High-coherence picosecond electron bunches from cold atoms

Area of Science:

• Physics
• Chemistry
• Materials Science

Background:

• Ultrafast electron diffraction (UED) offers atomic resolution for molecular dynamics.
• Current UED is limited by low transverse coherence in electron sources.
• Laser-cooled atom photoionization provides high coherence but is too slow for UED.

Purpose of the Study:

• To overcome limitations in UED by developing a novel electron source.
• To achieve high transverse coherence and picosecond pulse durations for UED.
• To enable single-shot electron diffraction from biological samples.

Main Methods:

• A two-color laser excitation process was employed.
• Femtosecond laser excitation was followed by nanosecond photoionization.
• Laser-cooled atoms were used as the electron source.

Main Results:

• Picosecond electron bunches with high transverse coherence were successfully generated.
• The method overcomes the expected loss of coherence from short laser pulses.
• Demonstrated potential for 3D bunch shaping of electron sources.

Conclusions:

• The developed method advances UED capabilities for studying ultrafast molecular dynamics.
• This technique holds promise for single-shot electron diffraction of crystalline biological samples.
• Offers a pathway to meet brightness and coherence requirements for advanced UED applications.