Towards extinction-free experimental diffraction data on Al₂O₃

Abstract

Using 58keY (0.214,~) synchrotron radiation we have obtained virtually extinction-free data on A1203. Refinement of a multipole model against these data produced deformation densities of high quality, which compare well with theoretical maps.

Local structure and disorder in crystalline Pb9Al8O21

“…12. The measured total correlation function (thick line), T exp (r), for our sample, together with the simulated correlation function (thin line), T sim (r), calculated from our structural data for Pb 9 Al 8 O 21 and literature data for a-Al 2 O 3 [57]. The dashed line shows the a-Al 2 O 3 contribution to T sim (r).…”

“…The correlation function of a-Al 2 O 3 , corundum, was calculated using the reported lattice parameters and atomic coordinates [57], together with the same thermal widths as used for Pb 9 Al 8 O 21 . The simulated correlation function for our sample, T sim (r), was then calculated as the weighted sum of the correlation functions of the two individual phases, according to Eq.…”

Agostische Wechselwirkungen in d0‐Alkylmetallkomplexen

“…B. Flächenzähler, Tieftemperatur‐Probenumgebungen und kurzwellige Röntgenstrahlung in Kombination mit kleinen Kristallen hoher Qualität 24. Zudem bieten Experimente bei unterschiedlichen Wellenlängen oder die Verwendung von γ‐Strahlungsquellen25a die Möglichkeit, durch Extrapolation auf die Wellenlänge von 0 Å Absorptionseffekte zu minimieren und extinktionsfreie Daten zu erhalten 25b. Trotz all dieser Ansätze sind Abweichungen von mehr als 0.1 Å zwischen den so erhaltenen M⋅⋅⋅H‐Bindungslängen und den bei Neutronenbeugungsstudien erhaltenen Werten immer noch üblich.…”

CCD Charge Density Study on Crystals with Large Unit Cell Parameters: The Case of Hexagonall-Cystine

“…Two-dimensional (2D) detectors like CCD or imaging plates (which are widely used in protein crystallography) are also becoming more and more popular for small molecule structure determinations (2−24 h data collection). However, until recently very few electron density studies have been obtained from 2D-detector data. − …”