The analysis procedure of valence-electron excitation spectra is described with an example of diamond. It includes a subtraction of zero-loss intensity, a deconvolution of multiple inelastic scattering intensities, a derivation of a loss-function, Kramers-Kronig analysis and a calculation of optical constants. A split of inner-shell electron levels due to the spin-orbit interaction and the crystal-field splitting of 3d electron orbital energies are explained with an example of VO2 spectra. A development of an X-ray emission spectroscopy instrument for a transmission electron microscopy to obtain a density of states of valence bands is briefly described.
Microanalysis using electron energy-loss spectroscopy (EELS) in transmission electron microscope (TEM) is briefly reviewed. The method and the experimental results of elemental mapping and chemical analysis are shown. The detection limit, spatial resolution and practical aspects in TEM-EELS are also presented.
X-ray magnetic diffraction experiment of ferromagnets that utilizes elliptically polarized synchrotron radiation is presented. First we have reviewed shortly historical backgrounds and theoretical aspects of the experiment. We have presented how the magnetic form factors are measured and are separated into the spin-moment component and the orbital-moment component in this experiment. Peculiar features of the polarization factor of this experiment have been explained. We have introduced two examples of the experiment. One is the measurement of the spin-magnetic form factor of SmAl2 with white X-rays from a bending magnet at the Photon Factory. The other is the measurement of the orbital-magnetic form factor of Holmium Iron Garnets with monochromatic X-rays from an undulator at the SPring-8. Finally we summarize the article and show some future prospects of this experiment.
Strict recognition of both tRNA and amino acid by aminoacyl-tRNA synthetase is essential for the faithful protein biosynthesis. We have determined a crystal structure of Thermus thermophilus glutamyl-tRNA synthetase (GluRS) in complex with its cognate tRNAGlu. The structure provided the molecular basis of strict tRNA recognition by GluRS and insights into evolution of the enzyme anticodon specificity.
The combination of RIETAN-2000 and a new MEM analysis program PRIMA enables us to represent crystal structures with densities of electrons (X-ray diffraction) or coherent-scattering lengths (neutron diffraction) instead of structure parameters in Rietveld analysis. We have devised sophisticated methodology named MEM-based pattern fitting, where whole-pattern fitting and MEM analysis are alternately repeated to reduce the bias of a structural model in Rietveld analysis as much as possible. Applications of MPF to some compounds will be demonstrated. A 3D visualization program VENUS serves to display and manipulate electron and scattering-length densities, electrostatic potentials, wave functions, and so forth.
The Pharmaceutical Industry Beamline was constructed by the Pharmaceutical Consortium for Protein Structure Analysis which was established in April 2001. The consortium is composed of 22 pharmaceutical companies affiliating with the Japan Pharmaceutical Manufacturers Association. The beamline is the first exclusive one that is owned by pharmaceutical enterprises at SPring-8. The specification and equipments of the Pharmaceutical Industry Beamline is almost same as that of RIKEN Structural Genomics Beamline I & II.