Attosecond physics phenomena at nanometric tips

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

doi:10.1088/1361-6455/aac6ac

Cited by 112 publications

(111 citation statements)

References 297 publications

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“…In order to show that MPP takes place, we measure the laser power dependence of the electron beam current j n . An n-th order MPP-emission process scales with the laser intensity I as j n ∼ I n [11,18,31,32]. Fig.…”

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confidence: 99%

High spatial coherence in multiphoton-photoemitted electron beams

Meier

Higuchi

Nutz

et al. 2018

Applied Physics Letters

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Nanometer-sharp metallic tips are known to be excellent electron emitters. They are used in highest-resolution electron microscopes in cold field emission mode to generate the most coherent electron beam in continuous-wave operation. For time-resolved operation, sharp metal needle tips have recently been triggered with femtosecond laser pulses. We show here that electrons emitted with near-infrared femtosecond laser pulses at laser oscillator repetition rates show the same spatial coherence properties as electrons in cold field emission mode in cw operation. From electron interference fringes, obtained with the help of a carbon nanotube biprism beam splitter, we deduce a virtual source size of less than (0.65 ± 0.06) nm for both operation modes, a factor of ten smaller than the geometrical source size. These results bear promise for ultrafast electron diffraction, ultrafast electron microscopy and other techniques relying on highly coherent and ultrafast electron beams. The corresponding Applied Physics Letters paper is available at: https://doi.org/10.1063/1.5045282.The ability of electrons to interfere, given by their coherence properties, enables matter wave experiments with electrons, such as diffraction, interference or electron holography, as well as highest resolution microscopy [1]. These techniques all rely on highly coherent electron sources. In recent years, great efforts have been undertaken to equip these techniques also with high temporal resolution. Applications like ultrafast electron diffraction [2,3] or ultrafast electron microscopy [4,5] are only a few examples. Spatially coherent and ultrafast pulsed electron sources are required for these applications. Lasertriggered electron sources such as flat photocathodes have been employed. More recently, electron emission with high spatial coherence and high temporal resolution down to femtosecond timescales has been reached by triggering the emission from a metallic nanotip with ultrashort laser pulses [6][7][8][9][10][11][12][13][14][15][16][17][18]. Even sub-femtosecond control has been shown using the carrier-envelope phase of the exciting few-cycle laser pulse [12,19]. Besides the fundamental investigations on this topic, ultrafast electron beams from needle tips have been already used in initial experiments [20,21]. In both cases, a sample is optically pumped with a femtosecond optical pulse and then probed with an ultrashort electron pulse, generated from a second femtosecond optical pulse focused on a metallic nanotip. However both experiments rather rely on a particle projection image of the electron beam and do not seem to take advantage of the electrons' coherence yet. For completeness, we mention a low-energy electron diffraction experiment that does take advantage of electron coherence, but there longer timescales, quite com- * stefan.m.meier@fau.de † peter.hommelhoff@fau.de plex electron optics and likely a filtered electron beam have been employed [15]. For forthcoming experiments on ultrafast electron diffraction or holography, it is hi...

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confidence: 99%

High spatial coherence in multiphoton-photoemitted electron beams

Meier

Higuchi

Nutz

et al. 2018

Applied Physics Letters

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“…The sub-cycle emission and its motion near the metal nanostructures have been successfully analyzed using standard approaches such as the semi-classical calculation, the quantum mechanical calculation of electron wavepacket, and the first-principle calculation. In strong-field regime, the semi-classical approach (referred to as Simpleman model) has been widely adopted; the emission yield and its dynamics are calculated separately [56,60,80]. To calculate the emission yield, Fowler-Nordheim formalism is applied with respect to the time-varying laser field.…”

Section: A Dynamic Motion Of Electrons Near Metallic Nanostructuresmentioning

confidence: 99%

Ultrashort field emission in metallic nanostructures and low-dimensional carbon materials

Park

Ahn

2020

Advances in Physics: X

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This study investigates recent advances in photoelectron emission generated by irradiating ultrashort lasers on metallic nanostructures and low-dimensional carbon materials. Recently, primary focus has been on improving the efficiency of emitters, i.e. increasing the number of field-emitted electrons and their respective kinetic energies. An example of this is the modification of the conventional metal nanotip through adiabatic nanofocusing and various plasmonic metal structures, such as nanorods and bowtie antenna. The coherent emission control with two color irradiation enabled modulation in the emission yield. In addition, THz waves near the metallic nanostructure induced a highly accelerated, monochromatic energy. Alternative to metallic nanotips, carbon nanotubes are emerging as efficient photoelectron emitters, due to the large enhancement factor associated with their high aspect ratio and damage threshold. They particularly allowed the use of femtosecond light sources with a relatively short wavelength, resulting in the generation of photoelectrons with a narrow bandwidth. Additionally, electronic control over the singlewalled nanotubes band structure added a degree of freedom for controlling the electron emission yield. Finally, we review the strong-field tunneling emission in graphene edge, with the emission yield showing an anomalous increase of nonlinear order, corresponding to the deep strong tunneling regime.

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“…These processes have been studied extensively in the atomic, or gas, regime ( [4,5] for instance), and increasing interest has begun to surround metallic emitters. In the case of bulk metal emitters, experiments and numerical studies have been performed with metallic nanotips in order to achieve high enhancement fields [6]. However, these nano-scale tips are prone to damage and are limited by their point-sized emission surface.…”

Section: Introductionmentioning

confidence: 99%

“…These benefits combined permit high brightness electron beam production from cold, durable photocathodes manufactured using standard etching and deposition processes. Previously, simulations have been performed with incident fields upwards of 50 GV/m for gas-based high harmonic generation (HHG) [7] and with time-dependent density functional theory (TD-DFT) for the metallic tip rescatter process [6]. However, works analyzing the light-metal interaction keep to modest peak fields and do not include important physical factors including field dropoff [8,9] and field penetration into the metal.…”

Section: Introductionmentioning

confidence: 99%

1D Quantum Simulations of Electron Rescattering with Metallic Nanoblades

2019

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Electron rescattering has been well studied and simulated for cases with ponderomotive energies of the quasi-free electrons, derived from laser–gas and laser–surface interactions, lower than 50 eV. However, with advents in longer wavelengths and laser field enhancement metallic surfaces, previous simulations no longer suffice to describe more recent strong field and high yield experiments. We present a brief introduction to and some of the theoretical and empirical background of electron rescattering emissions from a metal. We set upon using the Jellium potential with a shielded atomic surface potential to model the metal. We then explore how the electron energy spectra are obtained in the quantum simulation, which is performed using a custom computationally intensive time-dependent Schrödinger equation solver via the Crank–Nicolson method. Finally, we discuss the results of the simulation and examine the effects of the incident laser’s wavelength, peak electric field strength, and field penetration on electron spectra and yields. Future simulations will investigate a more accurate density functional theory metallic model with a system of several non-interacting electrons. Eventually, we will move to a full time-dependent density functional theory approach.

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Attosecond physics phenomena at nanometric tips

Cited by 112 publications

References 297 publications

High spatial coherence in multiphoton-photoemitted electron beams

High spatial coherence in multiphoton-photoemitted electron beams

Ultrashort field emission in metallic nanostructures and low-dimensional carbon materials

1D Quantum Simulations of Electron Rescattering with Metallic Nanoblades

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