Biomedical subjects

Kazuo Furuya

Publications and source records attributed to Kazuo Furuya.

7 recordsLinked to original sources

PubMed2006

Second-harmonic spectroscopy of surface immobilized gold nanospheres above a gold surface supported by self-assembled monolayers.

We have investigated linear and nonlinear optical properties of surface immobilized gold nanospheres (SIGNs) above a gold surface with a gap distance of a few nanometers. The nanogap was supported by amine or merocyanine terminated self-assembled monolayers (SAMs) of alkanethiolates. A large second-harmonic generation (SHG) was observed from the SIGN systems at localized surface plasmon resonance condition. The maximum enhancement factor of SHG intensity was found to be 3 x 10(5) for the SIGN system of nanospheres 100 nm in diameter with a gap distance of 0.8 nm. The corresponding susceptibility was estimated to be chi((2))=750 pmV (1.8 x 10(-6) esu). In the SIGN system supported with the merocyanine terminated SAMs, the SHG response was also resonant to the merocyanine in the nanogap. It was found that the SHG response of the SIGN systems is strongly frequency dependent. This leads us to conclude that the large chi((2)) is caused by enhanced electric fields at the localized surface plasmon resonance condition and is not due to an increase of the surface susceptibility following from the presence of the gold nanospheres. The observed SHG was consistent with the theoretical calculations involving Fresnel correction factors, based on the quasistatic approximation.

Journal Article↗

PubMed2005

Growth of tungsten nanodendrites on SiO2 substrate using electron-beam-induced deposition.

Tungsten nanodendrite structures were fabricated on an insulator SiO2 substrate using an electron-beam-induced deposition process in a high voltage transmission electron microscope. The effect of electron beam accelerating voltage on the nanodendrite structures was investigated. The morphologies and their growth rates did not have obvious difference for the deposition at accelerating voltages from 400 to 1000 kV. A mechanism for the growth and morphology of the nanodendrite structure was proposed involving charge-up produced on the surface of the substrate, movement of charges to and accumulation at the convex surface of the substrate and the tips of the deposits. High-energy electron irradiation enhanced diffusion of W atoms in the nanodendrites, promoted crystallization of W grains, so that more crystallized W nanodendrite structures were achieved by the electron-beam-induced deposition process using higher energy electron beams.

Dendrites↗

PubMed2004

Direct UHV-TEM observation of palladium clusters on a silicon surface.

About 1 monolayer of palladium was deposited onto a silicon (111) 7 x 7 surface at a temperature of about 550 K inside an ultrahigh vacuum transmission electron microscope, resulting in formation of Pd2Si nanoislands and a 1 x 1 surface layer. Pd clusters created from an excess of Pd atoms on the 1 x 1 surface layer were directly observed by in situ plan view high-resolution transmission electron microscopy. When an objective aperture was introduced so that electron diffractions less than 0.20 nm were filtered out, the lattice structure of the 1 x 1 surface with 0.33 nm spacing and the Pd clusters with a trimer shape were visualized. It was found that image contrast of the 1 x 1 lattice on the specific height terraces disappeared, and thereby an atomic structure of the Pd clusters was clearly observed. The appearance and disappearance of the 1 x 1 lattice was explained by the effect of the kinematical diffraction. It was identified that a Pd cluster was composed of three Pd atoms without a centered Si atom, which is consistent with the model proposed previously. The feature of the Pd clusters stuck at the surface step was also described.

Microscopy, Electron↗

PubMed2004

Detection of iron-oxide layer on the surface of iron nitride using high-resolution electron microscopy and Fourier filtering.

High-resolution electron microscopy (HREM) was used to detect the surface Fe3O4 iron-oxide layer formed on [011] Fe4N iron nitride due to electron irradiation in the transmission electron microscope. The existence of a surface oxide layer was confirmed by both image processing and through-focus observation. Images of the iron oxide were revealed using the process of fast Fourier transformation (FFT) of experimental HREM images, filtering of the FFT patterns and inverse FFT. By through-focus observation, HREM images of iron oxide were obtained based on the tuning of contrast transfer function. Fourier filtering is effective for examining the beginning of phase transformation, because at this stage the diffraction spots of iron oxide are too weak to be detected. At the time when the iron oxide layer has developed to some extent, through-focus observation is useful to obtain an image of oxide layers.

Journal Article↗

PubMed2004

Electron microscopy observation of interface in diffusion-bonded copper joint.

The microstructure at the interface of diffusion-bonded joints of oxygen-free high-conductivity copper for two kinds of surface conditions, with and without argon ion bombardment treatment, was investigated using scanning and high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy. The results showed that argon ion bombardment effectively removed the surface oxide film layer and lowered the height of the surface asperity, so that inclusion formation was decreased and void shrinkage time was shortened at the interface of the bonded copper joints, and the tensile strength of diffusion-bonded copper joints was improved obviously.

Journal Article↗

PubMed2002

Ordering in a fluid inert gas confined by flat surfaces.

High-resolution transmission electron microscopy images of room-temperature fluid xenon in small faceted cavities in aluminum reveal the presence of three well-defined layers within the fluid at each facet. Such interfacial layering of simple liquids has been theoretically predicted, but observational evidence has been ambiguous. Molecular dynamics simulations indicate that the density variation induced by the layering will cause xenon, confined to an approximately cubic cavity of volume approximately 8 cubic nanometers, to condense into the body-centered cubic phase, differing from the face-centered cubic phase of both bulk solid xenon and solid xenon confined in somewhat larger (>/=20 cubic nanometer) tetradecahedral cavities in face-centered cubic metals. Layering at the liquid-solid interface plays an important role in determining physical properties as diverse as the rheological behavior of two-dimensionally confined liquids and the dynamics of crystal growth.

Journal Article↗

PubMed2002

Behavior of metal nanoparticles in the electron beam.

Fabrication and structural observation of In, Pd and Mo nanoparticles deposited on Si(110) substrates were performed in an ultrahigh vacuum field emission transmission electron microscope. In situ and/or dynamic observation of In nanoparticles showed fluctuation of their structures. The smaller particles of size of 3-5 nm showed frequent fluctuation, while the nanoparticles of more than 10 nm in size showed relatively slower fluctuation. The bigger nanoparticles showed coalescence with a weaker beam. Pd nanoparticles of size of 3-5 nm showed structural fluctuation after 10-30 s of electron beam irradiation. Stronger beam irradiation resulted in the dissipation of the nanoparticles probably due to diffusion. Mo nanoparticles of size of 3-5 nm never showed structural fluctuation. Intensive electron beam irradiation resulted in the dissipation of the particles. The difference in structural fluctuation depending on the metal and the beam intensity, and the peculiar coalescence of In nanoparticles are discussed qualitatively.

Journal Article↗