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

TL;DR

This paper introduces a novel ultrafast transmission electron microscope driven by a laser-induced field emitter, achieving femtosecond temporal resolution and high coherence, enabling advanced ultrafast imaging and spectroscopy.

Contribution

It presents the first UTEM based on localized photoemission from a Schottky emitter, with tunable pulse structure and record beam properties for ultrafast electron microscopy.

Findings

Achieved 200 fs pulse duration and 9 Å focused beam diameter.

Demonstrated capabilities for ultrafast imaging, diffraction, holography, and spectroscopy.

Enabled exploration of quantum coherent interactions with free electron beams.

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 G\"ottingen 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 {\AA} 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.