Abstract
Creating, manipulating, and detecting coherent electrons is at the heart of future quantum microscopy and spectroscopy technologies. Leveraging and specifically altering the quantum features of an electron beam source at low temperatures can enhance its emission properties. Here, we describe electron field emission from a monocrystalline, superconducting niobium nanotip at a temperature of 5.9 K. The emitted electron energy spectrum reveals an ultranarrow distribution down to 16 meV due to tunable resonant tunneling field emission via localized band states at a nanoprotrusion’s apex and a cutoff at the sharp low-temperature Fermi edge. This is an order of magnitude lower than for conventional field emission electron sources. The self-focusing geometry of the tip leads to emission in an angle of 3.7°, a reduced brightness of , and a stability of hours at 4.1 nA beam current and 69 meV energy width. This source will decrease the impact of lens aberration and enable new modes in low-energy electron microscopy, electron energy loss spectroscopy, and high-resolution vibrational spectroscopy.
- Received 2 May 2022
- Accepted 29 September 2022
DOI:https://doi.org/10.1103/PhysRevLett.129.244802
© 2022 American Physical Society
Physics Subject Headings (PhySH)
Viewpoint
Enhanced Emission for Improved Electron Spectroscopy
Published 7 December 2022
Researchers have demonstrated a new electron field emitter with unprecedented brightness and spectral purity, promising a breakthrough in electron microscope spectroscopy.
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