SPring-8, the large synchrotron radiation facility

Release Date

07 Apr, 2014

RIKEN
Osaka University

Key Points
• Verification of the helix chirality of electric quadrupole orientations
• Observation of the spatial distribution of right- and left-handed structures coexisting in the helical electric quadrupoles
• Progress to the development of novel optical materials

《Glossary》
*1　Electric quadrupole
A type of electron orbit state. A dipole is a pair of positive and negative charge distributions separated by a distance in space. A compass is a simple example of a magnetic dipole. On the other hand, a quadrupole is a set of four charge distributions, two are positive and two are negative, which are combined in space.

*2　Enantiomerphic structure and enantiomer
A pair of substances whose crystal or molecular structures have the same relation as human hands. For example, our right and left hands are not superposable no matter how we rotate or move them unless they are reflected in a mirror. The right- and left-handed structures have the same physical properties but the plane of polarization of light transmitted through these structures rotates in opposite directions; that is why they are called enantiomers or optical isomers. All amino acids that constitute our body are left-handed. Enantiomers are known to show optical rotation, a property where the plane of polarization of transmitted light rotates in opposite directions, but the structures of enantiomer pairs are distinguished from each other.

*3　3d transition metal compounds
Compounds containing elements from scandium (Sc), atomic number 21, to copper (Cu), atomic number 29. Because of their various chemical binding forms, magnetic structures, and orbital states, these compounds have been utilized in research on a wide variety of functional materials such as high-temperature superconductors.

*4　4f rare-earth metal compounds
Compounds containing elements from lanthanum (La), atomic number 57, to lutetium (Lu), atomic number 71. They are used in various industrial products such as permanent magnets, liquid crystals, and catalysts.

*5　Resonant X-ray diffraction
A diffraction method using synchrotron radiation X-rays. Information about the symmetry, direction, and relative size of a specific electron orbit of an atom can be obtained by irradiating a sample with X-rays with an energy that equals the atom-specific resonant state.

*6　Large synchrotron radiation facility, SPring-8
A facility that generates the world’s highest-performance synchrotron radiation. It is located in Harima Science Garden City in Hyogo prefecture and is owned by RIKEN. Japan Synchrotron Radiation Research Institute (JASRI) is responsible for its operation, management, and support of users. The name SPring-8 is derived from Super Photon ring-8 GeV. Synchrotron radiation refers to the strong electromagnetic waves generated when the orbit of electrons, accelerated to a near-light speed, is bent by magnetic field. Research on various fields from fundamental science and industrial applications is conducted at SPring-8.

*7　Circularly polarized
Light and X-rays are transverse waves in which electric and magnetic fields travel while oscillating. Circularly polarized light refers to the light whose electric field rotates around the axis of propagation of the light while electric and magnetic fields travel a distance of one period. Right circularly polarized light is the light whose electric field rotates counterclockwise with time for an observer who looks at the light in the direction of the light source. The spatial trajectory of right circularly polarized light resembles a left-handed screw when viewed from both directions.