The Debye–Scherrer camera at synchrotron sources: a revisit

Abstract

In a powder diffraction pattern one measures the intensity of Miller-indexed Bragg peaks versus the wavevector transfer sinθ/λ. With increasing wavevector transfer the density of occurrence of Bragg peaks increases while their intensity decreases until they vanish into the background level. The lowest possible background level is that due to Compton scattering from the powder. A powder diffraction instrument has been designed and tested that yields this ideal low-background level, obtainable by having the space between sample and detector all in vacuum with the entrance window so far upstream that scattering from it is negligible. To minimize overlap of Bragg peaks the combination of fine collimation of synchrotron radiation, a thin cylindrical sample and a high-resolution imaging plate detector is taken advantage of.

Experimental determination of core electron deformation in diamond

“…In order to facilitate high-resolution PXRD, roomtemperature data were collected at the P02.1 beamline at PETRA III, Germany, using an all-in-vacuum diffractometer. The details of the diffractometer along with data-reduction procedures are described in Straasø et al (2013). The wavelength was derived by measurements on a silicon single crystal (a = 5.4309 Å ) to be 0.20687 (2) Å .…”

“…Because of proper integration of the Debye-Scherrer arcs (Straasø et al, 2013), the peak-shape calculations included no asymmetry model and the peaks were cut at 30 times the full width at halfmaximum (FWHM). An essential feature of the collected PXRD data is their highly narrow, constantly well separated peaks with an FWHM varying merely from 0.04 to 0.05 .…”

“…With this in mind, a new all-in-vacuum powder diffractometer was designed and commissioned. Initial measurements indeed showed a significant increase in the signal-to-noise ratio of the reflections as well as background intensity close to its fundamental limit (Straasø et al, 2013).…”

Visualizing charge densities and electrostatic potentials in materials by synchrotron X-ray powder diffraction

“…The concept has inspired other beamlines at SPring-8, such as BL44B2 [11] and BL15XU [12] for materials scientists, and BL19B2 [13] for industrial users, to employ the Debye-Scherrer method. Furthermore, the powder diffraction beamline at Australian Synchrotron [14] and a vacuum-type Debye-Scherrer camera [15] have been facilitated by successful experiments at SPring-8 powder diffraction beamlines.…”

“…Note that the waiting time depends on the type of imaging plate, that is the fluorescence material and its thickness. Another approach with a decay curve fitting to the fading effect has been examined by Straaso et al [15], in which case there is no need to wait for a long time but need to record time for the data correction. The spatial resolution of the imaging plate is determined by the scanning speed of the read-out system and the error of ±0.1% or so seems to be unavoidable.…”