Anisotropic dispersion of the band structure and formation of ring patterns in CBED.
An off-axis ring pattern was observed in the <1-11> zone-axis CBED pattern of an NiO single crystal. The pattern was interpreted as resulting from anisotropic dispersion of the band structure of the two most strongly excited free Bloch waves and strong absorption of the most tightly bound 1s Bloch state. Comparison has also been made with the case of MgO which has the same structure as NiO but weaker scattering power. The tightly bound 1s Bloch state in MgO was found to play an important role together with a strongly excited free Bloch state and a more conventional zone-axis ring pattern similar to that observed in the <001> zone-axis CBED pattern of silicon was observed.
Peng
LM
Department of Electronics, Peking University, Beijing 100871, People's Republic of China, and Beijing Laboratory of Electron Microscopy, Center for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, PO Box 2724, Beijing 100080, People's Republic of China. lmpeng@lmplab.blem.ac.cn
Zuo
JM