X-RAY IMAGING OF POLYCRYSTALLINE AND AMORPHOUS
MATERIALS
T. Wroblewski, HASYLAB at DESY, Notkestr. 85,
D-22603 Hamburg
A novel method for obtaining position resolved
information
simultaneously from an entire plane of a
polycrystalline or amorphous
sample using the diffracted radiation or
fluorescence has been
developed. It makes use of a microchannelplate
as a collimator in front
of a position sensitive detector (CCD-camera).
The resolution thus
obtained is 30 µm with a field of view of
12*12 mm².
Experiments may be performed either in
transmission or in reflection
geometry. In the first case a 'flat' parallel
beam illuminates a slice
through the sample while in the second case the
surface of the specimen
is illuminated by a broad beam.
Typical fields of application are:
- non-destructive investigations of
the distribution of polycrystalline components
in composites
- reciprocal space mapping to determine the
mutual influence of
strain and orientation in adjacent grains in a
polycrystalline material
- analysis of the distribution of chemical
elements or even valence
states (using the chemical shift of the
absorption edges) via their
fluorescence
The use monochromatized synchrotron radiation is
recommended for two
reasons: the diffraction experiments require
high
collimation, and for the selective excitation of
fluorescence a
source with tunable energy is needed.