Phase control of iron silicides using femtosecond laser irradiation

Phase control of Fe–Si amorphous thin film in micro area is demonstrated using femtosecond laser irradiation. A femtosecond laser beam with a high repetition rate over 200 kHz and tightly focused through an objective lens promotes both crystallization and phase transformation from an amorphous phase into crystalline β-FeSi₂, α-FeSi₂, or ε-FeSi phases. Formation of each crystalline phase is possible by changing the pulse energy or the scanning speed of the incident laser beam.     

Visible-super-resolution infrared microscopy using saturated transient fluorescence detected infrared spectroscopy

A scanning visible-super-resolution microscope based on the saturation behaviour of transient fluorescence detected infrared (TFD-IR) spectroscopy is proposed. A Gaussian IR beam, a Gaussian visible beam and a Laguerre-Gaussian (LG) visible beam are used to obtain two separate two-color excitation fluorescence (2CF) images of the sample. The final image is obtained as the difference between the two recorded images. If the peak intensity of the LG beam is high enough to induce saturation in the fluorescence signal, the image can, in principle, have unlimited spatial resolution. A ∼3-fold improvement in transverse resolution over the visible diffraction limit (and far exceeding the IR diffraction limit) is easily achievable in present experimental setups.     

Highly efficient 1181 nm output from a transversely diode-pumped Nd:KGd(WO4)2 self-stimulating Raman laser

We have achieved high average power Raman output from a compact, diode-pumped, self-stimulating Nd³⁺:KGd(WO₄)₂ Raman laser. Maximum Raman output power of 0.8 W was achieved at a pulse repetition frequency (PRF) of 2 kHz. The optical efficiency from diode to Raman laser was 14%. By generating extra-cavity second harmonics using a LiB₃O₅ crystal, it was possible to produce 0.2 W yellow output. The laser system was simulated numerically using rate equations and the results obtained were in good agreement with the experimental results.     

Preparation of micron-sized, monodispersed, “onion-like” multilayered poly(methyl methacrylate)/polysterene composite particles by reconstruction of morphology with the solvent-absorbing /releasing method

Micron-sized, monodispersed, “onion-like” multilayered poly(methyl methacrylate) (PMMA)/polystyrene (PS) (1/1, w/w) composite particles were prepared by the solvent-absorbing/releasing method (SARM). The viscosity within toluene-swollen composite particles, the release rate of toluene therefrom, the PMMA/PS ratio, and the kind of solvent had great influences on the reconstruction of the morphology of the PMMA/PS composite particles by the SARM. From these results, the conditions for the preparation of the multilayered composite particles by the SARM are clarified. Received: 28 September 2000 Accepted: 27 October 2000     

High Field ESR System and Its Application to the Study of Quantum Spin Systems

Developments of the high field ESR system in Kobe University is presented. Using Gunn oscillators and backward traveling oscillators (BWO), we can cover the frequency region from 30 to 1183.6 GHz with the use of InSb detector. Pulsed magnetic field up to 30 T is available and we are now trying to extend the field up to 40 T. Temperature range is from 1.8 to 300 K. Using this system, we studied S=1/2 ladder like system Cu₂(C₅H₁₂N₂)₂Cl₄, and found a new magnetic transition at 10.1 T at 1.8 K. The temperature dependence of ESR in Cu₂(C₅H₁₂N₂)₂CI₄ shows g-shift below 8 K which corresponds to the maximum of the magnetic susceptibility. The g-shift below 8 K suggests the increase of the quantum fluctuation in the system, and the role of the quantum fluctuation in Cu₂(C₅H₁₂N₂)₂CI₄ is discussed.     

Nondestructive analysis of silver in gold foil using synchrotron radiation X-ray fluorescence spectrometry.

Small particles of gold foil detached from an indoor decoration might be important evidence to associate a suspect with a crime scene. We have investigated the application of elemental analysis using synchrotron radiation X-ray fluorescence spectrometry to discriminate small particles of gold foil. Eight kinds of gold foil samples collected in Japan were used in the experiments. As a result of synchrotron radiation X-ray fluorescence spectrometry, only two elements, gold and silver, were detected from all gold foil samples. The intensity ratios of AgKalpha/AuLalpha showed good correlation with the content ratios of Ag/Au. The variation of intensity ratio within a same sample was sufficiently small compared with those of different samples. Therefore the comparison of this intensity ratio can be an effective method to discriminate small particles originating from different types of gold foil.     

Electrochemical immunoassay for vitellogenin based on sequential injection using antigen-immobilized magnetic microbeads.

A rapid and sensitive immunoassay for the determination of vitellogenin (Vg) is described. The method involves a sequential injection analysis (SIA) system equipped with an amperometric detector and a neodymium magnet. Magnetic beads, onto which an antigen (Vg) was immobilized, were used as a solid support in an immunoassay. The introduction, trapping and release of magnetic beads in an immunoreaction cell were controlled by means of the neodymium magnet and by adjusting the flow of the carrier solution. The immunoassay was based on an indirect competitive immunoreaction of an alkaline phosphatase (ALP) labeled anti-Vg monoclonal antibody between the fraction of Vg immobilized on the magnetic beads and Vg in the sample solution. The immobilization of Vg on the beads involved coupling an amino group moiety of Vg with the magnetic beads after activation of a carboxylate moiety on the surface of magnetic beads that had been coated with a polylactate film. The Vg-immobilized magnetic beads were introduced and trapped in the immunoreaction cell equipped with the neodymium magnet; a Vg sample solution containing an ALP labeled anti-Vg antibody at a constant concentration and a p-aminophenyl phosphate (PAPP) solution were sequentially introduced into the immunoreaction cell. The product of the enzyme reaction of PAPP with ALP on the antibody, paminophenol, was transported to an amperometric detector, the applied voltage of which was set at +0.2 V vs. an Ag/AgCl reference electrode. A sigmoid calibration curve was obtained when the logarithm of the concentration of Vg was plotted against the peak current of the amperometric detector using various concentrations of standard Vg sample solutions (0-500 ppb). The time required for the analysis is less than 15 min.     

Forensic discrimination of sheet glass by a refractive-index measurement and elemental analysis with synchrotron radiation X-ray fluorescence spectrometry.

Measurements of the refractive index (RI) and elemental analysis using synchrotron radiation X-ray fluorescence spectrometry (SR-XRF) were applied to the forensic discrimination of sheet-glass samples from different origins. The refractive index was calculated from the matching temperature at which the glass fragments became invisible in silicone oil. Fragments smaller than 1 mm in maximum diameter were taken from each of 11 sheet glasses and subjected to analysis by SR-XRF. The XRF spectrum of these samples indicated that a comparison of 6 elements (Ca, Fe, Sr, Zr, Ba and Ce) was useful for the discrimination of sheet glasses. Cluster analysis was performed using 33 sets of SR-XRF data obtained by triplicate measurements for the 11 glasses. Comparing 528 pairs among 33 samples, 515 pairs could be correctly discriminated. The number of indistinguishable pairs could be reduced from 36 to 4 by comparing the SR-XRF data. Elemental analysis by SR-XRF could provide small glass fragments with a more evidential value than the solely measurement of only RI, through a significant improvement of the discrimination capability.     

“Radical‐controlled” oxidative polymerization of phenol: Comparison with that of 4‐phenoxyphenol

“Radical‐controlled” oxidative polymerization of phenol (p‐1) by (1,4,7‐triisopropyl‐1,4,7‐triazacyclononane)copper(II) catalyst was performed and compared with that of 4‐phenoxyphenol (p‐2) in detail. Although the coupling selectivity for p‐1 seemed to be controlled by the catalyst, the C? C coupling, which was excluded completely for p‐2, occurred to some extent. The initial reaction rate of p‐1 was much smaller than that of p‐2, leading to the difference of polymerization behavior between p‐1 and p‐2. The rate‐determining step would be the coupling of controlled radicals species from the ESR measurement of the reaction mixture. The polymer resulting from p‐1 consisted mainly of phenylene oxide units, but had no crystallinity in contrast to the crystalline polymer from p‐2. However, the present polymer showed the highest thermal stability in the polymers obtained by oxidative polymerization of p‐1. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1955–1962, 2005