Recently, it was found that amorphization is induced in silicon by electron irradiation. By systematic examinations, it was clarified that MeV electron irradiation at low temperature below 100 K is necessary for the amorphization. The result means that the amorphization is caused by the accumulation of not point defects but small cascade damages. Moreover, from precise analysis of the dependence of the intensity of halo rings on irradiation energy and dose, it is concluded that the smallest cascade damage that contributes to amorphization includes only about four silicon atoms. Since amorphous silicon (a-Si) induced by electron irradiation is similar to a-Si created by other conventional techniques, there is a possibility that the new amorphization technique by electron beam is also applied to fabricating various artificial Si structures.
Short-range order (SRO) in Ni-Mo alloys and their relatives has been controversial for decades, since it causes clearly diffraction intensity maxima at positions which do not coincide with the superlattice reflections in the long-range order (LRO) state. This paper gives an overview of recent studies on the structure of SRO and the transition from SRO to LRO in Ni-Mo alloys, including our results obtained in atomic level by combination of kinetic Monte Carlo simulation and semi-quantitative high-resolution transmission electron microscopy. It is rationalized in our results that the SRO state is set up by local ordering of A4B, A3B and A2B types in sub-unit cell scale. The dispersed mixture of the sub-unit cell clusters gives diffraction intensity maxima at the particular positions. An LRO state is formed by selected growth of the A4B, A3B and A2B type clusters into LRO domains depending on alloy-com-position.
Electron microscopy and spectroscopy with the single-atom sensitivity enables us to obtain a direct image of the intra-molecular structure and chemical identification of individual metallofullerenes encapsulated inside single-walled carbon nanotubes, so-called peapods. By a comparison of high resolution images with a simulation to extract the relative atom positions for encaged metal atom in each molecule, distribution of molecular orientation and its interaction between adjacent molecules in metallofullerene-peapods have been statistically analyzed. Moreover the techniques described here demonstrates the possibilities to observe individual chemical reaction inside carbon nanotubes.
1H NMR studies and X-ray analysis elucidated the structure of a cation-π complex of a compound containing a pyridinium and a phenyl ring. The existence of intramolecular interactions between a pyridinium and a thiocarbonyl or a carbonyl was also elucidated. Moreover, the intermolecular interactions for the both systems were observed in crystalline state. The selective shielding of one side of the pyridinium face by way of intramolecular interaction enabled nucleophiles to attack only from the non-shielded side, and consequently, chiral 1, 4-di-hydropyridines were produced stereoselectively.
RIETAN-2000/2001T are connected with several related programs via a variety of text files for cooperative crystallographic computation and visualization. Contents of input and out-put files of RIETAN are explained for its full utilization. The knowhow of measuring reliable powder diffraction data recorded in *.int and parts of data in the user-input file, *. are described particularly in detail.