Femtosecond Time-resolved MeV Electron Diffraction

TL;DR

This paper demonstrates femtosecond electron diffraction using high-brightness MeV electron beams, achieving high-quality, single-shot diffraction patterns with temporal resolution of 130 fs, highlighting advantages like longer coherence and potential for 10 fs resolution.

Contribution

The study experimentally demonstrates femtosecond electron diffraction with MeV electrons, achieving high-quality patterns and 130 fs temporal resolution, advancing the capabilities of ultrafast electron diffraction techniques.

Findings

Achieved single-shot diffraction patterns for aluminum and 1T-TaS2.

Demonstrated 130 fs temporal resolution in observing material dynamics.

Confirmed electron beam emittance of ~50 nm-rad and coherence lengths of ~11 nm and ~2.5 nm.

Abstract

We report the experimental demonstration of femtosecond electron diffraction using high-brightness MeV electron beams. High-quality, single-shot electron diffraction patterns for both polycrystalline aluminum and single-crystal 1T-TaS2 are obtained utilizing a 5 femto-Coulomb (~3x10^4 electrons) pulse of electrons at 2.8 MeV. The high quality of the electron diffraction patterns confirm that electron beam has a normalized emittance of ~50 nm-rad. The corresponding transverse and longitudinal coherence length are ~11 nm and ~2.5 nm, respectively. The timing jitter between the pump laser and probe electron beam was found to be ~ 100 fs (rms). The temporal resolution is demonstrated by observing the evolution of Bragg and superlattice peaks of 1T-TaS2 following an 800 nm optical pump and was found to be 130 fs. Our results demonstrate the advantages of MeV electron diffraction: such as longer coherent lengths, large scattering cross-section and larger signal-to-noise ratio, and the feasibility of ultimately realizing 10 fs time-resolved electron diffraction.