and photocurrent generation. [13][14][15] To further understand the LSPR mechanism and to optimize the design of the plasmonic nanostructures for most applications, the near-field properties of the LSPR fields (especially the near-field distribution of the plasmonic nanostructures) must be determined. To date, investigations of the optical properties of LSPR have largely relied on far-field spectroscopic techniques or numerical simulations. Several experimental approaches have been utilized to visualize the near field, including scanning photoionization microscopy, 16,17 scanning near-field optical microscopy, 18-21 nonlinear luminescence or fluorescent microscopy, 22,23 nonlinear photopolymerization 24,25 and near-field ablation of a substrate. [26][27][28][29] However, these approaches have

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Section: Resultsmentioning

confidence: 99%

Direct imaging of the near field and dynamics of surface plasmon resonance on gold nanostructures using photoemission electron microscopy

et al. 2013

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“…Analysis of the data yields peak values up to 45 μA. Combined with an effective cross-section of ∼80 nm 2 (Fig. 3b,c), we obtain sub-cycle current densities exceeding 50 MA cm -2 , driven at room temperature and without damaging the device.…”

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confidence: 88%

“…The high peak electric fields provided by single-cycle light pulses can be harnessed to manipulate and control charge motion in solid-state systems, resulting in electron emission out of metals and semiconductors [1][2][3][4][5][6] or high harmonics generation in dielectrics 7,8 . These processes are of a non-perturbative character and require precise reproducibility of the electric-field profile [9][10][11][12][13][14] .…”

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Sub-cycle optical phase control of nanotunnelling in the single-electron regime

et al. 2016

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The high peak electric fields provided by single-cycle light pulses can be harnessed to manipulate and control charge motion in solid-state systems, resulting in electron emission out of metals and semiconductors [1][2][3][4][5][6] or high harmonics generation in dielectrics 7,8 . These processes are of a non-perturbative character and require precise reproducibility of the electric-field profile 9-14 . Here, we vary the carrier-envelope phase of 6-fs-long near-infrared pulses with pJ-level energy to control electronic transport in a laterally confined nanoantenna with an 8 nm gap. Peak current densities of 50 MA cm -2 are achieved, corresponding to the transfer of individual electrons in a half-cycle period of 2 fs. The observed behaviours are made possible by the strong distortion of the effective tunnelling barrier due to the extreme electric fields that the nanostructure provides and sustains under sub-cycle optical biasing. Operating at room temperature and in a standard atmosphere, the performed experiments demonstrate a robust class of nanoelectronic switches gated by phase-locked optical transients of minute energy content.Present-day high-frequency devices operate in the microwave range, but direct control of electron flow by the electric-field profile of few-cycle optical pulses has recently been demonstrated 12,15 . These experiments were based on strong perturbation of the electronic system in a dielectric material, resulting in a large incoherent background current. Nanoscale confinement of the region biased by the optical transient might avoid a significant influence of nonlinear conductivity in an insulating substrate and result in purely coherent tunnelling currents 16 that may be controlled by the precise shape of the electric field cycles. Our approach to reaching this goal is illustrated in the upper part of Fig. 1a. A single-cycle near-infrared pulse (left) is focused to a nanoscale junction of an electronic circuit (centre) with nonlinear and antisymmetric current-voltage (I-V) characteristics (right). An effective bias then arises when the exciting electric field is cosine-shaped (blue transient and blue dot in the I-V scheme) because its extremum occurs only for one polarity. Consequently, the symmetry of electronic transport is broken, even when integrating over the entire transient, and a net tunnelling current of electrons results through the potential barrier represented by the free-space gap (Fig. 1b,c). Our experiment favours tunnelling over other phenomena such as multiphoton ionization 4 by operating with ultrashort pulses and extreme nanoconfinement of the electric field. No background current exists when the control field is sineshaped (red transient and dot in the I-V characteristics, respectively), because positive and negative polarities now have precisely opposite effects. Consequently, the total current amplitude and direction may be set by varying the carrier-envelope phase (CEP), Δφ CEP , of the pulse. Owing to the single-cycle pulse duration, nanoscale constriction and fi...

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“…In the experiments reported in this paper, we estimate the peak intensity incident on the sample to be on the order of 5*10 9 W/cm 2 . Compared to previous PEEM studies using 800 nm light, this intensity is in the high part of the reported ranges [11][12][13], which is expected due to the lower photon energy. The laser beam is s-polarized, i.e.…”

Section: Methodsmentioning

confidence: 81%

“…This further implies that the intensities required for imaging are likely to be beyond the perturbative regime of direct n-photon photoemission via virtual states. Other mechanisms such as field emission [13], thermal emission [24], and defect-mediated emission [25], as well as combinations of the above [26], have been proposed to generate electron emission by optical pulses. Regardless of the exact mechanism involved, the laser-induced emission of an electron from Ag will due to energy conservation require at least six 0.8 eV photons, and the photoelectron yield is expected to depend non-linearly on the local near-field intensity.…”

mentioning

confidence: 99%

Photoemission electron microscopy of localized surface plasmons in silver nanostructures at telecommunication wavelengths

Mårsell

Larsen

Arnold

et al. 2015

Journal of Applied Physics

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Field Emission of Electrons Generated by the Near Field of Strongly Coupled Plasmons

Cited by 64 publications

References 29 publications

Direct imaging of the near field and dynamics of surface plasmon resonance on gold nanostructures using photoemission electron microscopy

Direct imaging of the near field and dynamics of surface plasmon resonance on gold nanostructures using photoemission electron microscopy

Sub-cycle optical phase control of nanotunnelling in the single-electron regime

Photoemission electron microscopy of localized surface plasmons in silver nanostructures at telecommunication wavelengths

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