Takenori Tanno

Terahertz spectra of 1-cyanoadamantane in the orientationally ordered and disordered phases

We report the characteristic terahertz spectra of a plastic crystal and the alterations caused by phase transitions. The low-frequency vibrational modes of 1-cyanoadamantane in orientationally ordered and disordered (plastic) phases were investigated with a terahertz spectrometer. The frequencies of the intramolecular vibrational modes were in good agreement with theoretical calculations. The librational mode, which was directly observed for the first time, appeared at a lower frequency for the plastic phase.

Identification of textile fiber by terahertz spectroscopy

We developed a novel differentiation technique for most textile fibers using terahertz (THz) transmittance spectroscopy. As demonstrations, several kinds of plant-derived fibers, animal fibers, and artificial fibers were milled at 77K, and were examined by THz spectroscopy in the range from 0.5 to 6.2 THz. Absorption spectra of a majority of textile fibers are distinguishable by THz spectroscopy, even for fibers in the same category or species. The advantage of this technique is its sensitivity to the structural differences of the textile fibers, even if they consist largely of the same components.

Significance of terahertz spectrometry for textile article of wool

We present a novel differentiation technique for several kinds of textile fabric using terahertz (THz) transmittance spectroscopy. Our goal is to establish a new method for identification of each of wools from their animal species, as a simple, rapid and reliable method to confront fake textile problem in the market. As demonstrations, several kinds of fabrics were milled at 77K, and were examined by using GaP THz spectrometer in the measurement range from 0.5 to 6.0 THz. The absorption spectra of wool showed quite different spectra from plant-derived fibers and synthetic fibers. Furthermore, the spectra of pure wools showed different transmittance spectra between goat-wool and sheep-wool, in addition among the species of sheep.

Pump–probe scanning-tunneling-microscope light-emission spectroscopy of Sb2Te3

We have investigated the temporal behavior of Sb2Te3 after irradiation with picosecond (ps) pump-laser pulses using scanning-tunneling-microscope (STM) light emission synchronized with ps-probe-laser pulses delayed by times t after individual pump pulses. We determined the gap energy Δ E at the F point in the band diagram of Sb2Te3 from the STM light-emission spectra as a function of the delay time t. We found that Δ E increased monotonically with t from the original value of 1.62 eV for a delay time of 0 to 15.3 ps and it decreased toward that original value (1.62 eV) for t in the time span between 15.3 and 28 ps; we saw no change in Δ E for t ≥ 28 ps. By comparing this t-dependence of Δ E with the dielectric functions of the crystalline and amorphous phases of Sb2Te3, we have concluded that the phase transition from the crystalline phase toward the amorphous phase is induced by the pump pulses. The phonon energy of the A2u mode is clearly seen in the STM light-emission spectra when Δ E is 1.62 eV, but not when Δ E is increased above 1.62 eV by pump-pulse irradiation. This feature appears to be consistent with the Raman signals, which are much stronger for the crystalline phase than for the amorphous phase.We have investigated the temporal behavior of Sb2Te3 after irradiation with picosecond (ps) pump-laser pulses using scanning-tunneling-microscope (STM) light emission synchronized with ps-probe-laser pulses delayed by times t after individual pump pulses. We determined the gap energy Δ E at the F point in the band diagram of Sb2Te3 from the STM light-emission spectra as a function of the delay time t. We found that Δ E increased monotonically with t from the original value of 1.62 eV for a delay time of 0 to 15.3 ps and it decreased toward that original value (1.62 eV) for t in the time span between 15.3 and 28 ps; we saw no change in Δ E for t ≥ 28 ps. By comparing this t-dependence of Δ E with the dielectric functions of the crystalline and amorphous phases of Sb2Te3, we have concluded that the phase transition from the crystalline phase toward the amorphous phase is induced by the pump pulses. The phonon energy of the A2u mode is clearly seen in the STM light-emission spectra when Δ...

Ligand Exchange Reactions of a Monomeric Zirconium Carbonate Complex with Carboxylic Acids Studied by Extended X-ray Absorption Fine Structure, UV Absorption and Raman Spectrophotometry

Ligand exchange reactions of a monomeric zirconium carbonate complex with carboxylic acids were studied by means of extended X-ray absorption fine structure (EXAFS), UV absorption spectrophotometry and Raman spectrometry. Three carboxylic acids, gluconic acid, and L-tartaric acid and citric acid, which are mono-, di- and tri-carboxylic acids, respectively, were employed in this study. These three carboxylic acids gave different spectral signatures and concentration dependences, respectively. In the gluconic acid system, the peaks on Fourier transform of EXAFS spectrum and Raman spectrum caused by carbonate ion coordinating to zirconium atom were obviously decreased with increasing gluconic acid concentration compared to the other two carboxylic acid systems. This indicates the high association ability of gluconic acid to zirconium, which was revealed by UV spectrophotometric analysis.

Synthesis of Large Porous Particles of Iron Oxide and Their Arsenic Adsorption Characteristics in Aqueous Solution

A novel method has been developed for the synthesis of large porous particles of iron oxide. In this synthesis, large particles of phosphosiderite (FePO4 2H2O)were first prepared by coprecipitation from an Fe(II) and P(V) aqueous solution by oxygen injection at about 368 K. Porous particles of iron oxide were then obtained by removing the phosphorus in the particles in an alkaline solution. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize formation of the porous particles of iron oxide. The extended X-ray absorption fine structure (EXAFS) in the range of the Fe K absorption edge was investigated to characterize the local structure of the porous particles. The characteristics of As adsorption onto the porous particles of iron oxide were examined by analyzing the As concentration in aqueous solution. For comparison, the As adsorption characteristics of -Fe2O3 particles, which were prepared from -FeOOH, were also studied. The results showed that the porous particles of iron oxide prepared from large phosphosiderite particles had superior As adsorption characteristics compared to those of -Fe2O3 particles prepared from -FeOOH. It was shown that large porous particles of iron oxide with high filterability in water are promising for use as As adsorbents in aqueous solution.

Accurate modeling of inter- and intra-molecular interactions in 1,4-dihydroxynaphthalene in the 0.5-6 terahertz region

Semi-empirical calculations successfully predicted the terahertz (THz) absorption spectrum associated with intra- and intermolecular interactions in 1,4-dihydroxynaphthalene. Results are in excellent agreement with spectroscopy data in the 0.5-6 THz region using GaP wave THz source.

Numerical calculations of the Frequency Spectra of naphthalene and 1,4-dihydroxynaphthalene in the 0.5-to 6 terahertz region

Semi-empirical calculations successfully predicted the terahertz (THz) absorption spectrum associated with intra- and intermolecular interactions in 1,4-dihydroxynaphthalene. Results are in excellent agreement with actual spectroscopy data in the 0.5-6 THz region using GaP THz source.

Terahertz transmission spectroscopic analysis of mono- and di-substituted hydroxynaphthalenes in the 0.5- to 6- THz region using GaP THz wave generator

We report the room temperature terahaertz (THz) transmission spectroscopy measurements of mono-and di-substituted hydroxynaphthalenes in the 0.5-to 6-THz region using a GaP THz wave generator. Several absorption peaks were observed and ascribed to be the fundamental vibrational modes of each of the isomers which were also validated by ab initio calculations. The absorption peak at 4 THz is attributed to the twisting of the 1,4-naphthol about its longer axis while the absorption peak at 5 THz is due to the butterfly motion of the naphthol about its shorter axis.