GHz laser-free time-resolved transmission electron microscopy: A stroboscopic high-duty-cycle method

Area of Science:

• Physics
• Materials Science
• Electron Microscopy

Background:

• Time-resolved transmission electron microscopy (TEM) often relies on laser systems for sample excitation and electron beam probing.
• Existing methods can induce sample heating or damage, limiting experimental possibilities.
• A need exists for laser-free, high-repetition-rate electron pulse generation for advanced TEM applications.

Purpose of the Study:

• To present a novel device and method for producing ultrashort electron pulses with GHz repetition rates.
• To demonstrate the application of this technology in creating a GHz stroboscopic TEM.
• To enable new in situ and in operando studies of materials driven by external electromagnetic fields.

Main Methods:

• Development of an electromagnetic-mechanical pulser (EMMP) using transverse deflecting cavities and magnetic quadrupoles.
• Modulation and chopping of a direct current (dc) electron beam to generate pico- and sub-pico-second pulses.
• Utilizing radiofrequency (RF) sources for synchronized external driving of the EMMP and sample, eliminating the need for lasers.

Main Results:

• Achieved ultrashort electron pulse sequences with repetition rates exceeding 1 GHz.
• Demonstrated negligible degradation of electron pulse phase-space.
• Developed a continuously tunable temporal pulse length and repetition rate.
• Realized a GHz stroboscopic TEM without laser components, preventing laser-induced sample damage.

Conclusions:

• The EMMP offers a robust, laser-free method for generating high-repetition-rate ultrashort electron pulses.
• This technology facilitates GHz stroboscopic TEM, opening new avenues for in situ and in operando material analysis.
• Applications span energy, electronics, and advanced functional materials, enabling the study of charge transport and dynamic phenomena.