A quantitative analysis of the cone-angle dependence in precession electron diffraction

作者：Ciston J^*; Deng B; Marks L D; Own C S; Sinkler W

来源：Ultramicroscopy, 2008, 108(6): 514-522.

DOI：10.1016/j.ultramic.2007.08.004

• precession electron diffraction
• bulk charge density
• kinematical extinction
• multislice simulation

Precession electron diffraction (PED) is a technique which is gaining increasing interest due to its case of use and reduction of the dynamical scattering problem in electron diffraction. To further investigate the usefulness of this technique, we have performed a systematic study of the effect of precession angle on the mineral andalusite where the semiangle was varied from 6.5 to 32 mrad in five discrete steps. The purpose of this study was to determine the optimal conditions for the amelioration of kinematically forbidden reflections, and the measurement of valence charge density. We show that the intensities of kinematically forbidden reflections decay exponentially as the precession semiangle (phi) is increased. We have also determined that charge density effects are best observed at moderately low angles (6.5-13 mrad) even though PED patterns become more kinematical in nature as the precession angle is increased further.

• 出版日期2008-5
• 单位西北大学