Ultrashort pulse electron gun with a MHz repetition rate

Wytrykus, D.; Centurion, Martin; Reckenthaeler, Peter; Krausz, Ferenc; Apolonski, Alexander; Fill, Ernst E.

doi:10.1007/s00340-008-3355-1

Cited by 7 publications

(9 citation statements)

References 16 publications

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“…This marks a significant improvement over conventional sources of electron pulses, where temporal broadening was reported in the 150-to 300-fs regime (14,18,29,33). In spite of the lower quantum efficiency at 286 nm, single or a few electrons per pulse can still be generated with our optical UV source.…”

Section: Resultsmentioning

confidence: 85%

“…The transverse velocity spread of photoelectrons can be determined by measurements of the electron beam diameter (29). The trajectory of an electron with a transverse velocity v t (see Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Femtosecond pulses at fixed wavelengths of 266, 400, and 800 nm were recently used on metals to study the differences between single-and multiphoton excitation (29). Here, we report an investigation of photoelectric emission with tunable femtosecond pulses from well above to below the work function.…”

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confidence: 99%

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Single-electron pulses for ultrafast diffraction

Aidelsburger

Kirchner

Krausz

et al. 2010

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

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154

161

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Visualization of atomic-scale structural motion by ultrafast electron diffraction and microscopy requires electron packets of shortest duration and highest coherence. We report on the generation and application of single-electron pulses for this purpose. Photoelectric emission from metal surfaces is studied with tunable ultraviolet pulses in the femtosecond regime. The bandwidth, efficiency, coherence, and electron pulse duration are investigated in dependence on excitation wavelength, intensity, and laser bandwidth. At photon energies close to the cathode's work function, the electron pulse duration shortens significantly and approaches a threshold that is determined by interplay of the optical pulse width and the acceleration field. An optimized choice of laser wavelength and bandwidth results in sub-100-fs electron pulses. We demonstrate single-electron diffraction from polycrystalline diamond films and reveal the favorable influences of matched photon energies on the coherence volume of single-electron wave packets. We discuss the consequences of our findings for the physics of the photoelectric effect and for applications of singleelectron pulses in ultrafast 4D imaging of structural dynamics.I nvestigation of structural dynamics in condensed matter and molecules by four-dimensional imaging calls for resolution of Angstrom-scale distances with femtosecond timing. These resolutions are provided by ultrafast electron diffraction and microscopy techniques, which are based on pump-probe arrangements with a femtosecond laser for excitation and with ultrashort electron packets for measuring sequences of atomic-scale structures during changes (1). Recently reported studies include such of reaction pathways during phase transformations (2), chemical reactions (3), laser ablation (4), molecular alignment (5), changes at interfaces (6), heating and melting processes (7-9), cantilever motion (10), or evanescent fields around nanostructures (11), among many others (12). Possibilities to access the attosecond regime of charge density motion are also discussed (13), taking into account the generation of pulses (14-16) and the quantum dynamics of the scattering process (17).These (and many more) achievements are made possible by the use of ultrashort electron packets at multi-kiloelectron-volt energies for time-resolved diffraction and imaging. Such packets can be generated by photoelectric emission from metal films illuminated with femtosecond lasers, followed by acceleration in static or radio-frequency electric fields. In multielectron packets, space-charge effects dominate the temporal structure and energy distribution; hence electron density has to be traded off against resolution (18,19). In contrast, space charge is absent in packets containing only one single electron at a time (12). In this regime, the longitudinal and transverse emittance, and hence the pulse duration, bandwidth, and coherence, are determined by the spatiotemporal statistics of the photoelectric effect.Some theoretical models consider the femtos...

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Section: Resultsmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Single-electron pulses for ultrafast diffraction

Aidelsburger

Kirchner

Krausz

et al. 2010

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

Self Cite

154

161

View full text Add to dashboard Cite

show abstract

“…These practical difficulties with conventional photoemission sources motivated the present research and application of a two-photon process for electron emission. Such an approach was briefly mentioned earlier [2,27,41,42], but neither details were given nor were tunable pulses applied. The expected advantage of twophoton photoemission is a second-order scaling between electron generation efficiency and the optical peak intensity at the photocathode material.…”

Section: Two-photon Photoemissionmentioning

confidence: 99%

Femtosecond single-electron pulses generated by two-photon photoemission close to the work function

et al. 2015

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Diffraction and microscopy with ultrashort electron pulses can reveal atomic-scale motion during matter transformations. However, the spatiotemporal resolution is significantly limited by the achievable quality of the electron source. Here we report on the emission of femtosecond single/fewelectron pulses from a flat metal surface via two-photon photoemission at 50-100 kHz. As pump we use wavelength-tunable visible 40 fs pulses from a noncollinear optical parametric amplifier pumped by a picosecond thin-disk laser. We demonstrate the beneficial influence of photon energies close to the photocathode's work function for the coherence and duration of the electron pulses. The source's stability approaches the shot noise limit after removing second-order correlation with the driving laser power. Two-photon photoemission offers genuine advantages in minimizing emission duration and effective source size directly at the location of photoemission. It produces an unprecedented combination of coherent, ultrashort and ultrastable single/few-electron wave packets for timeresolving structural dynamics.

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“…The laser pulses at the cathode had a duration of τ laser ≈ 70 ± 20 fs; this is the duration of the 266 nm pulses after a dispersive vacuum window. τ disp is determined by the photoemission bandwidth and the acceleration gradient [4,17,20,33]. In our experiments, the photocathode was excited at a wavelength of 266 nm, corresponding to photon energies of 4.65 eV.…”

Section: Estimation Of Jittermentioning

confidence: 99%

Compression of single-electron pulses with a microwave cavity

Gliserin¹,

Apolonski²,

Krausz³

et al. 2012

New J. Phys.

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Few-femtosecond to attosecond electron pulses are required for advancing ultrafast diffraction and microscopy to the regime of electrons in motion. Here, we report the combination of a single-electron source with a microwave cavity for pulse compression. In such an arrangement, the electron pulses can become significantly shorter than the laser pulses used for electron generation. This comes at the expense of an increase in energy spread. We report the use of an energy analyzer for characterizing microwave-compressed singleelectron pulses. Phase effects, linearity, focal distances, incoming pulse durations and laser-microwave jitter are measured for three different synchronization approaches. The results demonstrate the applicability of a microwave cavity in the single-electron regime and identify jitter as the current limitation on the way to few-femtosecond, eventually attosecond pulses of single electrons.

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Ultrashort pulse electron gun with a MHz repetition rate

Cited by 7 publications

References 16 publications

Single-electron pulses for ultrafast diffraction

Single-electron pulses for ultrafast diffraction

Femtosecond single-electron pulses generated by two-photon photoemission close to the work function

Compression of single-electron pulses with a microwave cavity

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