Chemistry Reference
In-Depth Information
FIGURE 10.3 Two-dimensional SAXS system (Bruker AXS NanoSTAR): (a) side view;
(b) top view showing complete beam path.
MikroGap V
˚
NTEC-2000 detector in a WAXS configuration. The primary beam
stop is made of material with high absorption and low fluorescence, such as gold,
tantalum, tungsten, or Pb-Sb alloy. The size of the beam stop is selected on the
basis of the beam size and divergence. It is held in place by two Kapton strings in a 90
cross and its position can be adjusted by micrometers through the vacuum
feedthroughs.
10.2.3 Detector Correction and System Calibration
The 2D detector should be corrected for nonuniform efficiency (flood field) and
geometric distortion (spatial). The detailed description on flood field and spatial
correction is given in Chapter 6. For a SAXS system, since the detector cannot be
driven away from the primary beam, amorphous fluorescence materials, such as
glassy iron foil, cannot be used as a calibration source for the correction. Radioactive
sources, such as
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Fe, have to be used for collecting correction frames.
