Tivol W F
Wadsworth Center for Laboratories and Research, School of Public Health, Albany, NY 12201-0509, USA.
Acta Crystallogr A. 1995 Sep 1;51 ( Pt 5):708-16. doi: 10.1107/s0108767395003278.
Unitarity, a fundamental principle of scattering theory, leads to the prediction of an essentially unique set of phases for the scattering amplitude from a complete knowledge of the differential cross section or, in the case of a crystal, from the diffracted intensities. The Sayre equation and all the direct methods of phasing following there from are derived as a special case of unitarity for zero excitation error. Dynamical and kinematical scattering are considered, and the relationship between them, S = exp(i tau nzK), is obtained. Applications to the case of electron diffraction including for non-zero excitation error are discussed.
幺正性是散射理论的一个基本原理，基于对微分截面的全面了解，或者在晶体的情况下，基于对衍射强度的了解，它能预测散射振幅的一组本质上唯一的相位。塞尔方程以及由此推导出来的所有直接相位确定方法，都是作为零激发误差情况下幺正性的一个特殊情况而得出的。文中考虑了动力学散射和运动学散射，并得到了它们之间的关系S = exp(iτnzK)。还讨论了其在电子衍射情况中的应用，包括非零激发误差的情况。
