Masaru Miya

Gold nanoparticles ion implanted in glass with enhanced nonlinear optical properties

Silica glass with dispersed colloid Au particles was synthesized by ion implantation. Colloid Au particles were found to grow through an Ostwald ripening mechanism controlled by diffusion in the silica glass. The third‐order nonlinear optical susceptibility χ(3) of this glass was found to be proportional to the fourth power of the radius of the colloid particles or the fourth power of the absorption coefficient at the peak of a plasmon band when the total volume of the colloid particles was constant. Furthermore, χ(3) of the glass was inversely proportional to the third power of the total volume of colloid particles when the absorption coefficient of the plasmon band was constant.

Au + -Ion-Implanted Silica Glass with Non-Linear Optical Property

Au+ ions have been implanted in silica glass at an acceleration energy of 1.5 MeV and a fluence level of 1017 ions/cm2. The Au ions form colloid particles with the radius of 2.9 nm after heat treatment. The glass with Au colloid particles shows the large third order non-linear susceptibility; χ(3)=1.2×10-7 esu. The large χ(3) value of the glass is attributed to the high concentration of Au colloid particles in the narrow region.

Mesomorphic phase transitions of tetraphenylporphyrins with four long aliphatic chains

Abstract Studies of 5,10,15,20-tetrakis(4-n-alkylphenyl)porphyrins revealed that the homologues with longer alkyl chains than hexyl were mesomorphic, in contrast to the non-mesomorphic alkoxy derivatives. Metal complexes (Co, Ni, Cu, Zn, and Pd) of the dodecyl derivative were also shown to exhibit mesophases. These mesophases were assigned as discotic lamellar (DL) phases by X-ray diffraction studies.

Total internal reflection Raman spectroscopy

Feasibility of total internal reflection (TIR) Raman spectroscopy as a new tool for characterizing thin surface layers has been investigated, starting with selection of the material for the internal reflection element (IRE). Sapphire was found to be the most suitable for the IRE among TiO2, SrTiO3, several kinds of flint glasses, and sapphire itself. The potential of TIR Raman method was proved by measurements on the two‐layered samples consisting of a thin surface layer of polystryene and a base layer of polyethylene. The thickness of the surface layer that could be measured by the present technique was then extensively investigated for the two‐layered samples which had the surface layer of polystryrene varying in thickness (0.006–0.93 μm) and the base layer of a constant thickness of polycarbonate (12 μm). We could measure vibrational spectra of the surface layers as thin as 0.006–0.2 μm sufficiently separately from those of the base layer. Thickness of the measurable surface layer could be varied to a ...

Preparation and optical property of monolithic silica gel uniformaly dispersed with gold colloid from aqueous solution

Abstract Gold colloids were prepared from aqueous HAuCl4 solutions ranging in concentration from 0.01 to 0.05 wt% by reducing with sodium citrate and dispersed in a monolithic disk, with 35 mm diameter and 1 mm thickness, by the sol-gel method. Tetramethoxysilane is the only useful reagent as Si source. The particle size of dispersed gold colloids was about 50 nm. This silica gel had a third-order optical non-linearity and its susceptibility, χ(3), was about 7×10−12 esu.

Total Internal Reflection Raman Spectroscopy at the Critical Angle for Raman Measurements of Thin Films

Total internal reflection Raman spectroscopy at the critical angle has been shown to be useful for Raman measurements of not only thin films but also of any samples that can be directly coated or intimately contacted on the internal reflection element (IRE). Usefulness of this technique was demonstrated for a polystyrene film (0.70 μm thick) coated on the IRE, signal enhancement being 40 as compared with the conventional normal illumination. The technique was also applied to a thin coating layer of bovine albumin on the IRE to give the spectrum of excellent signal/noise ratio.

Nonlinear optical properties of silver sols prepared by photoreduction method

Abstract The third-order nonlinear susceptibility ( χ (3) of silver sol prepared by a photochemical method was measured by the degenerate four-wave mixing method. The χ (3) of the silver sol of brown-green color was larger than that of yellow-brown color. The photo-induced aggregation of silver particles affects the χ (3) of the sol. It has been found that the χ (3) of the silver sol is proportional to the intensity of surface-enhanced raman scattering from carboxylate ions adsorbed on the silver particle. The increase of χ (3) by the enhanced local electric field due to surface plasmon resonance is proposed.

Formation of Au Colloid Particles in Silica Glass by Ion Implantation.

Formation of Au colloid particles and their optical property have been investigated in silica glasses implanted with Au + ions at an acceleration energy of 1.5MeV and fluence levels of 10 16 -10 17 ions/cm 2 . The Au colloid particles are formed in the as-implanted glasses. It is inferred that the average radius of Au colloid particles depends on the fluence level, although the fluence level does not affect the distribution of Au atomic concentration. The heat-treatment little affects the Au atomic distribution. The Au colloid particles grow to 4.3nm in average radius during heat treatment. It is revealed that the large nonlinear optical property of the Au + -ion-implanted silica glass is attributed to the high concentration of the Au colloid particles in the narrow region.

Synthesis and mesomorphic behaviour of oxo[5,10,15,20-tetrakis(4-n-dodecylphenyl)porphinato]molybdenum(V)

Abstract Oxochlor0[5,10,15,20-tetrakis(4-n-dodecylphenyl)porphinato]molybdenum(V) wav synthesised and found to exhibit a mesophase of lamellar type. This is the first discotic metallomesogen possessing two different axial groups. The effect of the axial ligands on the mesomorphic properties was preliminary discussed in comparison with the results of the hydroxoaluminum analogue.

Optical non-linear property of Au colloid-doped glass and the laser irradiation stability

The optical non-linear property of an Au colloid-doped glass was measured by degenerate four-wave mixing (DFWM) experiments using a frequency-doubled Nd:YAG laser with 7 ns pulse duration. The pulse duration of the phase-conjugate reflection was 4 ns, indicating the fast response time of the glass. The third-order susceptibility χ(3) was estimated to be 2.5 × 10−11 e.s.u. (3.5 × 10−19 m2 V−2). The photodarkening effect was not observed and the phase-conjugate reflection was stable against the laser irradiation.