A coherent photofield electron source for fast diffractive and point-projection imaging

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Prospects for high-resolution imaging at femtosecond speeds using electron diffractive imaging are reviewed in the context of recent achievements using free-electron X-ray lasers. The conflict between Coulomb interactions and the spatial coherence of electron beams is identified as a limiting factor. Experimental results showing the performance of a milliwatt laser-driven fast photofield GaAs electron emitter are presented, including emission current and measured energy spread for various laser energies illuminating the electron emission tip. Band-bending below the Fermi level, due to penetration of the tip field into the emitter, is found to limit the emission energy spread by thermalizing the electrons. Because of the absence of beam crossovers and consequent Coulomb interactions, the point-projection photofield emission microscope with its high spatial coherence is suggested as a method for obtaining femtosecond images at high resolution from atomic processes, which may be triggered repetitively. The incorporation of a photofield emitter into a microwave pulse compression gun is discussed, as is the use of electron photofield emission from semiconductor donor states.

Original languageEnglish (US)
Pages (from-to)4691-4702
Number of pages12
JournalPhilosophical Magazine
Volume90
Issue number35-36
DOIs
StatePublished - Dec 14 2010

Fingerprint

electron sources
emitters
projection
electron emission
lasers
electrons
pulse compression
high resolution
illuminating
free electrons
energy
crossovers
penetration
microscopes
interactions
electron beams
microwaves
x rays

Keywords

  • fast imaging
  • femtosecond source
  • field emission
  • holography
  • laser
  • photofield emission

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

A coherent photofield electron source for fast diffractive and point-projection imaging. / Spence, John; Vecchione, T.; Weierstall, Uwe.

In: Philosophical Magazine, Vol. 90, No. 35-36, 14.12.2010, p. 4691-4702.

Research output: Contribution to journalArticle

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