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Ultrafast diffraction with single electrons
F. Kirchner, S. Lahme, M. Aidelsburger,
A. Gliserin, M. Walbran, C. Weninger,
F. Krausz, P. Baum
MPQ-LMU Laboratory for Attosecond & High-Field Physics
UESDM – December 13, 2012
Funding:
Rudolf-Kaiser-Foundation, European Research Council, Munich Center for Advanced Photonics
Single electron pulses
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Atoms and electrons in motion
Baum, Yang, Zewail,
Science 318, 788 (2007)
Movement of atoms/nuclei
Movement of electron density
femto- to picoseconds
attoseconds?
3
Examples of electron dynamics: iodine
Baum and Zewail, Chem. Phys. 366, 2 (2009)
for 100%
excitation 4
Experimental approach
• Ti:sapphire oscillator: 5 MHz, 500 nJ
• 0.1 to 10 electrons per pulse
• tunable rep.-rate down to 128 kHz
• water-cooled magn. lens in vacuum
• focus diameter on cathode: few microns
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Tailored excitation of metallic photocathodes
M. Aidelsburger, et al., PNAS, 107, 19714 (2010)
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Tailored excitation of metallic photocathodes
M. Aidelsburger, et al., PNAS, 107, 19714 (2010)
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Tailored excitation of metallic photocathodes
M. Aidelsburger, et al., PNAS, 107, 19714 (2010)
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Microwave cavity
A. Gliserin, et al, New Journal of Physics 14, 073055 (2012)
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Microwave cavity
A. Gliserin, et al, New Journal of Physics 14, 073055 (2012)
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Microwave generation / synchronization
Phase locked loop voltage-controlled oscillator (PLL-VCO)
F. Kiewiet, et al., Nucl. Instrum. Methods Phys. Res. A, 484, 619 (2002)
„Direct“ microwave extraction
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Characterization in the energy domain
• Wien filter
New Journal of Phys.
14, 073055 (2012)
• High-resolution ToF spectrometer
sub-1eV resolution at 30 keV
Drift tube design
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Temporal distortions in magnetic lenses
C. Weninger and P. Baum, Ultramicroscopy, 113, 145 (2012)
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‘Isochronic’ magnetic lenses
Simulation results
C. Weninger and P. Baum, Ultramicroscopy, 113, 145 (2012)
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Conclusion
Summary:
Drawbacks:
•
•
•
•
Single electron pulses
Tunable excitation of
photocathode
• Microwave compression
• ‘Isochronic’ magnetic lenses
• High spatial coherence
Reversible processes
Sample relaxation/damage at
high repetition rates
Perspective:
•
•
Study atomic motions in solid state samples
Expand electron diffraction to study electron density in motion
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