ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
This paper studies in detail `tilted reflections', which are defined here as Bragg reflections where the incident vector k(a)o, the diffraction vector h and the normal n to the surface are not coplanar. Such reflections are especially useful when it is necessary to work in Bragg geometry with reflecting planes making an angle Φ with the crystal surface that is larger than the Bragg angle. It is shown that the usual expressions of X-ray dynamical theory can still be applied if the vector n normal to the crystal surface is replaced by its projection n' on the diffraction plane (h,k(a)o) (except naturally when n' is a null or nearly null vector). By rotation of the crystal surface around the diffraction vector, one can then go from transmission cases to reflection ones with various asymmetry factors. Tilted reflections are used in X-ray standing-wave experiments to triangulate atomic positions. It is shown and illustrated by experimental results that an accurate determination of the asymmetry factor is then necessary for correct analysis of the results.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0108767394001637
