Ultrafast electron dynamics of solids after an absorption of femtosecond laser pulse is governed by electron-electron, electron-phonon, and phonon-phonon collisions. It is of importance to construct a framework for interpreting experimental observations correctly. In this paper we review recent developments of modeling the relaxation dynamics of solids. We discuss the ultrafast relaxation in respect to the effective temperature dynamics and the excess energy dynamics.
CaVO3 (CVO)-based all-solid-state redox transistor with a Yttria-stabilized-ZrO2 (YSZ) H+ ion conductor was fabricated. The electronic conductivity of the CVO was modulated by controlling oxygen nonstoichiometry due to H+ insertion and desertion (redox reaction). The variation in drain current was larger than that of SrVO3 (SVO)-based all-solid-state redox transistor. For comparison, the CVO-based device with a Li2O-ZrO2-SiO2 (LZSO) Li+ conductor was also investigated. The LZSO device also showed larger drain current enhancement than the SVO device. Controlling oxygen nonstoichiometry due to the redox reaction (H+ or Li+ insertion and desertion) is found to be effective for modulating electronic conductivity of CVO.
We performed three-dimensional observation of simulated fuel debris by combining synchrotron computed tomography (CT) and high-energy X-ray diffraction. The goal of this study is clarifying what kind of compound does fuel debris consist of, and by what kind of environment was fuel debris generated? To solve these problems, we tried structural analysis and morphology observation using simulated fuel debris. CT was used to make the inside of simulated fuel debris clear. The inner structure of simulated fuel debris gives us the important information which environment simulated fuel debris were formed. The observed CT image provides that a clear contrast in the zirconia-rich and concrete-rich parts. From the molten state, zirconia is first precipitated. Zirconia moves to the lower part when crystals precipitated and aggregated near the bottom surface. Phase separation caused by the difference in the composition of zirconia, and can also be observed the difference in the crystal growth mode depending on the zirconia composition.
Using an alcohol gas source chemical vapor deposition method, we attempted to grow single-walled carbon nanotube (SWCNT) growth using Co catalysts on Al2O3 buffer layers. Reducing the growth temperature decreased the optimal ethanol pressure to obtain the highest SWCNT yield. By optimizing the ethanol pressure, we succeeded in growing SWCNTs at 400ºC. Irrespective of the growth temperature, SWCNT yields from Co catalysts on Al2O3 buffer layers were higher than those on SiO2/Si substrates, but the enhancing effects of Al2O3 buffer layers on SWCNT yield were reduced below 500ºC. Taking into account both in-plane X-ray diffraction results and decrease of catalyst aggregation in the low temperature region, we concluded that the density of Co particles suitable for SWCNT growth increased on SiO2 surface at low temperature, resulting in the reduction of difference in SWCNT yield at low temperature between Al2O3 buffer layers and SiO2/Si substrates.
The compound (5-(3,5-dimethyl)pyrrol-2-yl)-3-(4-(dimethylamino)styryl)-1,7-dimethyl benzo-fused BODIPY (BFBODIPY-DMP-DMAS) was synthesized and investigated as a fluorescent chemosensor for metal ions. We explored the metal-ion recognition of BFBODIPY-DMP-DMAS in separate acetonitrile solutions of Mg2+, Ca2+, Ba2+, Fe2+, Fe3+, Co2+, Ni2+, Cu2+, Ag+, Zn2+, Cd2+, Al3+, and Pb2+. Mg2+, Ca2+, Ba2+, Fe2+, Co2+, Ni2+, Ag+, Zn2+, Cd2+, and Pb2+ did not affect the shape or intensity of the fluorescence spectra of the chemosensor. However, the sensor fluorescence was shifted to shorter wavelengths for Al3+ and quenched for Fe3+ and Cu2+.
We simulated La Lγ1 X-ray fluorescence holography (La Lγ1 XFH) on a spherical cluster model of Sr0.95La0.05TiO3. As the radius of the model rc increased from 10 Å to 200 Å, the simulated hologram pattern became finer and sharper. The X-ray standing wave lines in the simulated hologram of the model with rc = 200 Å reproduced those in the experimentally obtained hologram well. Because the X-ray fluorescence hologram is defined as a function on a spherical surface, we estimate the fineness of the pattern by calculating the power spectrum with the spherical harmonics transform. The power spectrum of the holographic oscillations of the experimentally obtained hologram shows no cutoff below the Nyquist frequency. The power spectra of the models with 60 Å ≤ rc ≤ 200 Å do not show cutoffs either. These indicate that the radius of the cluster model rc should be set at least 200 Å to reproduce the experimentally obtained hologram of Sr0.95La0.05TiO3.