Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 84: Focus Session: Structural Dynamics in Nanoscale Materials Probed by Ultrashort Electron Pulses
O 84.4: Talk
Thursday, March 19, 2015, 16:00–16:15, MA 005
Coherence Properties of Laser-Triggered Field Emitters — •Dominik Ehberger1,2, Jakob Hammer1,2, Max Eisele2, Michael Krüger1,2, Jonathan Noe3, Alexander Högele3, and Peter Hommelhoff1,2,4 — 1Friedrich Alexander University Erlangen-Nuremberg, Department of Physics, D-91508 Erlangen — 2Max Planck Institute of Quantum Optics, D-85748 Garching — 3Fakultät für Physik and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, D-80539 München — 4Max Planck Institute for the Science of Light, D-91508 Erlangen
Sharp metal nanotips provide bright and spatially coherent electron beams in DC-field emission. They serve as workhorse in electron imaging and holography. However, the spatial coherence properties, commonly quantified by the effective source radius reff, are expected to depend strongly on the emission process and have so far not been measured for laser-triggered metal tips.
Here, we present a comparison of reff for a tungsten tip triggered with near-UV pulses and in DC-field emission. From electron interference patterns obtained by means of a freestanding carbon nanotube biprism an upper bound for reff is deduced. We find reff≤(0.80±0.05) nm in laser induced and reff≤(0.55±0.02) nm in DC-field emission, revealing that the spatial coherence is almost fully preserved in a one-photon emission process.
We expect this finding to have far-reaching ramifications for ultrafast electron imaging applications.