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High-purity free-electron momentum states prepared by three-dimensional optical phase modulation
No full textHigh-purity free-electron momentum states prepared by three-dimensional optical phase modulation
No full textTheory of electron energy loss near plasmonic wires, nanorods, and cones
No full textWe present an analytical description of the electron energy loss near plasmonic nanostructures with cylindrical symmetry as a three-step process: (i) electron-induced excitation of surface plasmon modes, (ii) their propagation and reflection, and (iii) the backaction on the electrons. The model incorporates relativistic effects, retardation, and light emission, and can treat arbitrary tilted electron trajectories. Convincing agreement with recent experimental data is demonstrated
Strong-field photoemission from surfaces: Theoretical approaches
No full textThe problem of highly nonlinear photoemission from a metal surface is considered using analytical and numerical approaches. Descriptions are found which cover both the weak-field and the strong-field regimes and the transition between them. The results of a time-dependent perturbation theory are in very good agreement with those from more numerically involved schemes, including a variational version of the Floquet method and a Crank-Nicolson-like numerical scheme. The implemented Crank-Nicolson variant uses transparent boundary conditions and an incident plane-wave state in the metal. Both numerical approaches give very similar results for weak and intermediate fields, while in the strong-field regime the Crank-Nicolson scheme is more effective than the Floquet method. We find an enhancement in the effective nonlinearity in the weak-field regime, which is caused by surface scattering of the final state. The presented theory also covers angular emission probabilities as a function of light intensity and explains an increase toward forward emission with growing field strength
Tailored high-contrast attosecond electron pulses for coherent excitation and scattering
Full text linkTemporally shaping the density of electron beams using light forms the basis for a wide range of established and emerging technologies, including free-electron lasers and attosecond electron microscopy. The modulation depth of compressed electron pulses is a key figure of merit limiting applications. In this work, we present an approach for generating background-free attosecond electron pulse trains by sequential inelastic electron-light scattering. Harnessing quantum interference in the fractional Talbot effect, we suppress unwanted background density in electron compression by several orders of magnitude. Our results will greatly enhance applications of coherent electron-light scattering, such as stimulated cathodoluminescence and streaking
High-purity free-electron momentum states prepared by three-dimensional optical phase modulation
No full text
Strong-field photoemission in nanotip near-fields: from quiver to sub-cycle electron dynamics
No full textMetallic nanotips exhibit large electric field enhancements over an extremely broad bandwidth spanning from the optical domain down to static fields. They therefore constitute ideal model systems for the investigation of the inherent frequency scalings of highly nonlinear and strong-field phenomena. Here, we present a comprehensive study of strong-field photoemission from individual metallic nanotips. Combining high local fields and variable-wavelength mid-infrared pulses, we investigate electron dynamics governed by the nanoscale confinement of the optical near-field. In particular, we characterize a transition to sub-cycle, field-driven electron acceleration. The experimental findings are corroborated by semiclassical calculations within a two-step model.Deutsche Forschungsgemeinschaft [SPP 1391, SFB 1073
High-purity free-electron momentum states prepared by three-dimensional optical phase modulation
Full text linkWe demonstrate the quantized transfer of photon energy and transverse momentum to a high-coherence electron beam. In an ultrafast transmission electron microscope, a three-dimensional phase modulation of the electron wave function is induced by transmitting the beam through a laser-illuminated thin graphite sheet. This all-optical free-electron phase space control results in high-purity superpositions of linear momentum states, providing an elementary component for optically programmable electron phase plates and beam splitters
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