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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
2
Single electron
pulses
3
Atoms and electrons
in motion
Baum, Yang, Zewail, Science 318, 788 (2007)
Movement
of atoms/nuclei
femto-
to picoseconds
Movement
of electron
density
attoseconds?
4
Examples
of electron
dynamics: iodine
Baum and Zewail, Chem. Phys. 366, 2 (2009)for 100%excitation
5
Experimental approach
• Ti:sapphire
oscillator: 5 MHz, 500 nJ
• tunable rep.-rate down to 128 kHz
• focus diameter on cathode: few microns
• 0.1 to 10 electrons per pulse
• water-cooled magn. lens in vacuum
6
Tailored excitation of metallic photocathodes
M. Aidelsburger, et al., PNAS, 107, 19714 (2010)
7
Tailored excitation of metallic photocathodes
M. Aidelsburger, et al., PNAS, 107, 19714 (2010)
8
Tailored excitation of metallic photocathodes
M. Aidelsburger, et al., PNAS, 107, 19714 (2010)
9
Microwave cavity
A. Gliserin, et al, New Journal of Physics 14, 073055 (2012)
10
Microwave cavity
A. Gliserin, et al, New Journal of Physics 14, 073055 (2012)
11
Microwave
generation
/ synchronization
F. Kiewiet, et al., Nucl. Instrum. Methods Phys. Res. A, 484, 619 (2002)
Phase locked
loop
voltage-controlled
oscillator
(PLL-VCO)
„Direct“
microwave
extraction
12
Characterization in the energy domain
• Wien
filter
New Journal of Phys. 14, 073055 (2012)
• High-resolution ToF
spectrometersub-1eV resolution
at 30 keV
Drift tube design
13
Temporal distortions
in magnetic
lenses
C. Weninger and P. Baum, Ultramicroscopy, 113, 145 (2012)
14
‘Isochronic’
magnetic lenses
Simulation results
C. Weninger and P. Baum, Ultramicroscopy, 113, 145 (2012)
17
Conclusion
Summary:
•
Single electron pulses•
Tunable excitation of photocathode
•
Microwave compression•
‘Isochronic’ magnetic lenses•
High spatial coherence
Drawbacks:
•
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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