The theory of image formation by a high-resolution electron microscope is reviewed based on the wave-optics. The image formation in an electron microscope is characterized by strong interaction of electrons as well as a large spherical aberration of an objective lens. Thus the interference between scattered waves at recording an image becomes important. Ananalvtical expression of the transmission-cross-coefficient is derived, which describes the degree of coherence between each two scattered waves due to the aberrations. The transmission-cross-coefficients control the information transfer through the electron microscope, and thus limit the attainable resolution of the microscope. The characteristics of high-resolution electron microscopy will be made clear by comparison with optical microscopy.
Ice Ih is a famous crystal which retains residual entropy. The corresponding glass transition exists around 100 K. A 1st-order phase transition observed in ice crystals doped with alkali hydroxides removed a substantial fraction of the residual entropy. A neutron diffraction experiment confirmed an ordered pattern of proton location. The conceptual significance of these experimental findings is discussed in relation to the ordering processes in disordered systems in an equilibrium experiment [J. Cryst. Soc. Jpn. 28, 16 (1986) ] .
Lead (II) iodide-Lewis base adducts change their structure a variety of ways by altering the base. The Structures are discussed on the basis of the nature of each Lewis base. The structural diversity is also connected with an existence of a stereochemical active‘inert 6s2 pair’electrons of Pb (II) atom which is affacted from coordinated Lewis base. [J. Cryst. Soc. Jpn, 28, 26 (1986) ] .