Coherent X-ray scattering from soft-matter surfaces
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Date
2007-01-11T12:53:11Z
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Abstract
The main focus of the thesis is the special application of X-ray
photon correlation spectroscopy (XPCS) to the study of surface
dynamics. Since XPCS is still a very new technique, not all effects
and measurement artifacts are commonly taken into account during data
analysis. The finite coherence of the radiation and other effects
yield a limited experimental resolution, which modifies the results
significantly, i.e. the measured dynamic structure factor of the
sample is broadened and shifted. XPCS resolution effects are studied
experimentally and the implementation of a simplified convolution
formalism is tested, which makes it possible to take resolution
effects into consideration in a practical way.
A possible slight dependence of the experimental resolution (i.e. the
coherence of the X-rays) on the sample material has been observed
during the XPCS experiments. To get more information on this effect,
Young's double-slit experiment is combined with a surface-sensitive
scattering setup to analyse the coherence properties of the specularly
scattered radiation. The results indicate a sample-dependent decrease
in the coherence of the scattered radiation.
Furthermore, measurements on thin adsorbed alkane films on silicon
substrates are discussed. The results indicate that the sample is
static on the observed length scales, resulting in static speckle
patterns during the measurements.
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Keywords
Röntgenstrahlung, Kohärenz, Oberflächendynamik, Auflösung, X-rays, Coherence, XPCS, Surface dynamics, Resolution