The present status is reviewed of the gaseous electronics, with particular emphasis on the behaviour of a swarm of slow electrons (generally below a few eV) liberated in a gas and separated from positive ions. After describing briefly the history and the present significance of the field, various processes of generation and loss of swarm electrons are summarized, though in some detail for the attachment process. This is followed by a discussion of transport phenomena such as the drift and the diffusion with reference to the drift velocity and the characteristic energy of swarm electrons. Mention is made of the anisotropy of diffusion under an electric field and of the diffusion cooling in non-uniform swarms. Recent data on the characteristic energy in mixed gases are presented and discussed. Finally, after surveying the previous attempts to infer the velocity distribution of electrons under an electric field, a new method is proposed to investigate the distribution in mixed gases.
Single crystals of ZnSe grown by the Bridgeman method under high, inert gas pressure contain many lattice defects; for example, the stacking fault is predominant in the crystals grown by the authors. To clarify the relationship between the shapes of etch pits and crystallographic polarity, the etch pits and the light figures were observed and furthermore the ratio of scattered X-ray intensities, FF* (hkl)/FF* (hkl) were examined. From our experimental results, it was confirmed that the plane of flat bottomed triangular pits and that of deep triangular pits corespond to A (111)Zn and B (111)se surfaces, respectively.
A theory is developed for a new method in -holography, in which the image is directly obtained from diffraction integral using the convolution theorem. According to the theory described here, it is shown that an aberration-free image can be reconstructed. It is noteworthy that this theory can be applied to computer reconstruction for long-wavelength holography.