抄録
The simultaneous reflexion by two lattice planes (with indices h and h′) in electron diffraction has been treated by the dynamical theory in order to investigate how it is influenced by the phases of structure amplitudes. For convenience of treatment, a modified formulation of the theory has been developed using particular cross sections of the dispersion surface in reciprocal space. Applying the theory to a lamellar crystal, it was proved that the intensities of transmitted and diffracted waves depend in a relatively simple way on the value of |Φhh′|=|\varphih−\varphih′+\varphih′−h|, where \varphih, \varphih′, and \varphih′−h are the phase angles of structure amplitudes for the indices h, h′, and h′−h. It was shown that the phase effect can be most easily demonstrated by observing fine structures of reflexion spectra which are obtained by rotating the crystal in a specified manner. The determination of the value of |Φhh′| is most simple when the coupling reflexion h′−h is strong compared with the reflexions h and h′, and the crystal is centrosymmetric.
