A Compact Ultrafast Electron Diffractometer with Relativistic Femtosecond Electron Pulses

Jinfeng Yang,Yoichi Yoshida,Shouichi Sakakihara,Kazuki Gen,Nobuyasu Naruse

doi:10.3390/qubs4010004

Abstract

We have developed a compact relativistic femtosecond electron diffractometer with a radio-frequency photocathode electron gun and an electron lens system. The electron gun generated 2.5-MeV-energy electron pulses with a duration of 55 ± 5 fs containing 6.3 × 104 electrons per pulse. Using these pulses, we successfully detected high-contrast electron diffraction images of single crystalline, polycrystalline, and amorphous materials. An excellent spatial resolution of diffraction images was obtained as 0.027 ± 0.001 Å−1. In the time-resolved electron diffraction measurement, a laser-excited ultrafast electronically driven phase transition in single-crystalline silicon was observed with a temporal resolution of 100 fs. The results demonstrate the advantages of the compact relativistic femtosecond electron diffractometer, including access to high-order Bragg reflections, single shot imaging with the relativistic femtosecond electron pulse, and the feasibility of time-resolved electron diffraction to study ultrafast structural dynamics.

Highlights

Ultrafast electron diffraction (UED) with femtosecond temporal resolution is a powerful tool to observe directly dynamic processes in materials science, chemistry, and biology
We present the demonstrations on the electron diffractions of single crystalline, polycrystalline, and amorphous materials, and the time-resolved UED measurement of single crystalline silicon using relativistic femtosecond electron pulses
The single crystalline Si sample was produced from a tracer (GPT) code [27] at the rf gun launch phase of 30° with the 266-nm and 54-fs laser illumination

Summary

Introduction

Ultrafast electron diffraction (UED) with femtosecond temporal resolution is a powerful tool to observe directly dynamic processes in materials science, chemistry, and biology. We present the demonstrations on the electron diffractions of single crystalline, polycrystalline, and amorphous materials, and the time-resolved UED measurement of single crystalline silicon using relativistic femtosecond electron pulses.

Results

Conclusion