In electron holography, electron holograms are characterized by specimen images and interference fringes superimposed thereon. This characterization is essentially the same as that used in 2D-image data treatments in a fringe analysis method. Utilizing this method several phase reconstruction methods have been introduced; among these, the phase-shift method is most advanced for electron holography. In this paper we discuss the principle of the phase-shift method, its optical systems and algorithms together with applications to magnetic materials analysis.
Enantiomers, or stereoisomers, have crystal structures that are mirror images of each other and are thus handed, like our right and left hands. Low-quartz（SiO2）and Berlinite（AlPO4）have enantiomers belonging to a space-group pair, P3121（right-handed screw）and P3221（left-handed screw）. We show that resonant Bragg diffraction using positive and negative circularly polarized X-rays at the resonant energies reveals the handedness of crystals by X-ray helicity coupling to a crystal screw axis. Our results are of general importance and demonstrate a new method to directly study chiral motifs in structures that include biomaterials, liquid crystals, magnets, multiferroics, etc.
We report enantiopure crystal growth and chiral helimagnetic ordering in chiral inorganic compounds CsCuCl3 with a chiral space group of right-handed P6122 or left-handed P6522. Our 2-step crystallization process makes it possible to grow centimeter sized enantiopure single crystals. Polarized neutron diffraction experiments probed that crystallographic chirality of CsCuCl3 strongly combined with helimagnetic chirality via Dzyalloshinskii-Moriya interaction.
Molecular chirality realizes strongly in the condensed phases（crystals, membranes, gels）, however, it cannot be generally measured by commercially-available spectrophotometers due to strong macroscopic anisotropies. We have developed novel Universal Chiroptical Spectrophotometers, UCS-1～3, which overcome these problems. UCS-1 provides all optical characteristics. UCS-2/3 measure transmittance and Diffuse Reflectance CD, with vertical incident light and a horizontal sample stage, ideal for a droplet of solutions, loose powders or gel, to reveal structures and the dynamics of the transition processes. In this article, I shall describe the difficulty of solid-state chirality measurements, principles/outlines of UCSs and several examples of rich information obtained using UCSs.
A vacuum-ultraviolet circular-dichroism spectroscopy using synchrotron radiation greatly expands the utility of chiroptical technique for the structural analysis of biomolecules by combining with theoretical analysis and bioinformatics. This spectroscopy provides the structural dynamics, intramolecular hydrogen bonds, and hydrations of saccharides, and also successfully estimates the secondary structure contents, numbers of segments, and sequences of native proteins and non-native proteins such as membrane-bound proteins. The circular dichroism theory of protein discloses the local structures of the amyloid fibrils at the molecular level. This synchrotron-radiation spectroscopy is opening a new filed in the glycobiology and structural biology.