ISSP - The institute for Solid State Physics

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Harada Group
Professor
HARADA,
Yoshihisa

Research Associate
MIYAWAKI,
Jun

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We explore the origin of the electronic structure of materials responsible for their electronic, magnetic and optical properties using intense and energy tunable X-ray source: SPring-8, one of the most brilliant synchrotron facilities in the world. We have developed novel spectroscopies for material science in ‘soft’ X-ray region. We are leading the world’s soft X-ray emission spectroscopy, a kind of light scattering promising for electronic structure analyses of liquids and operando spectroscopy of a variety of catalysts. Our topics include study on elementary excitations (crystal field excitation, spinon, magnon, charge density wave, orbiton etc.) in strongly correlated materials like Mott insulators and novel high Tc superconductors, electronic structure analysis of aqueous solutions, interaction at solid-liquid interfaces, surface reaction of fuel cell catalysts, electronic structure analysis of reaction center in metalloproteins, electrochemical and photocatalytic reactions. We also explore basic study on high performance soft X-ray emission spectroscopy for the next generation synchrotron light source.

High energy resolution soft X-ray angle resolved emission spectrometer constructed for University of Tokyo outstation beamline BL07LSU in SPring-8.
Electronic structure of H2O water in a polymer electrolyte brush observed by high energy resolution soft X-ray emission spectrometer. The X-ray emission profile is similar to crystalline ice Ih except for the 3a1 derived state, indicating an ordered but uniformly distorted hydrogen bond network of water in the brush like ice even at room temperature. The distortion is induced by a local electric field present in the polymer brush.

Research Subjects

  1. Electronic structure analysis of aqueous solutions to study microheterogeneity and interaction at solid-liquid interfaces
  2. Development of in situ soft X-ray spectroscopy for surface reaction of fuel cell catalysts, electrochemical reaction, photocatalytic reaction and functionality of metalloproteins
  3. Study on the origin and observation of elementary excitations (crystal field excitation, spinon, magnon, charge density wave, orbiton etc.) in strongly correlated materials like Mott insulators and novel high temperature superconductors.
  4. Basic study on ultrahigh energy resolution optics for soft X-ray emission and time-resolved spectroscopy