Bikondoa Oier, Carbone Dina
Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom.
MAX IV Laboratory, Fotongatan 2, 225 94 Lund, Sweden.
J Synchrotron Radiat. 2021 Mar 1;28(Pt 2):538-549. doi: 10.1107/S1600577521000722. Epub 2021 Feb 18.
Compton scattering is generally neglected in diffraction experiments because the incoherent radiation it generates does not give rise to interference effects and therefore is negligible at Bragg peaks. However, as the scattering volume is reduced, the difference between the Rayleigh (coherent) and Compton (incoherent) contributions at Bragg peaks diminishes and the incoherent part may become substantial. The consequences can be significant for coherent diffraction imaging at high scattering angles: the incoherent radiation produces background that smears out the secondary interference fringes, affecting thus the achievable resolution of the technique. Here, a criterion that relates the object shape and the resolution is introduced. The Compton contribution for several object shapes is quantified, and it is shown that the maximum achievable resolution along different directions has a strong dependence on the crystal shape and size.
在衍射实验中，康普顿散射通常被忽略，因为它产生的非相干辐射不会产生干涉效应，因此在布拉格峰处可忽略不计。然而，随着散射体积的减小，布拉格峰处瑞利（相干）和康普顿（非相干）贡献之间的差异会减小，非相干部分可能会变得显著。这对于高散射角下的相干衍射成像可能会产生重大影响：非相干辐射产生的背景会模糊二次干涉条纹，从而影响该技术可达到的分辨率。在此，引入了一个将物体形状与分辨率相关联的判据。对几种物体形状的康普顿贡献进行了量化，结果表明，沿不同方向可达到的最大分辨率强烈依赖于晶体的形状和尺寸。
