Electron source brightness and degeneracy from Fresnel fringes in field emission point projection microscopy

Spence, J. C. H.; Qian, W.; Silverman, Mark P.

doi:10.1116/1.579166

Cited by 75 publications

(40 citation statements)

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“…Finally, temporal lenses have the potential to increase by orders of magnitude the quantum degeneracy of an electron packet (33). The first use of electron quantum degeneracy in free space-the demonstration of the Hanbury Brown and Twiss effect for electrons (antibunching)-reached a degeneracy value of 10 Ϫ4 (34,35) and in other sources could be 10 Ϫ6 or less.…”

Section: Discussionmentioning

confidence: 99%

Temporal lenses for attosecond and femtosecond electron pulses

Hilbert

Uiterwaal

Barwick

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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Here, we describe the ''temporal lens'' concept that can be used for the focus and magnification of ultrashort electron packets in the time domain. The temporal lenses are created by appropriately synthesizing optical pulses that interact with electrons through the ponderomotive force. With such an arrangement, a temporal lens equation with a form identical to that of conventional light optics is derived. The analog of ray diagrams, but for electrons, are constructed to help the visualization of the process of compressing electron packets. It is shown that such temporal lenses not only compensate for electron pulse broadening due to velocity dispersion but also allow compression of the packets to durations much shorter than their initial widths. With these capabilities, ultrafast electron diffraction and microscopy can be extended to new domains,and, just as importantly, electron pulses can be delivered directly on an ultrafast techniques target specimen.attosecond imaging ͉ ultrafast techniques W ith electrons, progress has recently been made in imaging structural dynamics with ultrashort time resolution in both microscopy and diffraction (ref. 1 and references therein). Earlier, nuclear motions in chemical reactions were shown to be resolvable on the femtosecond (fs) time scale using pulses of laser light (ref. 2 and references therein), and the recent achievement of attosecond (as) light pulses (for recent reviews, see refs. 3-6) has opened up this temporal regime for possible mapping of electron dynamics. Electron pulses of femtosecond and attosecond duration, if achievable, are powerful tools in imaging. The ''electron recombination'' techniques used to generate such attosecond electron pulses require the probing electron to be created from the parent ions (to date no attosecond electron pulses have been delivered on an arbitrary target) and for general applications it is essential that the electron pulse be delivered directly to the specimen.In ultrafast electron microscopy (UEM) (7), the electron packet duration is determined by the initiating laser pulse, the dispersion of the electron packet due to an initial energy spread and electron-electron interactions (see, e.g., ref. 8). Because packets with a single electron can be used to image (1, 7), and the initiating laser pulse can in principle be made very short (Ͻ10 fs), the limiting factor for the electron pulse duration is the initial energy spread. In photoelectron sources this spread is primarily due to the excess energy above the work function of the cathode (8), and is inherent to both traditional photocathode sources (9) and optically induced field emission sources (10-13). Energytime uncertainty will also cause a measurable broadening of the electron energy spread, when the initiating laser pulse is decreased below Ϸ10 fs. For ultrafast imaging techniques to be advanced into the attosecond temporal regime, methods for dispersion compensation and new techniques to further compress electron pulses to the attosecond regime need to be developed.A rec...

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Section: Discussionmentioning

confidence: 99%

Temporal lenses for attosecond and femtosecond electron pulses

Hilbert

Uiterwaal

Barwick

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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“…They have some unique electron optics properties quite different from the conventional FE sources, as described below. First, the brightness of the e-beams is high for low kinetic energies [1]. Second, the transverse coherency is also high because of extremely narrow emission areas, giving rise to good interference characteristics for low emission exposure [1,2].…”

Section: Introductionmentioning

confidence: 99%

Ballistic Field Electron Emission from Demountable Single Atom Tip

Rokuta

Itagaki

Nomura

et al. 2006

2006 International Symposium on Discharges and Electrical Insulation in Vacuum

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Highly coherent electron emitter is an attractive research subject in nanotechnology. In our group, novel field electron tips of which the entire dimensions are approximately a few nanometers were grown on the apex of the W tip. Owing to thermodynamically stable structures of the nanotips, the equivalent atomic structures were repeatedly reproduced merely by annealing at moderate temperatures. Furthermore, they were found to retrieve the pristine field emission properties. These characteristics, also regarded the "self-reparing function" and "demountable property", respectively, are important for the practical application. In this talk, the structural sample-fabrication procedures, the results of the endurance (destruction-and-regeneration) tests, and the experimental data of the field electron microscopy (FEM), field ion microscopy, and spectroscopy (FES) of the nanotip are shown.. As a result, peculiar emission processes are clarified.

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“…In-line holographic imaging of individual biological specimen with 1 nm spatial resolution at the anode has been realized recently [20,52] by using graphene [19] as sample support, thus reducing the biprism effect which is detrimental if high spatial resolution is desired [53]. Beyond such sample restrictions, the spatial resolution of femtosecond in-line holography will ultimately be determined by the spatial coherence of the electron source, which is given by the effective source size r eff and the electron energy spread [54]. While the transverse coherence properties of ultrashort electron wave packets emitted from nanotips have not yet been thoroughly investigated, an effective source size of < 1 nm comparable with values for DC field emission was found for linear photoemission from tungsten tips [13].…”

Section: Resultsmentioning

confidence: 99%

Nanofocused Plasmon-Driven Sub-10 fs Electron Point Source

et al. 2016

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Progress in ultrafast electron microscopy relies on the development of efficient laser-driven electron sources delivering femtosecond electron pulses to the sample. In particular, recent advances employ photoemission from metal nanotips as coherent point-like femtosecond low-energy electron sources. We report the nonlinear emission of ultrashort electron wave packets from a gold nanotip generated by nonlocal excitation and nanofocusing of surface plasmon polaritons. We verify the nanoscale localization of plasmon-induced electron emission by its electrostatic collimation characteristics. With a plasmon polariton pulse duration below 8 fs at the apex, we identify multiphoton photoemission as the underlying emission process. The quantum efficiency of the plasmon-induced emission exceeds that of photoemission from direct apex illumination. We demonstrate the application for plasmon-triggered point-projection imaging of an individual semiconductor nanowire at 3 µm tip-sample distance. Based on numerical simulations we estimate an electron pulse duration at the sample below 10 fs for tip-sample distances up to few micrometers. Plasmon-driven nanolocalized electron emission thus enables femtosecond point-projection microscopy with unprecedented temporal and spatial resolution, femtosecond low-energy electron in-line holography, and opens a new route towards femtosecond scanning tunneling microscopy and spectroscopy.

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Electron source brightness and degeneracy from Fresnel fringes in field emission point projection microscopy

Cited by 75 publications

References 0 publications

Temporal lenses for attosecond and femtosecond electron pulses

Temporal lenses for attosecond and femtosecond electron pulses

Ballistic Field Electron Emission from Demountable Single Atom Tip

Nanofocused Plasmon-Driven Sub-10 fs Electron Point Source

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