Towards the Limits of Holography with Low Energy Electrons
The use of a coherent single-atom electron source for low energy electrons
has developed into a tool that appears to be particular useful for investigating
individual objects of nanometer-sized dimensions. The absence of radiation
damage due to the low energy of the electrons and the high contrast in scattering
off light atoms holds promise for a new tool for structural biology of individual
molecules. The sensitivity to small electric and magnetic fields, combined
with the high spatial and time resolution of the technique, shall also be
used to explore the properties of mesoscopic physics objects, like quantum
wires and single electron devices. This project aims at reaching the experimental
resolution limit of this technique to then be made available to other projects,
both inside as well as outside of our research group. The ultimate limit is
given by the spatial and temporal coherence of the source. It relates to the
size of the source and the energy spread of the emitted electrons, fundamentally
limited only by the Heisenberg uncertainty relationship. In order to come
close to this fundamental limit, associated with atomic resolution in 3 dimensions,
a number of experimental issues need to be addressed and new technologies
developed. They include: shielding the coherent electron source from external
mechanical and electronic noise, developing a new 2-dimensional detector for
low energy electrons and improving the angular spread of the coherent electron
wave-fronts by adsorbing C60 clusters onto the atomic point-source.The numerical
work of Tatiana Latychevskaia is directed towards the important second step
in holography, namely the reconstruction. This implies employing appropriate
coherent optics schemes for reconstructing the 3-dimensional structure of
the nanometer-sized object from its experimental electron hologram record.
Contacts: Tatiana Latychevskaia, Conrad Escher, Hans-Werner Fink
The work is supported by the EU Project SIBMAR
Further reading:
Solution of the Twin Image Problem in Holography, Tatiana Latychevskaia and Hans-Werner Fink, Preprint (2006) (PDF-File)
Towards on-line Reconstruction of Electron Holograms Tatiana Latychevskaia, Hans-Werner Fink, Poster for NCCR site visit Basel, May 2003, (PDF file: 3.25 MB)
Holography with Low Energy Electrons,
Principles and Applications H.-W. Fink, Springer Verlag (1998)