Femtosecond electrons probing currents and atomic structure in nanomaterials

TL;DR

This paper introduces a hybrid femtosecond electron microscopy technique combining point projection microscopy and low-energy electron diffraction to study ultrafast currents and structural dynamics in nanomaterials with high temporal and spatial resolution.

Contribution

It presents a novel approach using laser-triggered electron sources for femtosecond imaging of electronic and structural dynamics in low-dimensional nanomaterials.

Findings

Achieved sub-100 femtosecond temporal resolution.

Demonstrated imaging of ultrafast electric currents in nanowires.

Showcased potential for studying structural dynamics in 2D materials.

Abstract

The investigation of ultrafast electronic and structural dynamics in low-dimensional systems like nanowires and two-dimensional materials requires femtosecond probes providing high spatial resolution and strong interaction with small volume samples. Low-energy electrons exhibit large scattering cross sections and high sensitivity to electric fields, but their pronounced dispersion during propagation in vacuum so far prevented their use as femtosecond probe pulses in time-resolved experiments. Employing a laser-triggered point-like source of either divergent or collimated electron wave packets, we developed a hybrid approach for femtosecond point projection microscopy and femtosecond low-energy electron diffraction. We investigate ultrafast electric currents in nanowires with sub-100 femtosecond temporal and few 10 nm spatial resolutions and demonstrate the potential of our approach for studying structural dynamics in crystalline single-layer materials.