Anomalous dispersion refinement

(due to) A. van Donkelaar, CSIRO Health Sciences

SYNOPSIS: The high signal-noise ratio produced by the PX50 system permits the refinement of anomalous dispersion factors by collecting redundant orientations from specimens possessing high symmetry.

Crystals of heavy-atom-derivative molecules exhibiting good diffraction characteristics and high crystal symmetry may be used to refine anomalous dispersion factors by collecting data from the full 360° of oscillation range. The anomalous signal is amplified by the sampling of all the equivalent symmetries and is NOT equivalent to the re-collection of redundant datasets from the same symmetry axis of the specimen.

Note: It is essential to collect all data from the same crystal using the same orientation matrix. An orientation matrix should be established from one symmetry zone of the crystal before proceeding to other zones.

(c) Copyright AXCO 2004