Non-invasive time-sorting in radio-frequency compressed ultrafast electron diffraction

TL;DR

This paper introduces a non-invasive, energy-based time-sorting method for ultrafast electron diffraction that significantly improves temporal resolution by correcting timing jitter through beam energy measurements, applicable to various UED setups.

Contribution

The authors present a novel energy-based time-sorting technique for UED that enhances temporal resolution without requiring major infrastructure changes.

Findings

Achieved 35 fs rms timing correction in 3 MeV electron beams.

Method applicable to both keV and MeV UED systems.

Extended UED temporal resolution beyond 100 fs jitter limit.

Abstract

We demonstrate a non-invasive time-sorting method for ultrafast electron diffraction (UED) experiments with radio-frequency (rf) compressed electron beams. We show that electron beam energy and arrival time at the sample after rf compression are strongly correlated such that the arrival time jitter may be corrected through measurement of the beam energy. The method requires minimal change to the infrastructure of most of the UED machines and is applicable to both keV and MeV UED. In our experiment with ~3 MeV beam, the timing jitter after rf compression is corrected with 35 fs root-mean-square (rms) accuracy, limited by the 3x10^-4 energy stability. For keV UED with high energy stability, sub-10 fs accuracy in time-sorting should be readily achievable. This time-sorting technique allows us to retrieve the 2.5 THz oscillation related to coherent A1g phonon in laser excited Bismuth film and extends the temporal resolution of UED to a regime far beyond the 100-200 fs rms jitter limitation.