Several single crystal CVD diamonds with (001) and (111) surface orientations were studied using x-ray diffraction rocking curve mapping in the double-crystal pseudo plane-wave configuration using Bragg reflection geometry. Strongly nonuniform distributions of rocking curve parameters on the studied crystal surfaces were observed, which indicates that the crystals exhibit substantial lattice distortions. Selected crystal pairs were tested in the nondispersive double-crystal configuration using polychromatic bending magnet synchrotron radiation. The results suggest that CVD diamond crystals could be used as high-flux broadband x-ray monochromators in applications where preservation of the radiation wavefront is not a primary goal.
The small, high intensity and low convergence beams available on beamlines at 3rd generation synchrotron sources have been a
boon to macromolecular crystallography. It is now becoming routine to solve structures using a beam in the 5 - 20 micron
(FWHM) range. However, many problems in structural biology suffer from poor S/N due to small (a few microns) crystals or
larger inhomogenous crystals. In additional, theoretical calculations and experimental results have demonstrated that radiation
damage may be reduced by using a micron-sized X-ray beam. At GM/CA CAT we are developing a sub-micron, low convergence
beam to address these issues. The sub-micron beam capability will be developed on the existing beamline 23ID-D where the
minimum beam size available to users is currently 5 microns in diameter. The target goals are a beam size of ~0.8 micron
(FWHM) in diameter, with a beam convergence of less 0.6 milli-rads, a flux greater than 5×1010 photons/sec, and an energy range
from 5 to 35 keV. Five optical systems will be compared: 1) a single set of highly demagnifying Kirkpatrick-Baez (K-B) mirrors,
2) multiple Fresnel Zone Plates (FZP), 3) a set of K-B mirrors focusing to a secondary source that is imaged by another set of K-B
mirrors, 4) a set of K-B mirrors focusing to a secondary source that is imaged by a FZP, 5) a horizontal focusing mirror focusing
to a secondary source that is imaged by another horizontal mirror together with a vertical focusing mirror. Here we will present
the results of a design optimization based on ray trace simulations (SHADOW), flux calculations (XOP), and experimental results
on 23ID.
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