Energy dependence of electron diffraction from a bent wedge crystal of Al was investigated experimentally at energies from 100 KeV to 1 MeV as well as theoretically with particular interest in the systematic interaction. The (222) intensity at the crystal orientation for this reflection is remarkably reduced under observation at some 600 KeV where two dispersion sheets cross each other; furthermore the measured energy-dependence of a fine fringe appearing in the extinction contours agrees fairly well with our theoretical prediction. Around the orientation for (111) reflection the observed profile of (222) image-intensity includes a fringe synchronous to that in the (111) intensity, correspondingly to Vingsbo's observation for an MgO crystal (Proc. 6th International Congress for Electron Microscopy, Kyoto (1966), Vol. I 109.). As for (111) extinction distance, the present theoretical estimation gives a fringe-period shorter by 9% and 16% at 100 KeV and 1 MeV respectively than the simple two-ray approximation does.

Studies are made to investigate the possibility of observing living organs in an electron microscope. An environmental cell is developed, which can be put on an ordinary specimen stage. Microorganisms in pond water are introduced into the environmental cell with water, and observed with a high voltage electron microscope operated at 750 kV. Dynamical image recording is made with a TV system besides stationary film recording. In the environmental cell, the image contrast of the specimen is fairly good, and the image resolution is better than 0.1 µm. Dim images are observed and interpreted as the surface linings of individual cells. The effect of electron irradiation is found to besevere. Future problems for and possibilities with direct observation of living organs are discussed.

The fine structure of a surface defect on GaAs grown by molecular beam epitaxy (MBE) is analyzed by transmission electron microscopy (TEM) observing cross-sectional views of the specimen. The defect has a pyramid structure consisting of four {111} stacking fault planes whose Burgers vectors are a 0/6 <112>, a 0/6 <1̄12>, a 0/6 <11̄2> and a 0/6 <\overline112>. Because a defect of this type always starts at the GaAs substrate surface, the origin is thought to be a point defect or atomic contamination on the surface.

A new method is presented for the composition analysis of GaAs/Al x Ga1-x As multilayer structure using transmission electron microscopy. It is found that the position of equal thickness fringe observed at the edge of a cleaved chip is closely related to the composition. Change in Al composition in GaAs/Al x Ga1-x As superstructure is observed as a shift of the equal thickness fringe. Compositional abruptness at the heterointerface and compositional fluctuation in the thin layer can be estimated in the electron microscope image.

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