We investigated the magnetic excitations and lattice vibrations in a spinel-type vanadium oxide MnV2O4 by using inelastic neutron and x-ray scattering. We discovered magnetic excitations which were not reproduced by the linear spin-wave calculation. We also confirmed that the excitation modes were not explained by the simple lattice vibration, since the dispersion and the scattering intensity are different from those obtained from inelastic neutron scattering experiment. Therefore, we proposed that the observed excitation was related to the orbital excitation mode coupling with the spin-wave excitation via spin-orbital exchange interaction and the relativistic spin-orbit interaction.
Since the appearance of bulk heterostructures, organic thin film solar cells have attracted attention as next-generation energy sources. Earlier studies have addressed quantum chemical calculation in an excited state and a ground state of phthalocyanine–fullerene bimolecular systems. Phthalocyanines and fullerenes are well known as materials of organic thin film solar cells. Based on these reports, we have devised a new method of manufacturing organic thin film solar cells and have prepared a device incorporating those features. Nevertheless, the device is so soft that it is considered necessary to strengthen the device by incorporating a fibrous substance. This study investigated the effects on its electronic properties of incorporating molecules like nylon 6 into phthalocyanine using quantum chemical calculation. Results demonstrate partial defects in the electron cloud of phthalocyanine molecules, revealing the occurrence of positive holes. These electron cloud defects result from interaction between nylon dimer molecules and phthalocyanine molecules.
Recently, renewable energy is attracting attention globally. In Japan today, there is a shift with growing momentum to photovoltaic power generation from thermal power generation, which has heretofore served as the foundation of electrical power generation. We are studying improvement of the photovoltaic conversion efficiency of bulk heterojunction organic thin film solar cells and are preparing a device that requires detailed elucidation of its electronic properties and its mechanism of power generation. Accordingly, we have conducted quantum chemical calculations using a molecular pair of phthalocyanine and fullerene C60 employed as a specimen. Specifically, we have computed charge densities and electron clouds in the ground state while varying the molecular distance to 12 Å and 24 Å using the density functional method. Results demonstrate quite high negative charge density in C atoms near phthalocyanine in C60 when the distance between the two molecules is decreased to 12 Å, with a positive charge density in C atoms on the opposite side of phthalocyanine in C60. Results suggest that many conduction electrons and positive holes, the so-called carriers, are generated in the phthalocyanine − fullerene C60 bimolecular system when the molecular distance is decreased to 12 Å.
Electron cloud effect has been studied for J–PARC RCS (Rapid Cycling Synchrotron) and MR (Main Ring). Numerical simulation shows electron cloud may build-up to the neutralization level of a few %. With a linear theory and numerical simulation, electron-proton (e–p) instability is examined. Electron cloud observation at the KEK–PS is also discussed for comparison. The present investigation shows that e–p instability in the J–PARC rings will be manageable, assuming some remedies such as local solenoid magnets.
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