Effects of hydrothermal treatments (HTT) have been investigated on the merocyanine (MS) - Cd arachidate mixed Langmuir-Blodgett (LB) films. The as-deposited J-band is reorganized by HTT under the 100%-humidity condition in the range 30-90oC, forming a new phase with spectra sharper than those before HTT. The spectra after HTT can be deconvoluted into Bands I and II, Gaussian-type centered at 5I5 nm and 555 nm, respectively, and Band III, the remainder identifiable with the J-band with its peak at 590-600 nm. The relative fraction of oscillator strength of Band II is insensitive to both time tH and temperature TH of HTT. The Band-III and Band-I fractions are approximated by exponential saturation and decay functions of tH when TH=const, and by sigmoid and inverse-sigmoid functions of TH when tH=const, respectively. These suggest that the reorganization process is described as a first-order reaction between Band-I and Band-III components.

抄録全体を表示

Change in morphology of merocyanine - Cd aracbidate mixed Langmuir-Blodgett (LB) films has been studied before and after the hydrothermal treatments (HTT) of 100% humidity at temperatures ranging from 30oC to 90oC using a polarized light photomicroscope. By applying HTT, the J-band with an in-plane anisotropy in the as-deposited LB films is reorganized into an isotropic phase characterized with a narrowing of the peak Correspondingly, the microscopic image, initially anisotropic and featureless under polarized light, changes to be isotropic and filled with round-shaped domains as large as 0.1 mm or more in diameter. Observation of four types of LB samples with different monolayer stacks indicates that each domain is confined to one single monolayer.

抄録全体を表示

Hydrothermal and dry-heat treatments (HTT and DHT, respectively) in the morocyanine-containing LB films are studied in relation to the ‘mild’ heat treatment, which leads to two different consequences in the spectral change. Close resemblance is found between the HTT-type and the HTT spectra associated with a sharp J-band peak, and also between DHT -type spectra and the DHT ones with a broad band. It is suggested that the underlying processes of the HTT -type and the DHT -type are essentially identical with those of the HTT and the DHT, respectively. The seasonoodependent occurrence of the both types after the ‘mild’ HT suggests that the humid and cool weather leads to the high yield of the HTT -type spectra. The water remaining on the sample is presumably assumed to act as a humidifier to supply the sufficient amount of water for inducing the HTT -type spectral changes.

抄録全体を表示

In this study, thin films of 100-nm. polystyrene (PS) microspheres mixed with polyvinyl alcohol (PVA) were prepared, and changes in the attenuated total reflection (ATR) using surface plasmon (SP) excitation due to humidity adsorption were investigated. The PS microspheres contained luminescent dyes, and SP emission light due to these dyes was also observed. The sample configuration was prism /Ag film (50 nm) / sphere film structure. The ATR dip and SP emission peak angles shifted in line with the adsorption and desorption of humidity. Furthermore, the intensity of the SP emission light changed, and this was considered to be a result of the PVA swelling due to humidity adsorption. The humidity response of the ATR and SP emission light was repeatedly observed. The adsorbed mass was also monitored using a quartz crystal microbalance.

抄録全体を表示

Dye-sensitized solar cells have been fabricated using dyes of ruthenium, NKX-2553, rosehip, blueberry, coffee, and hibiscus, and the characteristics of the dye-sensitized solar cells fabricated have been measured. As a result, it is found that the conversion efficiency of the dye-sensitized solar cell in which ruthenium-dye is used is about 8%, whereas those of the dye-sensitized solar cells in which dyes of rosehip, blueberry, coffee, and hibiscus are used are 0.023, 0.019, 0.015, and 0.015 %, respectively. We have also proposed the perfectly solid-state dye-sensitized solar cell using the poly(dimethyl silane) thin film which is fabricated by the vacuum evaporation technique.

抄録全体を表示

Fullerene C60 has poor compatibility with polymers. Therefore, it is difficult to control the aggregation state in a polymer. To improve the compatibility with polymers, a bismalonate segment in which has 2-(2-methoxyethoxy)ethyl groups was introduced to a C60 skeleton. As a result, the C60 derivative showed high compatibility with several polymers, and it was easy to obtain the polymer films that C60 skeletons were dispersed homogeneously. The polyvinylcarbazole (PVK) based film containing either C60 or the C60 derivative (C60 skeleton: 1 wt%) was prepared and the electron charges trapped by the C60 skeletons were estimated. In consequence, the collected charges of the C60 derivative were approximately twice as large as those of C60. This result was speculated that the photocarrier generation efficiency of the C60 derivative was higher than that of C60, or the hopping conduction was not occurred easily in the PVK based film containing the C60 derivative.

抄録全体を表示

The purposes of this work are to prepare a low density carbon nanofiber (CNF) emitter by a spray spreading method and to investigate the performance of field emission. A sprayed paste was prepared with organic solution of tetrahydrofuran and also with binders of Au paste and Polycarbonate. The used CNF were massively synthesized by a thermal chemical vapor deposition and were burned to eliminate amorphous carbon and catalyst The diameter of the CNF was about 0.1 micro m phi. Two types of CNF were studied with the length of ca. 10-20 micro m (normal-CNF) and ca. 1.5 micro m (cut-CNF). In the normal-CNF emitter the current density at 10 V/micro m. was about 1.4mA/cm2 with an electric field enhancement factor beta of about 1000, while 0.08mA/cm2 with beta of 4500 in the cut-CNF emitter. It was confirmed that the isolated CNF do play an important role as effective emitter sites.

抄録全体を表示

Bis(4,6-diaryl-1,3,5-triazin-2-yl)arenes were prepared for new semiconductive materials, and their thermal and morphological natures were characterized. The glass formation properties of the materials were discussed with respect to the effect of the substituents and the molecular conformations. The carrier mobility measurement revealed that the bis-triazines showed ambipolar carrier transport capabilities in the films. We also demonstrated to fabricate an organic light emitting diode using the his-triazine as an electron transport layer.

抄録全体を表示

The ditetradecyldimethylammoniuim-Au(dmit)2 (2C14-Au(dmit)2) salt can be transferred onto solid substrates reproducibly up to 160 layers. The conductance of the 2C14-Au(dmit)2 film of single layer does not increase by the electrochemical oxidation and is less than 10-7 S. As for the samples with thickness more than two layers, the conductance increases with increasing the time of the electrochemical oxidation (Tox) reaching the maximum conductance, Gmax, and, then, decreases gradually. The Gmax increases from 10-6 S up to 10-3 S with increasing the thickness in the range of 2-4 layers obeying Gmax proportional to N7.9. We postulate that the macroscopic conduction paths are formed by the accumulation of the molecular layer in the thickness range of 2-4 layers. In the thickness range of 4-40 layers, the Gmax is approximately proportional to N (the least-square fitting gives Gmax proportional to N1.3), indicating that the molecular layers can be oxidized uniformly to give a uniform conductivity. In the range of 40-160 layers, however, Gmax is almost constant with the average value of 2.04 x 10-2 S, indicating that the surface layers cannot be oxidized effectively and do not contribute to the macroscopic conduction significantly if the total number of layers is more than ca. 40.

抄録全体を表示

We have studied the correlation between the conductance and Fourier transform-infrared (FT-IR) spectra of the Langmuir-Blodgett (LB) film based on ditetradecyldimethylamrnonium-Au(dmit)2 [2C14-Au(dmit)2] salt. The 2CI4-Au(dmit)2 salt was transferred onto a CaF2 substrate and was electrochemically oxidized using a constant current of 0.8 micro A in an aqueous solution of LiClO4. The conductance and the FT-IR spectra were measured using a slit between the electrodes by taking out the samples from the electrolyte and dried by nitrogen gas every thirty minutes. We have already reported that the conductance gradually increases with time of the oxidation up to 150 min but it turns to decrease modestly later. Accompanied by the oxidation, a broad band appears in a wide range of 850-7000 cm-1 and the peak shifts from 2000 cm-1 down to 1630 cm·1 in the first 120 min and it turns to be constant later. The area change of the IR spectra, which is proportional to the oscillator strength, is in close agreement with the conductance behavior. These results strongly indicate that the broad absorption is of charge transfer (CT) band and the conducting properties can be controlled precisely by monitoring the CT band together with the CH2 symmetric, CH2 antisymmetric and C=S stretching bands located at around 2850 cm·1, 2920 cm-1 and 1055 cm-1, respectively.

抄録全体を表示

We have produced LB films composed of [M(dmit)2]-[N(CmH2m+I)n(CH3)4-n] 1 : r ([M-(nCm)r]) complexes set in the bottom-contact-type Field-Effect transistor (FET) structure, where M = Au, Ni or Pd, m = 8, 10, 12, 14, 16, 18 or 22, n = 2, 3 or 4, and r = 1 or 2. We have measured the Ids-Vds characteristics of these LB films. The FET characteristics were observed in some cases. But the transconductivity of the devices has been found to be quite low. Moreover, an anomalous hysteric behavior of Ids-Vds characteristics has been detected for some complexes.

抄録全体を表示

We investigated the molecular orientation of organized molecular films with regard to solid-state structures for newly synthesized comb copolymers with N-vinylcarbazole (NVCz) by X-ray diffraction (XRD), surface pressure-area (pi-A) isotherm and in-plane XRD. In the bulk state, hydrogenated and fluorinated comb copolymers formed side-chain crystals for a two-dimensional lattice spacing of 4.2 and 5.0 A, respectively. In this case, it was suggested that the carbazole rings in the main-chain were arranged in opposition to each other. From the results of the DSC measurements, sharp-shaped melting peaks appeared in the relatively lower temperature side of the thermograms. This result supported the formation of side-chain crystals in the synthesized comb copolymers. These mono layers of the copolymers on the water surface were extremely condensed, except for the fluorocarbon:NVCz = 1:1 copolymer. From the in-plane XRD measurements of multilayers on solids, the changes in the two-dimensional lattice structure of fluorinated comb copolymer films containing NVCz units, as opposed to their bulk state, were confirmed. It seems that these structural changes are caused by the stronger pi-pi interaction between the carbazole rings rather than the van der Waals interaction between fluorocarbons.

抄録全体を表示

Molecular orientation and surface morphology of monolayers related to solid-state structure for methacrylate comb copolymers having fluorocarbon and hydrocarbon side-chains were investigated using X-ray diffraction (XRD), differential scanning calorimetry (DSC), and atomic force microscopy (AFM). From the XRD profiles, two kinds of short spacing peaks were confirmed at 5.0 and 4.2 A, which assigned the sub-cells for both side-chains. Further, two kinds of endothermic peaks, which corresponded to melting peaks of the both side-chain crystals, appeared in the thermograms. From the AFM observation of their mono layers, it was found that there were hydrogenated domains at a few hundred nm diameters in their monolayers, whereas corresponding acrylate copolymer monolayers form the phase-separated structure with the domains at 10-30 nm diameters.

抄録全体を表示

Molecular orientation in Langmuir-Blodgett (LB) films of newly synthesized ternary comb copolymers with N-vinylcarbazole (NVCz) and fluorinated side-chain was investigated using X-ray diffraction (XRD), differential scanning calorimetry (DSC) surface pressure-area (pi-A) isotherm, out-of plane and in-plane XRD, and atomic force microscopy (AFM). The results were compared with those of three-dimensional crystals. In the bulk state, these ternary comb copolymers formed side-chain crystals, which exhibited two-dimensional lattice spacing of 4.2 and 5.0 A. From the results of the DSC measurements, sharp melting peaks appeared in the relatively lower temperature side in the thermograms. This result supported the formation of side-chain crystals in the synthesized ternary comb copolymers. These copolymers formed extremely condensed monolayers on the water surface. From the out-of plane XRD measurements of multilayers on solids, formation of highly ordered layer structure were confirmed. From the in-plane XRD measurements of these multilayers, the two-dimensional lattice structures of ternary comb copolymer films containing NVCz units were different from that of their bulk state. These structural changes may be caused by the pi-pi interaction between the carbazole rings comparable with the van der Waals interaction between fluorocarbons.

抄録全体を表示

Develop of alignment control methods of microphase separated nanostructures in copolymers has been a subject of great demand. This paper shows the novel optical process for alignment control of nanostructures in a diblock copolymer composed of polystyrene and polymethacrylate with a liquid crystalline azobenzene-side chain. The aligned nanostructures were formed by exposure to linearly polarized light and subsequent annealing at suitable temperature. Exposure to interferometic argon ion laser beam also led to uniform alignment of nanodomains involved in a surface relief structure via photo-triggered mass migration with assist of liquid crystal.

抄録全体を表示

To study rheological properties of precipitated calcium carbonate (PCC) dispersion in dioctylphthalate (DOP) in the presence of a small amount of water, ca. 770-2600 ppm, the macroscopic viscosity was measured using a B-type viscometer. The PCC coated with stearic acid dispersed in DOP exhibited higher viscosity than the uncoated PCC. To know the mechanism of this high viscosity, the rheological properties of DOP in nanometer space were investigated using the shear resonance measurement. For this measurement, we used mica surfaces modified with dioctadecyldimethylammoniumbromide (DODA) as a model of PCC surfaces which bears long alkyl chains, and the effects of the surface modification and the addition of water to DOP were examined. For the 1164 ppm water content, we observed that the viscosity of DOP between DODA modified surfaces started to increase at the distance of 57.1 nm, which is much longer than the value for bare mica surfaces, 10.7 nm. When the water content was decreased to 469 ppm, the viscosity started to increase at small distances, 1.1 nm and 8.0 nm for the DODA modified and bare mica surfaces, respectively. These distances were compared with the average particle distance in a DOP sol employed for the macroscopic rheological measurement. Results of the current study indicated that a mechanism of the high viscosity of dispersion of PCC coated with long alkyl chains in DOP would be due to the increasing viscosity of DOP by the combined effects of water and long alkyl chains of the PCC surfaces.

抄録全体を表示

A biotin-terminated nanofiber-formable oligopeptide (1), which consists of 16-mer hydrophobic Leu and hydrophilic Lys, was newly prepared in order to modificate nanofiber surface through antigen-antibody interaction. The secondary structure and self-assembling properties of 1 in water were evaluated by means of CD and AFM measurements. As a result, the peptide 1 was found to form relatively short nanofibers, compared to those from biotin-free peptide 2, with beta-sheet conformation in aqueous solution at pH 9. On the other hand, biotin-containing beta-sheet nanofibers with high-axial-ratio were successfully obtained by mixing the peptide 1 with 2. ·Fluorescence, AFM and TEM measurements clearly revealed that streptavidin interacted with the 1/2-nanofiber, and was immobilized on nanofiber · surface. These results demonstrate the potential of this nanofiber as novel biomaterials with a wide range of applications, such as nano-scaffold and nano-template.

抄録全体を表示

We propose· easily renewable surface modification technique. A self-assembling peptide, RASDA16[CH3CO-(Arg-Ala-Ser-Ala)3-Arg-Ala-Asp-Ala-CONH2] was used as a component for a surface modification. This peptide forms a self-assembling hydrogel which could contain water as much as 99.5wt%. Then, the peptide was fixed on a silicon substrate to use a silane coupling agent. The peptide hydrogel was constructed on a silicon substrate by immersing in the peptide solution. The obtained substrate showed very high hydrophilicity. Furthermore, the wetting property of the substrate would be recovered by soaking the substrate in the peptide solution again, even if the peptide network on the substrate was removed. The hydrophilicity of the peptide-fixed substrate was efficiently recovered by RASDA16 adsorption on the substrate in a lower concentration of the peptide solution.

抄録全体を表示

Gold nanoparticles having sequential alternating amphiphilic peptide chains, Phe-(Leu-Glu)8, on the surface have been prepared. We described structural control of the amphiphilic peptide coated gold nanoparticle assembly by a conformational transition of the surface peptides. Under the acidic condition, the conformation of the surface amphiphilic peptide was converted to a beta-sheet structure from an aggregated a-helix by incubation. The plasmon absorption maximum of the gold nanoparticles shifted to a shorter wavelength with the formation of the beta-sheet assembly of the surface peptide. This suggests that the structure of the peptide coated gold nanoparticle assembly could be controlled by the conformational transition of the surface peptide. Furthermore, the core gold nanoparticle could be fixed in the beta-sheet assembly in the state that stood alone. This system may be useful for novel molecular devices that exhibit quantized properties.

抄録全体を表示

This paper describes synthesis and physicochemical properties of low molecular-mass organic gelators; 4-(2-perfluorooctyl)ethoxy- and 4-(2-perfluorooctyl)ethylthio-1 -alkoxybenzenes (compounds 1-n and 2-n). These compounds show remarkable gelation ability in various organic solvents, such as methanol, cyclohexane, acetonitrile, DMF, and so on. The critical gel concentration of 1-n is superior to that of 2-n; while the elongation of alkoxy chain length increase gelation ability in both compounds.

抄録全体を表示

Uniform ruthenium nanoparticles with an average diameter of 5 nm were prepared by polyol method and then deposited on acidic (Al2O3) and basic (MgO) type of supports. After conditioning, the catalytic activity of the supported Ru nanoparticles was tested for ammonia synthesis. The present study revealed some very interesting features of the nano-sized Ru nanoparticles (i.e. Ru-nano/Al2O3) as compared with the conventional catalysts (Ru-conv/Al2O3). In contrast to the conventionally prepared catalysts (by impregnation), the morphology of the well-defined Ru nanoparticles on the support was independent of metal loading. Thus, the TOF values in the kinetic region were not affected by metal loading. It was observed also that, the catalytic activity of the Ru nanoparticles was little affected by the nature of the support. Due to the minimization of the metal-support interaction, the Ru-nano/Al2O3 catalyst exhibited high activity for ammonia synthesis. The maximum reaction rate over Ru-nano/Al2O3 was at least one order of magnitude higher (around 925 micro mol g-1 h-1) than the rate observed over conventional Ru/Al2O3 catalysts. The activation energies for ammonia formation over alumina and magnesia supported Ru nanoparticles were 107 and 77 kJ mol-1.

抄録全体を表示

This work focused on the preparation of poly (vinyl alcohol) (PVA)/inorganic composites. Montmorillonite (MMT) and organically modified montmorillonite (OMMT) were used as the inorganic compounds. PVA/MMT and PVA/OMMT nanocomposites were prepared by solvent solution method. The morphology and interlayer spacing of the composites were characterized. Furthermore, the reaction mechanism between these Montmorillonites (MMT) and PVA was suggested that the hydrogen bonding and hydrophobic interactions contribute to the preparation.

抄録全体を表示

A photoresponsive chiral substituent consisting of dithienylethene moiety and chiral center was introduced into the side chain of bithienylene-phenylene copolymer. Reversible photoisomerization of the dithienylethene moiety was observed in both in CHCl3 solution and in cast film. Fluorescence of the polymer was quenched when the photochromic moiety changed from an open form to a closed one upon an irradiation of ultraviolet light. The quenched fluorescence was recovered through the reverse photoisomerization using visible light. Polarizing optical microscope demonstrated that the polymer has a main chain type liquid crystallinity. The polymer aligned by a rubbing technique exhibited a linearly polarized fluorescence (LPF). The cast film of the polymer showed Cotton effects in the region of pi - pi* transition of main chain in both circularly dichroism (CD) and circularly polarized fluorescence (CPF) spectra. The anisotropic fluorescence was controlled by the photochemical switching.

抄録全体を表示

Pure anatase crystalline phase was isolated from Degussa P25, a frequently used titanium(IV) oxide (TiO2) photocatalyst containing both anatase and rutile crystallites, by dissolving rutile phase selectively through treatment with aqueous hydrogen peroxide (H2O2)-ammonia (NH3). X-ray diffraction analyses revealed that pure crystallites have almost the same particle sizes in original P25, indicating that the purification process did not change their size distribution. Specific surface area measurement and scanning electron microscopic analysis also suggest that relatively smaller anatase crystallites were left undissolved by the H2O2-NH3 treatment.

抄録全体を表示

Electric conductance of the Au nanowires was investigated in 0.1 M Na2SO4 solution under electrochemical potential control using a mechanically controllable break junction setup with an electrochemical cell (EC-MCBJ). The conductance histogram exhibited a series of peaks, suggesting the existence of the stable diameter of the nanowires. Two different slopes were obtained in the plot of the stable diameter as a function of the peak index. The two slopes could be explained by the combination of the electronic and atomic shell effects. We could observe the shell structures in the conductance histogram of the Au nanowires under electrochemical potential control for the first time.

抄録全体を表示

Structure of the Ag and Au dot dimers arrayed on a glass substrate was optimized to exhibit intense surface-enhanced Raman scattering (SERS) of adsorbed 4,4'bipyridine molecule in an aqueous solution. The substrates with the Ag and Au dimers show clear optical anisotropy correlated to the polarization direction of the array. The SERS intensity also showed the same polarization anisotropy, suggesting that the gap of the dimer induced intense SERS. Empirical enhancement factor of the present system was estimated to be between 10^5 and 10^9. The SERS activity of the Au dimer was kept even under intense light irradiation, while the structure of the Ag dimer was damaged under the similar conditions. Localization of the SERS active site was shown by Raman imaging measurement. Polarization dependence of the SERS image proves that the uniformity of the structure of the Ag and Au dimer array showing intense SERS.

抄録全体を表示

Permeation behavior of gas molecules in ultramicropore was investigated by using molecular sieving carbon membranes. Hydrogen and hydrogen isotope (deuterium), which have the same molecular size but different mass, were used in order to discuss the diffusion mechanism. Although the temperature dependence of permeation coefficient apparently obeyed the Knudsen diffusion in the membranes which have wider ultramicropores, the deviation of the separation factor of hydrogen and deuterium from the theoretical value suggested coexistence of the other diffusion mechanism. With decreasing ultramicropore size, the permeation behavior of hydrogen deviated from Knudsen diffusion, indicating surface diffusion dominantly occurred. The stronger interaction of deuterium in ultramicropores was shown by the difference of activation energy of surface diffusion between hydrogen and deuterium. Apparent solubility factor, assuming surface diffusion, clearly showed that the deuterium is considerably adsorbed in ultramicropores more than hydrogen even at ambient temperatures.

抄録全体を表示

Electrochemical growth of ZnO/eosinY hybrid thin film was investigated. Two deposition potentials of -0.8 and -1.0 V vs. SCE were chosen to clarify the relationship between the redox state of eosinY and the structure of the products, because eosinY has its reduction potential at around -0.9 V. The hybrid thin film deposited at -0.8 V has a dense structure, while that at -1.0 V has a nanoporous structure. Almost steady current was observed during the potentiostatic electrodeposition. Deposition rates in film thickness, molar amount of ZnO and of eosinY were determined. Linear growth and constant composition were found regardless of the deposition potentials. The adsorption rate of eosinY at -1.0 V was about 10 times higher than that at -0.8 V. Because eosinY molecules can occupy as much as 38% of the total volume of the hybrid film deposited at -1.0 V, the film comes to possess an open porous structure after removal of the dyes by dipping the film in dilute KOH: On the other hand, eosinY molecules appear to be surrounded by ZnO due to the much lower loading efficiency at -0.8 V, so that the hybrid film is grown in a dense structure from which dyes cannot be fully removed by the KOH treatment.

抄録全体を表示

Gold nanorods dispersed in hexadecyltrimethylammonium bromide (CTAB) solutions were extracted with chloroform containing phosphatidylcholine (PC). Triple extractions decreased CTAB concentrations and gave PC-modified nanorods which adsorbed on an anionic glass surface. When more than 8.1 mM CTAB was retained in the nanorod solutions after the extractions, the nanorods dispersed stably without agglomeration. In order to have adsorption of the nanorods on an anionic glass surface, the residual CTAB after extraction should be less than 13.8 mM. Controllable adsorption was obtained between these concentrations.

抄録全体を表示

As novel organic modules in organic-metallic hybrid polymers, bromo-substituted bis(terpyridyl)benzenes were prepared via condensation of aromatic dienones with pyridinium salts in the presence of ammonium acetate. The organic-metallic hybrid polymer was obtained by complexation of dibromo-substituted bis(terpyridyl)benzene with iron(II) acetate. We investigated electrochemical and spectroscopic properties using cyclic voltammetry and UV-vis spectral measurement and revealed a substituent effect of the bromo groups.

抄録全体を表示

Ternary nickel-cobalt-phosphorus (Ni-Co-P) hollow microfibers could be prepared by electroless deposition on a hydrogen-bonded supramolecular aggregate as a fibrous template, followed by annealing at 600 °C under an argon atmosphere. Their chemical composition, crystallinity, magnetic property and morphology were characterized. The cobalt content in the hollow microfibers could be tuned simply by a choice of an electroless plating bath, mainly composed of NiSO4 and CoSO4 as metal sources and NaH2PO2 as a reducing reagent and containing different cobalt content expressed as [Co2+]/([Ni2+] + [Co2+]). The Ni-P hollow microfiber without cobalt showed ferromagnetism with a small coercive force, while saturated magnetization, residual magnetization and coercive force of the Ni-Co-P hollow microfibers decreased significantly with an increase of the cobalt content. The increase of the cobalt content induced simultaneously an increase of the phosphorus content. so that crystallization temperature to form a ferromagnetic f.c.c nickel phase was increased and thermal stability of the hollow structure could be improved.

抄録全体を表示

We have synthesized the alkyl-passivated Si nanoparticles by a solution route, and have carried out the various spectroscopic studies in order to investigate their intrinsic electronic structures and surface chemistry. Photoluminescence (PL) spectra of the n-butyl-passivated Si nanoparticles exhibit the strong ultraviolet-blue emission. Moreover, it is found that their valence-band maximum energies directly estimated from the synchrotron-radiation valence-band photoemission spectra correspond to the resonance features in the PL excitation spectra Therefore, it is concluded that the PL from the present Si nanoparticles originates from the electron-hole pair recombination between the modified valence-band and conduction-band due to the quantum size effect. From the synchrotron-radiation Si 2p core-level photoemission spectra, their interfacial electronic structures of these Si nanoparticles have been characterized. From these results, we discuss the detailed electronic and chemical properties of alkyl-passivated Si nanoparticles.

抄録全体を表示

Partially ordered FePt nanoparticles were obtained by using polyol reduction of metal salts in an autoclave at high reaction temperature. The resulting FePt nanoparticles synthesized at 400 °C had the particle sizes of 6-7 nm and could be easily redispersed into hexane, toluene and chloroform. Their crystal structure was found to be partially ordered L10 structure and the ordering degree was dependent on the reaction temperature and the reaction time.

抄録全体を表示

The effects of Al doping on luminescence properties of Er ions (Er3+) in Er and Si nanoparticles co-doped SiO2 are studied. The purpose of Al doping is to improve concentration quenching of Er3+ luminescence and to realize higher concentration Er doping. We show that the concentration quenching is slightly improved by Al doping. However, the luminescence intensity is decreased. In order to clarify the mechanism of photoluminescence (PL) quenching by Al doping, the PL rise and decay time were analyzed. The result indicates that the number of optically active Er is decreased by AI doping.

抄録全体を表示

Metal-particle-enhanced HF etching of Si can produce micrometer-sized macroporous and nanometer-sized microporous Si by simple immersion of metal-particle-modified Si in a HF aqueous solution without a bias or a particular oxidizing agent. The etching rate of Si and the structure of produced porous Si are changed by the dissolved oxygen concentration of the HF solution and the photoillumination intensity on Si during etching. In this study, we found that strong photoillumination promotes the etching of Pt-modified n-Si under the absence of dissolved oxygen in the HF solution. Pd particles show a unique behavior in which the etching of n-Si proceeds at a high rate accompanying hydrogen evolution under dark conditions and the absence of dissolved oxygen.

抄録全体を表示

The microscopic structures of two nano-structured inorganic films, one based on titania nanosheets (TNS) and the other on mesoporous silica (MPS), were investigated. The clear stacking structure of the TNS and MPS films were observed by the XRD, SEM, and TEM analyses. The selective adsorption of the porphyrin derivatives into the MPS nano-cavities and viologens into the TNS nano-layers was also investigated by absorption and energy-dispersive spectroscopy (EDS).

抄録全体を表示

The molecular recognition ion gating membrane, which is a bio-inspired membrane comprising the copolymer of N-isopropylacrylamide and benzo[18]-crown-6-acrylamide grafted onto the surface of a porous polyethylene film, responded to both a change in temperature and a specific ion signal. The gating membrane generated similar osmotic pressures to a dialysis membrane in the closed-pore state but not in the open-pore state. An optimized membrane structure was required for controlling this phenomenon. Generation of the osmotic pressure was closely related to the ion distribution through the membrane thickness.

抄録全体を表示

Atmospheric pressure continuous flow microplasma reactor was developed for the fabrication of silicon nanocrystals in gas phase. Mixture of argon, hydrogen, and silicon tetrachloride (SiCl4) was activated by non-thermal plasma generated in a capillary glass tube with a volume of less than 1 micro-liter. A microplasma reactor provides high-density reactive media where silicon precursor is efficiently decomposed into atomic silicon even though residence time is shorter than 10-100 micro s. Supersaturated silicon vapor gives rise to gas phase nucleation via three-body collision, followed by rapid termination of crystal growth due to short residence. time reactor. Silicon nanocrystal is thus obtained without post annealing process. Room temperature photoluminescence (PL) excited by He-Cd laser (325 nm) exhibited intense visible emission with peak intensity around 700 nm. The PL spectrum of as-grown sample was blue-shifted down to 540 nm with increasing hydrogen content; implying nc-Si core and oxide shell structures with core diameters of 1-3 nm. Green-liminescent silicon nanocrystals blue-shifted until 450 nm after natural oxidation in air.

抄録全体を表示

50-nm-thick amorphous Si films doped with 4.3 x 10^17 cm-3 phosphorus atoms were crystallized by thermal plasma jet (TPJ) irradiation. The electrical conductivity (sigma) of the crystallized films ranges from 1.2 x 10^-5 - 1.7 x 10^-2 S/cm, while Si films crystallized by excimer laser annealing (ELA) show much smaller sigma of 1.6 - 4.5 x 10^-6 S/cm regardless of laser fluence. This result can be interpreted that the defect density in the TPJ crystallized films is much smaller than that in ELA Si films. By treating the films with hydrogen plasma for 60 s at 250oC, sigma of TPJ crystallized films increased to 1.4 x 10^-2 - 1.1 S/cm, while it was 3.0 x 10^-6 - 6.5 x 10^-3 S/cm in the case of films crystallized by ELA. This result indicates that a short period hydrogenation is effective to improve the electrical characteristics of TPJ crystallized Si films.

抄録全体を表示

A high defect density of hydrogenated amorphous silicon (a-Si:H) is one of the main reasons for a low efficiency of a-Si:H solar cells. An increase in defect density of conventional a-Si:H is brought about by light exposure (light induced degradation). In the present work we employed a multi-hollow discharge plasma chemical vapor deposition (CVD) method to control the stability of a-Si:H films. The films deposited in the downstream region and in the upstream region near the discharges of the multi-hollow discharge plasma CVD reactor show light induced degradation, while ones in the upstream region far from the discharges show no degradation. The deposition rate of the species generated in the discharges decreases with increasing the distance between the substrate and the discharge, according to their surface reaction probabilities and diffusion velocities.

抄録全体を表示

We investigated the effects of substrate temperature on the deposition rates and the configuration of the hydrocarbon species in the film during film deposition in order to elucidate the film-deposition process. We have used infrared spectroscopy in multiple internal absorption reflection geometry (MIR-IRAS) to elucidate the configuration of the hydrocarbon species. The deposition rates drastically decreased as the substrate temperatures increased up to 200 °C. IRAS data revealed that the intensity of the peak due to the CH3 species decreased as the substrate temperature increased up to 200 °C. This suggested that the CH3 species preferentially decomposed and/or was etched during film growth at higher substrate temperatures.

抄録全体を表示

The removal efficiencies of organic impurities existing on the surface of silicon wafers by O2, H2, and N2O ECR plasma cleaning techniques were compared based on the Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR) analysis results. It was found that oxygen ECR plasma was the most efficient and hydrogen ECR plasma was the least efficient in removing organic impurities on Si wafers. In ECR oxygen plasma cleaning, the plasma exposure time to reach the detection limit of ATR-FTIR was 40s. Also the contaminants removal mechanism in O2, H2, and N2O ECR plasma cleaning have been discussed.

抄録全体を表示

Magnetron discharge is maintained with very low target DC voltages (100-200 V) by applying 40 MHz VHF power to the target, without decreasing sputter deposition rate. From measurement of Ar+ energy distribution function (EDF) and simulation of Ar+ and Ar EDFs, it is confirmed that the VHF-DC magnetron discharge suppresses the maximum kinetic energy of backscattered Ar atom. This magnetron sputter source is applied to the deposition of magnetic multilayer film for perpendicular magnetic recording. From measurements of atomic force microprobe, the VHF-DC magnetron sputtering shows drastically-improved film flatness, compared with conventional DC magnetron sputtering.

抄録全体を表示

The Co33Fe65 magnetic thin films with Cu underlayer were prepared and characterized using RF magnetron sputtering. Nano under layer effects on the magnetic properties and crystalline structure of the film were investigated for the GHz frequency use. It was found that the underlayer was very effective in inducing elongation of lattice parameter, preferred crystalline orientation, and decrease of crystallite size. These effects were attributable to a reduction of surface energy in the underlayer and led to improve remarkably the magnetic properties for the GHz frequency use above 10 GHz.

抄録全体を表示

A GaN thin film was fabricated by near-atmospheric plasma-assisted chemical vapor deposition. Pure nitrogen plasma can be generated stably using an alternating pulsed voltage system that applies an alternating pulsed voltage between two parallel plate electrodes. The excited nitrogen species correspond to the N2 second positive system. Ionic molecular species, which cause film damage, were not observed by optical emission spectrum analysis. Using this plasma as a nitrogen source, metalorganic chemical vapor deposition of GaN thin mm was carried out under a nitrogen partial pressure of 40 kPa and substrate temperature of 400oC. The quality of the GaN thin film was analyzed by means of 2-dimensional X-ray diffraction and X-ray pole figure measurement. The measurements revealed that the film was epitaxial with a 30o rotation of the unit cell with respect to (0001) sapphire in the (0001) basal plane.

抄録全体を表示

We studied effect of pressure on inductively-coupled plasmas sustained with multiple low-inductance internal-antenna units. With increasing pressure, the plasma densities on the substrate folder increased to attain a plasma density of 1.4 x 10^11 cm-3 at an argon pressure of 13 Pa. The plasma potential and the potential drop decreased drastically with decreasing Ar pressure. These dependencies are related to changes in the electron temperature and the antenna RF voltage. The ion energy distributions considerably decreased with increasing Ar pressure. The peak energies of the distributions depended more strongly on pressure and corresponded to the magnitude of plasma potential. The FWHM of the distributions decreased with lowering the antenna RF voltages by decrease in Ar pressure.

抄録全体を表示

Profiles of argon plasma sustained with multiple low-inductance antenna (LIA) units in a 300-cm rectangular plasma source have been investigated by a three-dimensional plasma simulation using fluid model. Profile of 4s excited Ar (Ar*) density was investigated as well as plasma density profile. It is found that FWHM of the profile for Ar* density is larger than 2 factors compared to that for density of Ar plasma sustained with two LIA units were installed at the center of top plate. This difference is caused by the different diffusion for particles; i.e., Ar ions diffuse along the electric field gradient while 4s excited Ar particles follow the diffusion of neutral argon. With multiple LIA units, the nonuniformity of the plasma density was 5.5% while that of Ar* density was 4.9% in 230-cm rectangular area, which is equivalent to the substrate size required for next generation flat-panel display processes.

抄録全体を表示

Transport of nano-particles in amplitude modulated (AM) RF discharges has been investigated using two-dimensional laser-light-scattering (2DLLS) method. By using the modulation, nano-particles can be transported rapidly, at a velocity more than 60 cm/s, from their generation region towards the upper grounded electrode during the modulation period. Two key parameters for the rapid transport are the discharge voltage VAM and the period delta t of the modulation. The rapid transport is realized for delta t longer than a threshold delta t value and VAM larger than a threshold VAM value. The threshold delta t value increases with the discharging period Ton, that is the size of nano-particles.

抄録全体を表示

We have tried modification of Y3Fe3O12 nanoparticle films in high-density RF plasmas sustained at high operating gas pressure. Experiments for pure Ar plasma showed phase separation which occurred by oxygen deficiency and no phase transformation to YIG. Modification by adding Ar gas to oxygen gas results in significant structure change. These results suggest that the plasma sustained for Ar+O2 mixture gas have enough enthalpy for phase transformation. The addition of oxygen in Ar plasmas is effective for suppression of phase separation and enhancement of phase transformation to YlG. Rate of phase transformation in high-density plasma is fast compared to that in conventional annealing using electric furnace which requires for 30 min at 900 °C to transform to YIG.

抄録全体を表示

The innovative in-flight glass melting technology with thermal plasmas was developed for the purpose of energy conservation and environmental protection for glass production. Modeling and experiments of induction thermal plasmas have been performed to investigate the melting behavior of granulated powders injected into thermal plasmas. The thermofluid fields were obtained by solving two-dimensional modeling for argon plasmas under atmospheric pressure. Results show the strong influence of carrier gas flow rate on the melting behavior. With flow rate increasing, the particle size and temperature of glass transition and softening decrease, whereas the amount of unreacted SiO2 increases because of lower plasma temperature and shorter residence time. The experimental results are consistent with the model, which gives valuable practical guidelines in optimizing the process parameters and controlling the product characteristics.

抄録全体を表示