X射线双晶衍射摇摆曲线本征半峰宽的理论计算

本文应用X射线衍射动力学理论,推导出Bragg衍射几何X射线双晶衍射反射率的数学表达式。多种晶体、不同衍射的摇摆曲线计算结果表明,σ偏振的摇摆曲线的峰值和积分强度均比π偏振的高。而且半峰宽较宽。同时指出,对圆偏振X射线入射或者A,B两晶体不同类或者两者的衍射级数不相同时,很多文献给出的双晶衍射摇摆曲线半峰宽的近似表达式2^1/2∞不再适用。 关键词：

THEORETICAL CALCULATION OF THE ROCKING CURVE FOR X-RAY DOUBLE CRYSTAL DIFFRACTION

Using the X-ray dynamical theory, the reflection coefficients of X-ray double crystal diffraction in Bragg case were derived. The results of the rocking curves calculated for different kind of crystals and different diffractions show that the peak value and the integral intensity of rocking curve for σ polarization are higher than those for π polarization. And the full width at half maximum (FWHM) of σ polarization is wider than that of π polarization. It is pointed out that when the incident X-ray beam is a circle polarized one or/and the crystals A and B are different kind of crystals or/and the diffraction vector of A is different from that of B, the approximative expression of the FWHM of rocking curve for double crystal diffraction, 2^1/2∞, which was used by many authors, is invalid.