Inui Haruyuki, Fujii Akihiro, Tanaka Katsushi, Sakamoto Hiroki, Ishizuka Kazuo
Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
Acta Crystallogr B. 2003 Dec;59(Pt 6):802-10. doi: 10.1107/s010876810302411x. Epub 2003 Nov 25.
A new CBED (convergent-beam electron diffraction) method is proposed for the identification of the chirality of enantiomorphic crystals, in which asymmetry in the intensity of the reflections of Bijvoet pairs in an experimental symmetrical zone-axis CBED pattern is compared with that of a computer-simulated CBED pattern. The intensity difference for reflections of these Bijvoet pairs results from multiple scattering (dynamical nature of electron diffraction) among relevant Bijvoet pairs of reflections, each pair of which has identical amplitude and different phase angles. Therefore, the crystal thickness where chiral identification is made with the present method is limited by the extinction distance of Bijvoet pairs of reflections relevant to multiple scattering to produce the intensity asymmetry, which is usually of the order of a few tens of nanometers. With the present method, a single CBED pattern is sufficient and chiral identification can be made for all the possible enantiomorphic crystals that are allowed to exist in crystallography.
提出了一种用于鉴定对映体晶体手性的新的会聚束电子衍射（CBED）方法，该方法将实验对称区轴CBED图案中Bijvoet对反射强度的不对称性与计算机模拟的CBED图案的不对称性进行比较。这些Bijvoet对反射的强度差异源于相关Bijvoet对反射之间的多重散射（电子衍射的动力学性质），每对反射具有相同的振幅和不同的相位角。因此，用本方法进行手性鉴定的晶体厚度受到与多重散射相关的Bijvoet对反射的消光距离的限制，以产生强度不对称，其通常为几十纳米量级。用本方法，单个CBED图案就足够了，并且可以对晶体学中允许存在的所有可能的对映体晶体进行手性鉴定。
