Erlangen 2022 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 18: Laser and Laser Applications
Q 18.5: Talk
Tuesday, March 15, 2022, 11:30–11:45, Q-H15
Highly localized field enhancement at sputter-sharpened tungsten nanotips — •Leon Brückner1, Timo Paschen1,2, Mingjian Wu3, Erdmann Spiecker3, and Peter Hommelhoff1 — 1Department Physik, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), 91058 Erlangen — 2Korrelative Mikroskopie und Materialdaten, Fraunhofer-Institut für Keramische Technologien und Systeme IKTS, 91301 Forchheim — 3Department Werkstoffwissenschaften, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), 91058 Erlangen
Nanotips, i.e., ultrasharp, nanometer-scale protrusions on the surface of field emitter needle tips, are known to have intriguing properties, such as highly localized field enhancement and electron emission, and a narrow transverse energy distribution through emission from surface states. We fabricated nanotips from regular tungsten needle tips via an in-situ ion sputtering technique and investigated their geometry through transmission electron microscope imaging. The field enhancement at the nanotip is probed via laser-driven electron rescattering. Extracting the near-field enhancement factor from the electron energy spectra yields an increase of more than a factor of 2 compared to a regular needle tip, i.e., 8.2 ± 0.2 as compared to 4-5. The experimental results are well reproduced by finite-difference time-domain simulations and bode well for potential applications in strong-field physics or as electron sources for ultrafast electron microscopy.