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A kiloelectron-volt ultrafast electron micro-diffraction apparatus using low emittance semiconductor photocathodes
W H Li1, C J R Duncan1, M B Andorf1
1Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853, USA.
Structural Dynamics (Melville, N.Y.)
|March 30, 2022
Summary
Researchers developed a new time-resolved electron diffraction system for ultrafast studies. This advanced apparatus achieves high brightness electron bunches with exceptional spatial and temporal resolution for materials science research.
Area of Science:
- Materials Science
- Physics
- Chemistry
Background:
- Ultrafast electron diffraction (UED) is crucial for studying dynamic processes in materials.
- Existing UED systems face limitations in probe size, coherence, and time resolution.
- High brightness electron sources are essential for advancing UED capabilities.
Purpose of the Study:
- To design and demonstrate a novel time-resolved electron diffraction apparatus.
- To achieve simultaneous single-digit micrometer probe size, long coherence length, and 200 fs root-mean-square time resolution.
- To enable high-brightness electron bunch generation for advanced UED experiments.
Main Methods:
- Utilized high efficiency, low emittance semiconductor photocathodes.
- Employed a wavelength near the photoemission threshold for electron generation.
- Operated the system at a repetition rate up to 250 kHz.
- Characterized spatial, temporal, and reciprocal space resolution.
Main Results:
- Achieved intense electron bunches with single-digit micrometer probe size.
- Demonstrated 200 fs root-mean-square time resolution and long coherence length.
- Measured peak beam brightness of in micro-diffraction mode.
- Successfully performed proof-of-principle measurements of ultrafast heating in gold.
Conclusions:
- The developed apparatus offers significant improvements in UED capabilities.
- The system enables detailed investigation of ultrafast phenomena in materials.
- Experimental results align with simulations, validating the apparatus performance.
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