Acquisition of powder diffraction data with synchrotron radiation [electronic resource].
- Upton, N.Y. : Brookhaven National Laboratory, 1987.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
- Physical Description:
- Pages: 32 : digital, PDF file
- Additional Creators:
- Brookhaven National Laboratory
United States. Department of Energy. Office of Scientific and Technical Information
- During the past year, a dedicated triple-axis powder diffractometer has been in routine operation at the Brookhaven National Synchrotron Light Source as a user-oriented facility. The diffractometer is designed to allow easy interchange between energy-dispersive and monochromatic beam experiments. In the latter mode of operation, high resolution data have been collected for a variety of samples with the use of the crystal-analyzer technique, and in several cases these data sets have been used successfully for structure solution and Rietveld refinement. Several aspects of data acquisition at a synchrotron beam-line are described, and some of the different types of scattering geometry which have been used are discussed. Simple expressions are given for the instrumental resolution function expressed as the angular variation of peak widths for each of these. The peak shapes observed for a reference sample of Si on the present triple-axis instrument are well-described by the convolution of Gaussian and Lorentzian functions, and the angular dependence of the Gaussian component is in excellent agreement with the corresponding calculated instrumental function. One of the most important considerations for each type of experiment is the necessary compromise between intensity and resolution over a wide range of scattering angles, and some of the available options will be discussed. In particular, the use of Ge(440) and LiF(400) analyzer crystals gives a focussing minimum at relatively high angles (2 THETA approx. = 50/sup 0/ at 1.54A), a highly desirable feature for Rietveld analysis of complex structures. Absolute intensities from reference samples of Si and CeO/sub 2/ are calculated for these and several other scattering configurations involving both flat-plate and capillary geometry to illustrate this compromise. 26 refs., 3 figs., 3 tabs.
- Published through SciTech Connect.
International symposium on X-ray powder diffractometry, Fremantle, Australia, 20 Aug 1987.
Cox, D.E.; Eddy, M.M.; Toby, B.H.
- Funding Information:
View MARC record | catkey: 14402176