Intensity enhancement in asymmetric diffraction with parallel-beam synchrotron radiation

Abstract

An intensity enhancement obtained from asymmetric diffraction with a fixed incident angle a has been studied. Parallel-beam synchrotron radiation with 2 = 1.54 A (Stanford Synchrotron Radiation Laboratory) and 2 = 1.53 A (Photon Factory) was used to collect powder diffraction patterns of Si, CeO2 (a = 5 and 10 °) and monoclinic ZrO2 (a = 10°). The synchrotron-radiation data were analyzed using singlereflection profile fitting and whole-powder-pattern fitting techniques. The integrated intensities in the asymmetric diffraction were compared with those of symmetric diffraction obtained by the conventional 0-20 scanning technique. An intensity, after correction for a limited height of counter aperture, was enhanced by factors of 1.8 (a=5 °) and 1.7 (a=10 °) at the maximum in asymmetric diffraction and its magnitudes agreed well with those calculated from theory.

A New Powder Diffractometer for Synchrotron Radiation with a Multiple-Detector System

“…The diffracted intensity in asymmetric diffraction is enhanced compared with that in symmetric diffraction, and its intensity ratio is given by 2/(1 + sin odsin/3) (Toraya et al, 1993b). The observed intensity ratio for the (111) reflection from Si was 1.61, and agrees well with the calculated value of 1.64.…”

“…The f, ft and f" tables for Mf ÷ and Si 4÷ were taken from International Tables for Xray Crystallography (1974) and an f table for 02-given by Tokonami (1965). The integrated intensity was corrected for Lorentz and polarization effects (Cox, 1992), the intensity enhancement in asymmetric diffraction (Toraya, Huang & Wu, 1993b), the intensity reduction arising from the limited dimensions of the detector system, and the preferred orientation. The preferred orientation was corrected by the function of symmetrized harmonics expansion (Jarvinen, 1993).…”

Rietveld analysis using powder diffraction data with anomalous scattering effect obtained by focused beam flat sample method

“…After translation of obtained diffraction data to 2 -intensity format, asymmetric diffraction correction, which is, correspond to the correction of the absorption effect of the FFM [10,11] was performed by an originally developed program. A Rietveld refinement program, PFLS.exe [12] were used for structure refinements.…”

Long Horizontal Parallel Slits with 0.03° Angular Resolution for Powder Diffraction Using Synchrotron Radiation

“…It has two main purposes. One is to achieve 0.03 ° angular resolution and the other is to stack the foils to a height of 25 mm, which is required for asymmetric 20 scanning at a fixed incident angle (Toraya, Huang & Wu, 1993).…”