Keiichi Osaka

Prominent Electron Transport Property Observed for Triply Fused Metalloporphyrin Dimer: Directed Columnar Liquid Crystalline Assembly by Amphiphilic Molecular Design

A triply fused copper porphyrin dimer, when site-specifically modified on its periphery with hydrophobic and hydrophilic wedges (1C12/TEG), self-assembles into a columnar liquid crystalline (LC) mesophase over a wide-temperature range from -17 to 99 degrees C but gives rise to an amorphous solid when modified with only hydrophobic (1C12/C12) or hydrophilic wedges (1TEG/TEG). A LC film of 1C12/TEG displays at 16 degrees C a top-class one-dimensional electron mobility (0.27 cm2/V x s), as evaluated from its maximum flash-photolysis time-resolved microwave conductivity.

Structural and Magnetic Properties of Spinel FeV2O4 with Two Ions Having Orbital Degrees of Freedom

Spinel FeV 2 O 4 with orbital degrees of freedom both at the Fe 2+ and V 3+ ions exhibits successive structural phase transitions. We studied this structural and magnetic properties as well as the correlation between the two. We found that the crystalline domains in the tetragonal or orthorhombic phases can be aligned by the applied magnetic field, inducing a large magnetostriction (∼1%). The competition and cooperation of Fe 2+ and V 3+ orbitals is the possible origin of these intriguing properties in FeV 2 O 4 .

Novel emission properties of melem caused by the heavy metal effect of lanthanides(III) in a LB film

A novel emissive molecular system is constructed by the intercalation of the fluorophore melem (triamino-tri-s-triazine) within a Langmuir-Blodgett (LB) film of stearic acid with the periodic arrangement of lanthanides (Ln(III)), mainly Pr(III) with supporting of Eu(III). From emission spectra, decay curves, quantum yields and XPS measurements, it is clarified that the external heavy metal effect of Pr(III) on melem is much stronger in the film than in the bulk solid state, resulting in producing an unusual triplet state of melem. The triplet state of melem in the LB film donates the excitation energy to Pr(III) in the LB film, which is completely different from the energy transfer pathway of Pr-melem complex in the solid state through the singlet state of melem.

Space-group symmetry for the perovskite Ca0.3Sr0.7TiO3

It is shown, using synchrotron x-ray powder diffraction at room temperature and above, by invoking geometrical and symmetry arguments, and most directly by electron diffraction, that the perovskite Ca0.3Sr0.7TiO3 at room temperature is tetragonal with space-group symmetry I4/mcm. This is in accord with the common view (Ball et al 1998 J. Solid State Chem. 139 238–47). The proposition that the compound adopts a metrically tetragonal orthorhombic structure in space group Imma (Ranjan and Pandey 1999 J. Phys.: Condens. Matter 11 2247–58) cannot be sustained.

A New Attachment of the Large Debye‐Scherrer Camera at BL02B2 of the SPring‐8 for Thin Film X‐ray Diffraction

We have developed a new attachment for thin film x‐ray measurements equipped with the large Debye‐Scherrer camera at BL02B2 of the SPring‐8. It is quite easy to handle and control the attachment using user‐friendly computer programs. It is also notable that the attachment realizes both low‐glancing‐angle incident beam condition and in‐plane measurement condition. The attachment enables us to measure high precision x‐ray diffraction data from many kinds of thin films with the Debye‐Scherrer camera. Using this attachment we try to analyze some dimensionally controlled thin film structures.