The Wells effect in precession photography
Abstract
Loci of high absorption are derived for very thin plates in precession photography. Reflections lying on loci of the first kind have been attenuated by being diffracted along the plane of the plate; those lying on loci of the second kind are attenuated because they arose as the incident beam lay in the plane of the plate.
The loci of the first kind are two circles disposed on that film diameter which is parallel to the plane of the plate. These circles are of the same diameter on all levels. The loci of the second kind are two circles disposed along the same line, but having a diameter equal to that of the Laue cone at the film. The blind spot at the center of the film is externally tangent to the loci of the first kind, but is internally tangent to the loci of the second kind. Both kinds of loci, on the other hand, are tangent to the boundary of the region of reciprocal space being recorded. On the zero level, the loci for both absorption mechanisms coincide.
Procedures for eliminating absorption effects are proposed. If the absorption effects are not removed, the loci constitute but a small fraction of the region of reciprocal space recorded. When located, they readily indicate the reflections which should be omitted from a structure refinement.
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Articles in the same Issue
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- Ordnung/Unordnung und Ultrarotabsorption IV. Die Absorption einiger Metalloxyde mit Spinellstruktur
- The Wells effect in precession photography
- Kristallstrukturuntersuchungen an ZnCl21
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- The effect of soft x-rays on azides of potassium azide type structures
- Zur thermischen Umwandlung und Kristallographie von Petalit und Spodumen
- Hydrothermale und röntgenographische Untersuchungen an gesteinsbildenden Mineralen, VI Über hydrothermal hergestellten triklinen K-Feldspat1
- The crystal structure of mordenite (ptilolite)*
- The crystal structure of xanthates II. Antimonious xanthate
- A new structural type of metaborate anion
- On the occurrence of a two-layer orthorhombic stacking polymorph of lepidolite
- Härtekennwerte gefärbter Flußspatkristalle
- Eine Serie von IBM 650-Programmen zur Kristallstruktur-Bestimmung
- Max Von Laue, Gesammelte Schriften und Vorträge.
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- Fünfzig Jahre Röntgeninterferenzen
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