Nikolaev K V, Makhotkin I A, Yakunin S N, Kruijs R W E van de, Chuev M A, Bijkerk F
MESA+ Institute for Nanotechnology, University of Twente, The Netherlands.
NRC Kurchatov Institute, Moscow, Russian Federation.
Acta Crystallogr A Found Adv. 2018 Sep 1;74(Pt 5):545-552. doi: 10.1107/S2053273318008963.
Grazing-incidence X-ray diffraction (GID) is a well known technique for the characterization of crystal surfaces. A theoretical study has been performed of the sensitivity of GID to the structure of a crystal surface and distorted nanometre-thin surface layers. To simulate GID from crystals that have a complex subsurface structure, a matrix formalism of the dynamical diffraction theory has been applied. It has been found that the azimuthal rocking curves of a crystal that has a distorted subsurface, measured over a wide angular range, show asymmetric thickness oscillations with two distinguishable sets of frequencies: one corresponding to the diffraction in the single-crystal subsurface layer and the second corresponding to the diffraction in the single-crystal substrate. Therefore, azimuthal rocking curves allow characterization of the subsurface structure of a single crystal. Furthermore, thickness oscillations induced by evanescent diffraction modulate the specular reflection intensity, showing high-intensity modulations. This will potentially allow implementation of subsurface crystal characterization using, for instance, a laboratory-scale X-ray diffractometer.
掠入射X射线衍射（GID）是一种用于表征晶体表面的知名技术。已对GID对晶体表面结构和扭曲的纳米级薄表面层的灵敏度进行了理论研究。为了模拟具有复杂亚表面结构的晶体的GID，应用了动态衍射理论的矩阵形式。已发现，在宽角度范围内测量的具有扭曲亚表面的晶体的方位角摇摆曲线显示出不对称的厚度振荡，具有两组可区分的频率：一组对应于单晶亚表面层中的衍射，另一组对应于单晶衬底中的衍射。因此，方位角摇摆曲线允许表征单晶的亚表面结构。此外，倏逝衍射引起的厚度振荡调制镜面反射强度，显示出高强度调制。这可能允许使用例如实验室规模的X射线衍射仪来实现亚表面晶体表征。
