Yoshisuke Futami

Advances in Molecular Structure and Interaction Studies Using Near-Infrared Spectroscopy.

Infrared Spectroscopy Mirosław Antoni Czarnecki,*,† Yusuke Morisawa,‡ Yoshisuke Futami, and Yukihiro Ozaki* †Faculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław, Poland ‡Department of Chemistry, School of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan Department of Biological and Chemical Systems Engineering, National Institute of Technology, Kumamoto College, Yatsushiro, Kumamoto 866-8501, Japan Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan

Scintillation Properties of Transparent Ceramic Pr:LuAG for Different Pr Concentration

We manufactured transparent optical ceramic of Pr 0.2-1% doped Lu3Al5 O12 (Pr:LuAG) by the sintering method. We compare its optical and scintillation properties with the single crystal counterpart grown by the conventional Czochralski method. So far the scintillation ceramic of Pr:LuAG appeared inferior to its single crystal analog especially in terms of light yield. However, in the present case our ceramic Pr 0.25%-doped sample exhibited by 20% higher light yield compared to single crystal under γ-ray excitation. Furthermore, in the ceramic sample the slower scintillation decay components were suppressed and the defect related host emission as well. The optimized technology of optical ceramics thus appears very competitive to single crystals and opens great practical prospectives for the former materials in the field of fast scintillators.

Fast and High-Energy-Resolution Oxide Scintillator: Ce-Doped (La,Gd)2Si2O7

A novel scintillation crystal (Ce0.01,Gd0.90,La0.09)2Si2O7 (Ce:La-GPS) was grown by the floating zone method, and its optical and scintillation properties were investigated. The emission wavelength of this material was 390 nm. Gamma ray excited pulse height and scintillation decay measurement showed that Ce:La-GPS had a high energy resolution (FWHM) of 5% at 662 keV, high light output of 36,000 photons/MeV and fast scintillation decay time of 46 ns.

Solvent dependence of absorption intensities and wavenumbers of the fundamental and first overtone of NH stretching vibration of pyrrole studied by near-infrared/infrared spectroscopy and DFT calculations.

Near-infrared (NIR) and IR spectra were measured for pyrrole in CCl(4), CHCl(3), and CH(2)Cl(2) to study solvent dependence of absorption intensities and wavenumbers of the fundamental and first overtone of NH stretching vibration. It was found that the wavenumbers of the NH fundamental and its first overtone decrease in the order of CCl(4), CHCl(3), and CH(2)Cl(2), which is the increasing order for of the dielectric constant of the solvents. Their absorption intensities increase in the same order, and the intensity increase is more significant for the fundamental than the overtone. These results for the solvent dependence of the wavenumbers and absorption intensities of NH stretching bands of pyrrole are quite different from those due to the formation of hydrogen bonds. Quantum chemical calculations of the wavenumbers and absorption intensities of NH stretching bands by using the 1D Schrödinger equation based on the self-consistent reaction field (SCRF)/isodensity surface polarized continuum model (IPCM) suggest that the decreases in the wavenumbers of both the fundamental and the overtone of the NH stretching mode with the increase in the dielectric constant of the solvents arise from the anharmonicity of vibrational potential and their intensity increases come from the gradual increase in the slope of the dipole moment function.

Ultrafast Transparent Ceramic Scintillators Using the Yb3+ Charge Transfer Luminescence in RE2O3 Host

We report a new discovery of Yb3+-doped ultrafast scintillators based on the Yb3+ charge transfer luminescence. Transparent ceramic Yb3+-doped Y2O3, Sc2O3, Lu2O3, and Yb2O3 were prepared by sintering. When irradiated by γ- and X-rays, they showed a well detectable photoabsorption peak in the pulse height spectra and ultrafast scintillation decay dominated by the decay time of about 1 ns. For the first time, the Yb3+-doped oxide materials show detectable scintillation in the pulse height measurement at room temperature with ultrafast scintillation decay.

Combined IR/NIR and Density Functional Theory Calculations Analysis of the Solvent Effects on Frequencies and Intensities of the Fundamental and Overtones of the C=O Stretching Vibrations of Acetone and 2-Hexanone

Vibrational overtone studies primarily focus on X-H stretching overtone transitions, where X is an atom like C, O, N, or S. In contrast, the studies on the C ═ O stretching overtones are very scattered. To advance the research in this field, we measured the fundamental, first, and second overtones of the C ═ O stretching vibration of acetone and 2-hexanone in n-hexane, CCl4, and CHCl3, as well as in the vapor phase using FT-IR/FT-NIR spectroscopy. Density functional theory (DFT) calculations have also been performed to help the assignment of the C ═ O stretching bands and to guide interpretation of the experimental results. It was found that the wavenumbers, absorption intensities, and oscillator strengths of the C ═ O stretching bands show marked solvent dependence. In the fundamental and the first overtone regions, the intensities of the C ═ O stretching vibration were found to be pronouncedly more intense than those of the C-H stretching vibration. In the second overtone region, the intensities of the C-H stretching vibration are comparable to those of the C ═ O stretching vibration. The theoretical and observed decrease in integrated intensity upon going from the fundamental to the first overtone of the C ═ O stretching vibration is around 50, which is significantly larger than those of the O-H, C-H, and S-H stretching vibration. Both the calculated and experimental results suggest that excessive weakness in the C ═ O stretching overtone was shown to be a result of both a low anharmonicity and a substantial reduction in the oscillator strength. These results provide new insight into our understanding of the C ═ O stretching vibration.

Spectroscopic and Computational Study of Acetic Acid and Its Cyclic Dimer in the Near-Infrared Region

Anharmonic vibrational analysis of near-infrared (NIR) spectra of acetic acid was carried out by anharmonic quantum chemical calculation in a wide concentration range of its CCl4 solution. By predicting vibrational spectra of acetic acid for the first time over a wide NIR region, it was possible to elucidate the influence of the formation of acetic acid cyclic dimer on its NIR spectrum. Quantum chemical simulations were based on coupled cluster and density functional theory quantum methods. Additionally, Møller-Plesset perturbation theory was employed for the additional calculation of hydrogen bonding stabilization energies. An anharmonic vibrational analysis was performed with the use of generalized second-order vibrational perturbation theory (GVPT2). A hybrid approach was assumed, in which monomeric species was treated by CCSD(T)/aug-cc-pVDZ (harmonic approximation) and B3LYP/SNSD (anharmonic approximation) methods. For the cyclic dimer, B3LYP and B2PLYP single and double hybrid functionals, paired with an SNSD basis set, were employed. DFT calculations were augmented with additional empirical dispersion correction. It was found that quantum chemically calculated vibrational modes in the NIR region are in a good agreement with experimental data. The results of anharmonic vibrational analysis were supported by a harmonic shift analysis, for elucidating the very strong anharmonic coupling observed between stretching modes of hydrogen bonded bridge in the cyclic dimer. However, the calculated wavenumbers for combination modes of double hydrogen bonded bridge in the cyclic dimer, which are very sensitive to the formation of hydrogen bonding, were found to be underestimated by quantum chemical methods. Therefore, by band fitting, the wavenumbers and shape parameters for these bands were found, and the modeled spectra were adjusted accordingly. A high accuracy of simulated spectra was achieved, and a detailed analysis of the experimental NIR spectra of acetic acid was possible, with successful identification of numerous experimental bands, including those which originate from concentration effects. It was also found that the main spectral features observed in the NIR spectra of carboxylic acid upon the formation of hydrogen bond should be accounted for combination modes of the stretching and bending vibrations of double hydrogen-bonded bridge in the cyclic dimers of acetic acid.

Shaped crystal growth of langasite-type piezoelectric single crystals and their physical properties

We have grown shape-controlled langasite-type crystals by the micro-pulling-down (μ-PD) method. Columnar shaped La₃Ta_0.5Ga_5.5O₁₄ (LTG), Ca₃NbGa₃Si₂O₁₄ (CNGS), Ca₃TaGa₃Si₂O₁₄ (CTGS), Sr₃NbGa₃Si₂O₁₄ (SNGS), and Sr₃TaGa₃Si₂O₁₄ (STGS) crystals were grown using a Pt-Rh crucible with a 3-mm-diameter columnar die at the bottom. All grown crystals showed high transparency except for the peripheral area and diameter of approximately 3 mm. The chemical phases at the central parts of the grown crystals were identified as a single phase of langasite-type structure and their lattice parameters were almost the same as those of crystals grown by the Czochralski (Cz) method; however, some impurity phases were observed in the peripheral area. In X-ray rocking curve measurements, the grown crystals indicated equivalent crystallinity to the crystal grown by the Cz method. The piezoelectric constant d₁₁ of the CNGS crystal was 3.98 pC/N; this value is well correlated with those of previous reports.

Fluorescence and radiation response properties of Ce3+-doped CaO–Al2O3–B2O3 glass

Basic fluorescence and radiation response properties of 7.5CeO2–22.5CaO–20Al2O3–50B2O3 (in molar percent) glass were evaluated. The Ce-doped glass was prepared according to a conventional melt quenching method using a Pt crucible in air atmosphere. The photoluminescence (PL), thermoluminescence (TL), and optically stimulated luminescence (OSL) spectra showed a blue emission band due to the 5d–4f allowed transition of Ce3+. The fluorescence quantum efficiency and decay time of Ce3+ were estimated to be about 60% and 37 ns, respectively. The glass exhibited good linear TL and OSL responses in 1–1000 and 30–3000 mGy dose ranges, respectively.

Nd3+ Doped LiCaAIF6 Single Crystal for Scintillator Application

ααΑαNd3+ 0.5% Doped Single Crystal LiCaAlF6 Scintillator Was Grown by the Micro-Pulling down (µ-PD) Method. Powder X-Ray Diffraction Analysis Was Done and the Grown Crystal Was a Single Phase LiCaAlF6. it Was Cut and Polished to the Physical Dimension of 1 × 2 × 7 mm3. in Transmittance Spectrum, Nd3+ 5d-4f Absorption Observed at 175 Nm and the Transmittance Became 80% at Wavelength Longer than 180 Nm. Excited by 160 Nm, Nd3+ 5d-4f Emission Appeared at 180 Nm. X-Ray Induced Radio-Luminescence Spectrum Showed the Similar Feature with the Photoluminescence One. when Coupled with PMT and Irradiated by 241Am α-Ray, the Absolute Light Yield Resulted 100 Ph/5.5 Mev α.