Hideo Onuki

Absolute spectral brightness and polarization characteristics of radiation from a polarizing undulator in the visible region

A polarizing undulator has been constructed utilizing crossed and retarded magnetic fields that can provide arbitrary polarized radiation. The absolute brightness and polarization characteristics have been studied in the visible region from 350–700 nm at 230 MeV of stored electron energy by varying the observation angle θ. Any desired elliptically polarized radiation was obtainable by adjusting the retardation between the two pairs of magnet arrays.

Polarization modulation spectroscopy for magnetic circular dichroism study using a polarizing undulator

We developed a polarization modulation spectroscopy in the extreme ultraviolet (XUV) region for magnetic circular dichroism (MCD) measurements. We used a polarizing undulator with crossed and retarded magnetic fields. It enables us to obtain radiation adjusting the polarization states arbitrarily and rapidly. The undulator is essential in our polarization modulation spectroscopy for MCD study in the XUV region.

First absolute asymmetric synthesis with circularly polarized synchrotron radiation in the vacuum ultraviolet region: direct photoderacemization of (E)-cyclooctene

A newly developed polarizing undulator installed in a storage ring was employed for the first time as a source of circularly polarized synchrotron radiation in the vacuum ultraviolet to effect enantiodifferentiating direct photoisomerization of (E)-cyclooctene; the photolysis is taken as a terrestrial mimic or proof of extraterrestrial absolute asymmetric synthesis on interstellar grains by the polarized synchrotron radiation from fast electrons orbiting a neutron star, which is thought to be a distant origin of the homochirality in the biosphere.

COMPUTER SIMULATION STUDY OF UNDULATOR RADIATION

Calculations of the radiation from a four‐period polarizing undulator by use of the general radiation equation and numerical integration including the effects of electron‐beam emittance, energy spread, and finite observation distance are presented. Accurate electron‐beam profiles have been experimentally determined and modeled by the Monte Carlo method. Good agreement is found in spectral intensity between the measured and calculated spectra.

Observation of Strong Magnetic Circular Dichroism of `Nonmagnetic' Y3+ Core Transition in Ferrimagnetic YIG Lattice

Magnetic circular dichroism (MCD) of Y 3 Fe 5 O 12 (YIG) was measured in the vacuum ultraviolet region between 22 eV and 40 eV by use of a polarizing undulator with crossed and retarded magnetic fields. Strong MCD features were observed for the inner core transitions of Y 3+ from the 4 p 6 to 4 p 5 (4 d +5 s ) levels, even though its ground state has J =0. It is suggested that the `nonmagnetic Y 3+ ion in a ferrimagnetic YIG lattice has an induced magnetic moment on the order of 0.01 µ B /ion.

APPLICATION OF OBLIQUE INCIDENCE DETECTOR TO VACUUM ULTRAVIOLET POLARIZATION ANALYZER

Use of a photodetector placed obliquely to the incident radiation was proposed as a simple polarization analyzer in the vacuum ultraviolet. An ellipsometer using a Au‐GaAsP photodiode as an analyzer of this method was constructed and was shown to work successfully. The polarization characteristics obtained in this experiment agreed well with a model calculation.

Development of a circularly polarizing microscope with a polarizing undulator

A circularly polarizing microscope by which we intend to obtain images with CD (circular dichroism) or CIDS (circular intensity differential scattering) in order to observe the structure and distribution of biomolecules has been constructed by using a polarizing undulator as the polarizing light source. The polarizing undulator with crossed and retarded magnetic field having fifteen periods was installed in the electron storage ring NIJI‐II in the Electrotechnical Laboratory. A Schwarzschild‐type mirror system combined with a convex mirror was developed in order to focus the undulator radiation to a microbeam keeping the quality of polarization of the radiation from the undulator. The beam size was from 0.66 μm (at wavelength 200 nm) to 0.96 μm (at 400 nm). Using a scanning sample stage and a photomultiplier which was positioned in the back of the sample, some images with transmitted and scattered light from fibrous DNA have been obtained. Attempts have also been made at obtaining images with CD and CIDS ...