Advancing ultrafast (S)TEM with the combination of an RF cavity and an electrostatic beam blanker.

Abstract

Transmission electron microscopy (TEM) has significantly advanced fields such as materials science, nanotechnology, and structural biology by providing detailed structural and analytical information at picometer resolutions. To further enhance TEM's capabilities, time-resolved electron microscopy introduces the temporal domain, using ultrafast electron pulses to capture dynamic processes. Traditional methods generate these pulses via photocathode illumination by femtosecond lasers and face challenges like complex alignment and limited repetition rates. An alternative approach employing electronic devices as beam choppers, specifically resonant RF cavities in combination with electrostatic beam blankers, simplifies alignment and increases repetition rates, achieving picosecond and sub-picosecond pulses. Additionally, these devices do not compromise the performance of the microscope in any other imaging mode. The microscope can be rapidly toggled between continuous and pulsed imaging, providing flexibility of operation in modern research labs. This study integrates these beam choppers into high-end TEMs and demonstrates their effectiveness in achieving high temporal resolution for pump-probe experiments. Results show that these methods maintain high spatial resolution and coherence, making them a promising solution for ultrafast electron microscopy.