Westfälische Wilhelms-Universität Münster
- Fachbereich Physik -
ALLGEMEINES PHYSIKALISCHES KOLLOQUIUM
Mittwoch, 21. Januar 1998
Prof. Dr. P. Kruit
Delft University of Technology
New Directions in Very High Resolution
Analytical Electron Microscopy
Sub nanometer resolution analytical microscopy can be advanced by innovations
in three different areas. First of all, it is still possible to improve
the spatial resolution of existing methods, either by traditional means
such as smaller aberrations and disturbances or by revolutionary means
such as aberration correction or standing wave illumination. At these levels
of resolution it is important to pay as much attention to the microscope
alignment and the electronwave-specimen interaction as in high resolution
transmission electron microscopy. Then, existing methods of microanalysis
can be developed further, either by increasing the detection efficiency
or by enhancing the spectral resolution. Electron energy loss Spectroscopy
(EELS) seems to fit best with very high spatial resolution, but much can
be gained in terms of energy resolution. It is time to decrease the energy
spread of the primary beam such that an EELS resolution of about 50-100
meV can be obtained for high resolution chemical shift measurements. Finally,
as the third area of innovation, new information channels can be explored.
A start has been made on adding Auger spectroscopy and Auger-EELS coincidence
spectroscopy to the STEM, but much work still has to be performed before
that can be as standard as X-ray analysis or EELS. Real innovations can
come from new methods such as electron stimulated desorption. The presentation
will concentrate on a discussion of necessary instrumental developments
for examples in all three areas: standing wave illumination, monochromatization
of the primary beam and efficient detection of coincidence spectra.
Ort: Wilhelm-Klemm-Str. 9, Hörsaal 404
Zeit: 17 Uhr c.t.
Einladender: Kohl