Intensity enhancement in asymmetric diffraction with parallel-beam synchrotron radiation

An intensity enhancement obtained from asymmetric diffraction with a fixed incident angle α has been studied. Parallel-beam synchrotron radiation with λ = 1.54 Å (Stanford Synchrotron Radiation Laboratory) and λ = 1.53 Å (Photon Factory) was used to collect powder diffraction patterns of Si, CeO₂ (α = 5 and 10°) and monoclinic ZrO₂ (α = 10°). The synchrotron-radiation data were analyzed using single-reflection 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 θ–2θ scanning technique. An intensity, after correction for a limited height of counter aperture, was enhanced by factors of 1.8 (α = 5°) and 1.7 (α = 10°) at the maximum in asymmetric diffraction and its magnitudes agreed well with those calculated from theory.