Electron rescattering at metal nanotips induced by ultrashort laser pulses

Wachter, Georg; Lemell, C.; Burgdörfer, Joachim; Schenk, Markus; Krüger, Michael; Hommelhoff, Peter

doi:10.1103/physrevb.86.035402

Cited by 79 publications

(95 citation statements)

References 28 publications

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“…Very recently, it has been observed that part of the electrons can be driven back to the parent tip within a single cycle of the optical field. There, the electrons can scatter elastically and gain more energy in the optical field [14,[30][31][32]. This process, well known from atomic physics [10,33,34], has been called rescattering and leads to pronounced spectral features that are sensitive to the local electric field.…”

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confidence: 99%

“…At small energies, such spectra display an exponential decrease in count rate, followed by a plateau towards larger energies. The latter is an indication of electron rescattering [14,30,34,36,37]. This process has found utmost attention as it is at the core of attosecond science [10].…”

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confidence: 99%

“…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.…”

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

et al. 2013

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“…[20,21] for field-enhancement and near-field effects). Several models have been recently developed and applied in order to understand the experimental data and to guide future measurements [22][23][24][25]. Furthermore, it has been demonstrated that solid state samples can also be used as a generators of high order harmonic radiation, although the HHG phenomenon using bulk matter is at its very beginning, both theoretically and experimentally [26,27].…”

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High-order-harmonic generation driven by metal nanotip photoemission: Theory and simulations

et al. 2014

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We present theoretical predictions of high-order harmonic generation (HHG) resulting from the interaction of short femtosecond laser pulses with metal nanotips. It has been demonstrated that high energy electrons can be generated using nanotips as sources; furthermore the recollision mechanism has been proven to be the physical mechanism behind this photoemission. If recollision exists, it should be possible to convert the laser-gained energy by the electron in the continuum in a high energy photon. Consequently the emission of harmonic radiation appears to be viable, although it has not been experimentally demonstrated hitherto. We employ a quantum mechanical time dependent approach to model the electron dipole moment including both the laser experimental conditions and the bulk matter properties. The use of metal tips shall pave a new way of generating coherent XUV light with a femtosecond laser field.

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“…In order to unmask the effects that take place at a metal surface, we have invoked a model applicable to metals: we employ a 1-dimensional time-dependent density functional theory (TDDFT) quantum simulation. Details of the model are given in [6,7], results are shown in Fig. 2.…”

Section: Rescattering At a Tipmentioning

confidence: 99%