This article is the first introduction to transmission electron microscopy (TEM) for beginners interested in the crystal structure analysis by means of electron diffraction and highresolution electron microscopy. Brief history of TEM, basic arrangements of TEM instruments, how to obtain selected area electron diffraction patterns, and how to prepare specimen by “crushing method”, are described.
Recent development in the techniques for the X-ray structural analysis of synthetic polymer crystals have been reviewed with some illustrations. In particular the usefulness of imaging plate system has been stressed and a new software for collecting quantitative data of the position and integrated intensity of the observed reflections has been introduced, which enabled us to apply the so-called direct method to the construction of the initial structural models necessary for the structural refinement. The structural changes of polymer crystals caused by an application of tensile force or by a temperature change have been discussed for two cases of polydiacetylene giant crystal and orthorhombic polyethylene.
Principles and applications of ultrafast laser spectroscopy are reviewed. The time-domain spectroscopy is suitable to investigate the low frequency modes which are closely connected with the dynamical behaviors and structural fluctuations of condensed matters.
Dithioketopyrrolopyrrole (blue pigment) is known to crystallize in three crystal phases I, II and III, among which only modification III exhibits an intense near-IR absorption. The mechanism of the near-IR absorption has been discussed on the basis of the crystal structure and exciton coupling effects. The J-aggregate-like molecular stack characterized by “bricks in a brick wall” is found to be responsible for the near-IR absorption. The switching of the near-IR absorptin by forming or disturbing the J-aggregate-like structure can be applied to an optical disk of the “write once” type. The disk developed exhibits a reflectivity change from about 30% to 45% on writing with a power of about 9mW at 780nm.
We have studied the structural properties of the dipole glass using X-ray diffraction and EXAFS measurements to elucidate the mean and local structure of the dipole glass. In the glassy state, the local distortion of a lattice with only short-range correlation is induced by the reorientational freezing of molecules having the dipole moment. The anomalous behavior, such as the integrated intensity of the diffuse scattering, is explained by the Edwards-Anderson cluster theory.