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EVAL-14: Use at RESI

EVAL-14: Use at RESI. Data reduction process at RESI. Peaksearch and cell determination with Dirax Generation of “shoebox”-files Integration with eval Cell refinement Repeat from 2 until satisfied Data export as cif or shelx-style hkl-file. Basics of EVAL-14.

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EVAL-14: Use at RESI

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  1. EVAL-14: Use at RESI

  2. Data reduction process at RESI • Peaksearch and cell determination with Dirax • Generation of “shoebox”-files • Integration with eval • Cell refinement • Repeat from 2 until satisfied • Data export as cif or shelx-style hkl-file

  3. Basics of EVAL-14 • Developed and maintained by Albert J. M. Duisenberg, Loes M. J. Kroon-Batenburg and Antoine M. M. Schreurs (Utrecht University), distributed by Bruker. • Albert J. M. Duisenberg et al. Intensity evaluation method J. Appl. Cryst. (2003). 36, 220-229 • Prediction of peak position and shape by ray-tracing.

  4. Factors influencing the peak shape • The source: Size, Divergence and wavelength distribution • The sample: Mosaic, crystal shape+aligment

  5. Source description • Rectangular shape at fixed distance • For neutron case: fixed single wavelength • (x-ray: α1/ α2)

  6. Crystal description • Sphere with radius r or • Rectangular block enclosing the actual shape • Mosaic spread • Possibly anisotropic moasic

  7. Generating the profile • Simplification of the 3-D profile by only looking at the projections along w, XD,YD • Contours generated by sub-profile addition

  8. The integrated intensity • Preduction to “shoeboxes” • With the final contour: Background-Peak-Background (BPB) integration • For strong reflections shifting of the final peak position

  9. Advantages • Works in the absence of strong “model reflections” • Can model anisotropic mosaic or diffuse streaking • Works in the presence of “alien” reflections (e.g. twins, other phases, multigrain crystals) • Many parameters to tune

  10. Disadvantages • Quite computing intensive • Many parameters to tune • Commercial software

  11. Detector image

  12. ”Shoeboxes” in the integration view

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