Ultrafast transmission electron microscopy using a laser-driven field emitter: Femtosecond resolution with a high coherence electron beam

TLDR

The Göttingen UTEM introduces a new ultrafast TEM source based on nano‑localized linear photoemission from a Schottky emitter, allowing freely tunable temporal structure from continuous wave to femtosecond pulsed mode. The study aims to develop the first ultrafast transmission electron microscope driven by localized photoemission from a field‑emitter cathode. The authors implement a nano‑localized Schottky photoemitter that delivers tunable temporal structure and quantify beam parameters including pulse duration, energy width, and beam diameter. The UTEM achieves record pulse properties—9 Å focused beam diameter, 200 fs pulse duration, and 0.6 eV energy width—and enables ultrafast imaging, diffraction, holography, spectroscopy, and potential quantum coherent interactions with intense laser fields.

Abstract

We present the development of the first ultrafast transmission electron microscope (UTEM) driven by localized photoemission from a field emitter cathode. We describe the implementation of the instrument, the photoemitter concept and the quantitative electron beam parameters achieved. Establishing a new source for ultrafast TEM, the Göttingen UTEM employs nano-localized linear photoemission from a Schottky emitter, which enables operation with freely tunable temporal structure, from continuous wave to femtosecond pulsed mode. Using this emission mechanism, we achieve record pulse properties in ultrafast electron microscopy of 9 Å focused beam diameter, 200 fs pulse duration and 0.6 eV energy width. We illustrate the possibility to conduct ultrafast imaging, diffraction, holography and spectroscopy with this instrument and also discuss opportunities to harness quantum coherent interactions between intense laser fields and free-electron beams.