ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
On the basis of some mathematical and physical characteristics of anomalous dispersion experiments, it has been possible to derive simple rules, Rano, 1, Rano, 2 and Rano, 3, that permit the selection of triplet phase invariants, in a single-wavelength experiment, that have values close to π/2, -π/2, 0 and other values in the range from -π to π. The rules, Rano, 1, Rano, 2 and Rano, 3, apply to the case of a single type of predominant anomalous scatterer. The simple generalization to more than one type of predominant anomalous scatterer is also described. Test examples show that large numbers of invariants may be evaluated by these means with reliabilities that are potentially high, but depend, of course, on the reliability of the experimental data. The only information required besides the measurements of the diffraction intensities is the chemical composition of the anomalously scattering atoms. In some cases, even this information is not required if two alternative sets of estimates of the values of the triplet phase invariants are considered.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0108767384000027
