Tunable electron beam pulser for picoseconds stroboscopic microscopy in transmission electron microscopes

Area of Science:

• Materials Science
• Physics
• Electron Microscopy

Background:

• Time-resolved transmission electron microscopy (TEM) traditionally uses pulsed lasers for electron bunch generation.
• Laser-based systems are complex and not always user-friendly, limiting accessibility for studying ultrafast dynamics.

Purpose of the Study:

• To retrofit a commercial TEM for tunable pulsed electron beam generation without an external laser.
• To enable high-repetition-rate stroboscopic experiments and explore new temporal regimes in materials analysis.

Main Methods:

• Integration of RF-driven traveling wave stripline elements and quadrupole magnets into a 200 keV TEM.
• Development of a system for continuously tunable pulsed electron beams with adjustable repetition rates (0.1-12 GHz) and bunch lengths (10 ps - 10 ns).
• Implementation of three operational modes: continuous waveform (CW), stroboscopic (pump-probe), and pulsed beam modes.

Main Results:

• Successful retrofit of a commercial TEM, enabling tunable pulsed electron beam generation without lasers.
• Demonstrated operation across a wide range of repetition rates and bunch lengths.
• Evaluated image quality using Au nanoparticles, showing the potential for observing ultrafast reversible dynamics.

Conclusions:

• The laser-free add-on beam pulser significantly enhances TEM capabilities for studying ultrafast material dynamics.
• This innovation provides access to high-repetition-rate stroboscopic experiments previously unattainable.
• The system offers versatile operation modes suitable for various research needs, including dose-rate sensitive materials.