High spatial coherence in multiphoton-photoemitted electron beams

Abstract

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 $(0.65\pm 0.06)$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.

5 pages, 3 figures

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• Ultrafast time resolved photo-electric emission

Cited by in corpus (6)

• Light emission is fundamentally tied to the quantum coherence of the emitting particle
• Femtosecond laser-induced electron emission from nanodiamond-coated tungsten needle tips
• Quantum Nanophotonics with Energetic Particles:X-rays and Free Electrons
• Quantum wavefunction reconstruction by free-electron spectral shearing interferometry
• Hanbury Brown and Twiss interference of electrons in free space from independent needle tip sources
• Coulomb interactions and the spatial coherence of femtosecond nanometric electron pulses