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  • Open Access

Energy offset between femtosecond and thermal electrons in nanometer field-emitter tips

Daniel Kazenwadel, Jacob Holder, Joel Kuttruff, and Peter Baum*

  • *Contact author: peter.baum@uni-konstanz.de
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Phys. Rev. Applied 24, 024021 – Published 8 August, 2025

DOI: https://doi.org/10.1103/y8mq-nhx2

Abstract

We investigate the ultrafast photoelectric effect at sharp tungsten needles and find a considerable energy offset between thermally emitted and photoemitted electrons. Neither changes in temperature nor tuning the work function by the Schottky effect strongly affect the free-space energy of the photoelectrons. We explain these discoveries by a direct optical excitation within the band structure of tungsten, followed by scatter-free transport to the surface and emission into free space. Experiments at different photon energies support that the material and not the photon energy determines the primary properties of the electron beam.

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Phys. Rev. Applied 24, 024021– Published 8 August, 2025
  • Received 1 January 2025
  • Revised 3 July 2025
  • Accepted 15 July 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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