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We studied polydimethylsiloxane nanocomposites with oxides such as TiO2, SiO2, and Al2O3 aiming at proton beam writing (PBW) of buried optical waveguides. Relatively high transmission was achieved for 1.0 wt% TiO2/PDMS composite without aggregation. The refractive index can be tunable by varied TiO2 concentration in nanocomposites. We evaluated refractive index changes by 1.0 MeV proton irradiation. Refractive index of TiO2/PDMS nanocomposite increased at low fluence of less than 100 nC/mm2 and then decreased at higher fluence. On the other hand, we observed monotonic increase of the refractive index as a function of fluence for PDMS and PDMS nanocomposites with SiO2 and Al2O3. We also compared thermo optic effect of PDMS nanocomposites. We evaluated buried optical waveguides in TiO2/PDMS nanocomposite written by PBW for near field patterns with single mode waveguide.

Focused Hydrogen Molecular Beam (FHIB) is an extended technology to utilize accelerated proton to modify material that is Proton Beam Writer (PBW) Watt (1999) [1]. The unique characteristic of these technologies is their capability to modify engineering plastics such as polyester and polyimide of no photosensitivity. These engineering plastics are key materials to compose electronic circuits and devices. Therefore we have been researching to apply these technologies for making functional devices in various applications. FHIB especially H3+ as the accelerating particle is proposed to improve productivity for industrial products Hayashi et al. (2017) [2]. In this report we show FHIB is properly applied to make distributed surface device of low profile that is useful to surface devices working at GHz to THz band applications. These bands are expected to provide the last communication carrier to fulfil the future wireless communication needs Oshima et al. (2017) [3]. We used 1MV accelerator to accelerate H3+ and irradiated on the FPC surface before development process of 5% KOH to make engravings and nanometer sized silver oxide paste was used to fill.

We performed dielectrophoresis (DEP) of Au colloidal particles using PMMA pit arrays fabricated by proton beam writing. Frequency dependence of DEP shows the collection of nanoparticles at pit arrays is most efficient at the AC voltage frequency of 1 kHz. The application of DC voltage during DEP also helps transport and supply of nanoparticles to the pit arrays. Gradual increase of the AC voltage amplitude should be taken into consideration to avoid damage effects on indium tin oxide electrode by joule heating.

Solid-state organic fluorescent materials are important for the development of electroluminescent sensing devices. Herein, we report that N,N′-bis((R)-1-phenylethyl)perylene-3,4,9,10-tetracarboxylic diimide [(R,R)-BPP] and its antipode [(S,S)-BPP], which contain extended π-electrons through planar perylenes, emit solid-state aggregation-induced-enhanced (AIEnh) circularly polarised luminescence (CPL) in inorganic (KBr) pellets and organic-polymer-film (PMMA- and myo-IPU-film) states; this CPL is difficult to observe in solution. These chiral perylene fluorophores emit AIEnh-CPL with high dissymmetry factors (gCPL) (up to 2.4 × 10−3) and high quantum yields (ΦF, up to 0.43) in the three solid matrices.

Proton beam writing (PBW) on SU-8 composites with nanoparticles (size: 14–750 nm) of silver, silica, alumina, and carbon with concentration of 5.0 wt% was studied aiming for high-aspect-ratio micro-structuring. Results of SRIM simulation suggest that deep micromachining of more than 100 μm is possible by 3.0 MeV PBW with increase in lateral straggling of less than 5.0%. Sensitivity loss of 150% was observed by introduction of 5.0 wt% nanoparticles to SU-8. There is a correlation between the sensitivity loss and volume concentration of nanoparticles. We fabricated pillar arrays of SU-8/silver nanocomposites with 10 μm in diameter and 80 μm in height by PBW at 3.0 MeV. Cross-sectional observation of the SU-8/silver pillar arrays shows that silver nanoparticles are homogeneously dispersed in SU-8, while aggregation was observed at the side surface.

In this study, we fabricated thick films with polyvinylpyrrolidone (PVP) added to bismuth titanate (Bi4Ti3O12) to form a lead-free ferroelectric material. We examined the direct patterning of these materials by using proton-beam irradiation. When 50% PVP was added to the organic source solution, the c-axis orientation was promoted and cracks were suppressed due to stress relaxation. In addition, a dot and an arbitrary-shape micro-pattern were formed on bismuth-titanate thick film by micromachining using a proton beam.

A focused 750 keV proton microbeam was used to fabricate an embedded Mach–Zehnder (MZ) optical waveguide in a polydimethylsiloxane (PDMS) film for interferometer application. The sample position was precisely controlled by a mechanical stage together with scanning microbeam to form an embedded MZ waveguide structure within an area of 0.3 mm × 40 mm. The MZ waveguides with core size of 8 μm was successfully embedded in PDMS film at a depth of 18 μm by 750 keV proton microbeam with fluences from 10 to 100 nC/mm2. The MZ waveguides were coupled with an IR fiber-laser with a center wavelength of 1550 nm and evaluated by using the transmitted intensity images from an IR vidicon camera. The results indicate that the embedded MZ waveguide structure in PDMS achieved single spot light propagation, which is necessary for building optical switching circuits based on polymer MZ waveguides.

Polydimethylsiloxane (PDMS), a type of silicone rubber, has excellent material properties such as flexibility, optical transparency and biocompatibility. Therefore, it can offer possible applications in the field of microfluidics as flexible micro-optical components, when they can be formed on transparent materials such as silica glass. We performed proton beam writing (PBW) (with 1.0 MeV beam) on PDMS microstructures with curved surface on silica glass. We found that 13-μm thick PDMS films on silica glass are sensitive only for proton fluences above 600 nC/mm 2 in contrast with the sensitivity of 4.0 nC/mm 2 when using a silicon substrate. Based on the hypothesis that the effective sensitivity was lower due to the electric charging of silica glass surface during PBW, we coated the silica glass surface by Au sputtering. As a result, we were able to observe the formation of PDMS on the Au-coated silica glass at a much lower fluence of 2.0 nC/mm 2 . Arrays of curved PDMS structures with a height of 13 μm and diameter of 40 μm have been fabricated on a semi-transparent Au-coated silica glass.

A simple and sensitive sub-micrometer scale method for visualization of the dose distribution of a focused proton beam (FPB) was developed, taking advantage of the formation of a bulky crosslinked structure induced by FPB irradiation of a common polymer and cross-linker, polyacrylic acid-N, N'-methylene bisacrylamide, blend film surface. The irradiated part of the film swelled as a peak, and the height of swelling increased with increasing FPB fluence. The film was used as a proton beam-sensitive polymer film by analysis of the irradiated film surface using atomic force microscopy. The method was successfully applied to confirm the FPB pattern. Typical misaligned spot shape of FPB gave clear 3-dimensional structures, and the half-solenoidal nanostructures are visualized clearly by use of crescent shaped beam.

Proton beam writing (PBW) has attracted much attention recently as a next-generation micro-fabrication technology. It is a direct-drawing technique and does not need any masks to transfer micro-patterns to sample surfaces. In addition, the refractive index of a poly (methyl methacrylate) (PMMA) can be increased by proton-beam irradiation. In this study, we fabricated the first 1.5-μm-band single-mode, straight-line waveguides and Y-junction waveguides consisting of PMMA layers using the PBW technique.

Since 1990 R&Ds of microbeam technology has been progressed at the TIARA facility of JAEA Takasaki. In order to meet a wide variety of ion beam applications, analysis, radiation effect studies, or fabrication in regions of micro- or nano-structures, three different types of ion microbeam systems were developed. In these systems, high-spatial resolutions have been achieved and techniques of micro-PIXE, single ion hit and particle beam writing (PBW) were also developed for these applications. Microbeams, on the other hand, require the highest quality of beams from the accelerators, the cyclotron in particular, which was an important part of the microbeam technology of TIARA. In this paper, the latest progress of the ion microbeam technology and applications are summarized and a future prospect of them is discussed.

Proton beam writing (PBW) was applied for micromachining of a PMMA mother for Ni electroforming. Proton beam focused down to about [email protected] at beam energy of 1.0-3.0MeV was used for PBW on a PMMA layer on Si or Cu substrate. Using modified techniques for developing of [email protected] thick resists exposed to PB and electroforming steps, fabrication of the Ni structures with aspect ratio up to 30 by electroforming with a [email protected] thick PMMA mother micromachined by PBW was successful. We also tried thermal imprint using a [email protected] thick Ni microstructure on Cu substrate with an aspect ratio of more than 4 on a PMMA film.

In the title compound, we made X-ray satellite reflection measurements up to 0.7 GPa and angle-dependent magnetoresistance (AMR) measurements at 1.9 GPa. The purpose of the study is to clarify (1) how large the temperature-pressure regime is for the long-range charge ordering (CO), (2) whether or not the high pressure regime for the superconductivity is really a metallic state, and (3) what the electronic properties are in the intermediate pressure regime between the long-range CO and the superconducting states. The long-range CO was found to be stable up to 0.7 GPa, and its temperature-pressure regime coincides with that expected from transport measurements. AMR at 1.9 GPa, 1.4 K and 12 T suggests the presence of Fermi surfaces consistent with band calculations based on X-ray structural analyses at room temperature and the same pressure. Raman studies by one of the authors (K.Y.) suggest the presence of metallic state in the intermediate pressure regime where the resistance shows apparently insulating properties. Discussion is made on the role of the charge-degree of freedom in causing the superconductivity.

Doping has become crucial for achieving stable and high-performance conductive transparent carbon nanotube (CNT) films. In this study, we systematically investigate the doping effects of a few materials including alkali metal iodides, nonmetal iodide, and metals. We demonstrate that photonic curing can enhance the doping effects, and correspondingly improve the conductivity of CNT films, and that such iodides have better doping effects than metals. In particular, doping with a nonmetal compound (NH4I) shows the largest potential to improve the conductivity of CNT films. Typically, doping with metal iodides reduces the sheet resistance (R S) of CNT films with 70–80% optical transmittances at λ = 550 nm from 600–2400 to 250–440 Ω/square, whereas doping with NH4I reduces R S to 57 and 84 Ω/square at 74 and 84% optical transmittances, respectively. Interestingly, such a doped CNT film exhibits only a slight increase in sheet resistance under an extreme environment of high temperature (85 °C) and high relative humidity (85%) for 350 h. The results suggest that photonic-curing-induced iodide doping is a promising approach to producing high-performance conductive transparent CNT films.

Proton beam writing (PBW) was applied to the fabrication of dielectrophoretic (DEP) devices equipped with high-aspect-ratio pillar arrays. With coupled use of soft lithography for micro-fluidic channels, we successfully fabricated a device equipped with SU-8 pillar arrays produced by PBW, which is covered with a poly-dimethylsiloxane (PDMS) micro-fluidic channel. For more simplified prototyping of the device, we modified a SU-8 mold for simultaneous replication of both pillar arrays and micro-fluidic channel on PDMS. Replication of pillar arrays is limited to the aspect ratio of less than three.

Fabrication of high-aspect-ratio microstructures was performed by proton beam writing (PBW) using a microbeam line at Takasaki Ion Accelerators for Advanced Radiation Application (TIARA), JAEA Takasaki, JAPAN. As one of the applications of the high-aspect-ratio structures micro-machined by PBW, we utilized the high-aspect pillars for electric-micro filters of microbes such as Escherichia coli and Yeast based on the dielectrophoretic force. The filter is equipped with high-aspect pillars with a height of ∼20 μm and a diameter of ∼1 μm on a glass plate. Evaluation of the dielectrophoresis (DEP) device for capturing E. coli and Yeast was made using either observation by optical microscope or photoluminescence (PL) measurements.

In TIARA facility of Japan Atomic Energy Agency (JAEA) Takasaki, we have produced three-dimensional micro/nano-structures with high aspect ratio using cross linking process based on negative resist such as SU-8 by a technique of mask less ion beam lithography. By bombarding high energy heavy ions such as 450 MeV Xe 23+ to SU-8, on the other hand, it appeared that a nanowire could be produced just with a single ion hitting. Then we tried to produce nanowires, of which both ends were fixed in the three-dimensional structure. This paper shows a preliminary experiment for this purpose using a combination of 15 MeV Ni 4+ ion microbeam patterning and the 450 MeV 129 Xe 23+ hitting on SU-8.

Proton beam writing (PBW) is one of the direct write techniques for the purpose of deep micromachining. Together with the flexibility of the direct write feature, micromachining of high-aspect-ratio structures is possible due to the straight trajectory of the MeV energy protons. However, direct writing is a low throughput process, when compared with a mask process such as UV lithography. For better productivity, coupled use of PBW with electroplating has been proposed as a method to fabricate metal microstructures for molds of imprint lithography. We demonstrate the electroplating of high-aspect-ratio Ni microstructures on PMMA micromachined by PBW.

Dielectrophoresis (DEP) is a phenomenon involving translational movement of a polarizable object toward the direction of the electric field gradient. DEP has been used for electrical trapping of food poisoning microbes such as Escherichia coli (E. coli). In this paper, we developed 3D-electric micro filters equipped with high-aspect-ratio pillar array with a height of ~15 @mm and a diameter of ~1 @mm as a part of the electric micro filter. The pillar array was fabricated using a 15 micrometer thick negative resist layer on silica substrate by proton beam writing (PBW). We analyzed a DEP force distribution around pillars in the 3D-electric micro filters. Making the most of superior features of PBW as a rapid prototyping tool, we evaluate the performance of the DEP device for trapping capability of E. coli by photoluminescence (PL) measurement for various arrangements of the pillars to achieve higher trapping efficiency of the 3D-electric micro filter.

Micropatterning of two types of siloxane films, HSQ and SOG was studied by 1.0 MeV focused proton beam. FT-IR measurements show the transformation of the Si-O-Si structures in siloxane to networked structures after proton beam writing. Both the HSQ and SOG are negative resist for 1.0 MeV proton beam. Lines with smooth sidewalls were written by proton beam writing for both HSQ and SOG. Vertical sidewall is observed for HSQ, while it is tapered for SOG.

In this paper we report fabrication of high-aspect-ratio micro-structure of Ni by electroplating, using a micro-machining technique of resists using proton beam writing (PBW) at Japan Atomic Energy Agency (JAEA). A micro-structure of 5 μm thick PMMA was fabricated by exposure using PBW at 1.7 MeV and by development. A Ni structure was then formed by electroplating on the micro-structure of PMMA. Vertical and smooth side walls observed by a scanning electron microscope (SEM) indicate that PBW can be a versatile tool for fabrication of resists and metal microstructure in combination with electroplating. The electroplated Ni structure can be used as a resolution standard, which enabled us to focus the proton beam down to 130 nm.

Structural and optical properties of silica glass induced by ion microbeam irradiation were studied using micro- photoluminescence (μ-PL) spectroscopy and atomic force microscopy (AFM). Ion microbeam irradiation was performed using microbeam lines of 3-MV single-ended or tandem accelerators with various ion species including H+, He+, B3+, C4+, N4+, O4+, and Si5+ at energies of 1.7 to 18 MeV. The beam was focused to about 1 μm and was scanned over the surface of high-purity silica glass with fluences of 1013 to 1018 ions/cm2. The μ-PL spectrum in microbeam-irradiated silica shows two peaks at 540 and 650 nm. The mapping of the two PL bands reveals the distribution of defects induced along the track of ions. The compaction was observed in the form of groove at the surface of silica glass by AFM. The depth of the surface groove increases with increasing ion fluence and saturates at about several hundreds to 900 nm, depending on irradiated ion species. The mechanisms of structural and optical modifications of silica glass are can be understood in terms of energy loss due to electronic stopping and nuclear stopping powers. Refractive index changes with an order of 10– 4 to 10− 2 were estimated by a Lorentz–Lorenz relationship from the compaction. Technological implications of these results are also to be discussed.

We report micro-machining of resists on silicon by proton beam writing (PBW) at Takasaki Ion Accelerators for Advanced Radiation Application (TIARA), JAEA Takasaki, Japan. We studied the proton beam irradiation effects on typical positive and negative resists such as PMMA and SU-8, respectively, for application of the PBW technique to micro-machining. These resist materials were subjected to the scanning of a focused beam of protons accelerated using the microbeam facility of TIARA. Diameter of the proton beam was focused to about 1 μm. The fluence was varied to examine the irradiation effects on these resists as a function of the beam current and irradiation time. After exposure to proton beam, samples were developed and evaluated by a scanning electron microscope. Attempts to fabricate nickel stamps were also made by electroplating on the structures formed by PBW for application to imprint lithography.

We investigated the correlation between the luminescence properties and the surface structures of submicron silica particles prepared by the Stober method. After annealing in a non-oxidizing atmosphere, the submicron-sized silica particles show a broad photoluminescence (PL) band at 500–540 nm by excitation at an ultraviolet wavelengths (254 and 365 nm), and the one at the 600 nm by excitation an Ar + laser (488 nm). The PL appeared to result from the removal of impurities and subsequent formation of several luminescent structures on the internal surface of the primary particles by thermal annealing.

New C60-TTF dyads with several substituents on the TTF moiety were prepared to examine the substituent effect on the intramolecular charge transfer interaction. Cast films of the dyads with long alkyl chains were obtained with high quality and characterized. In X-ray diffraction study for the cast film of the derivative with -SC16H33 groups ( 1g ), high ordered reflection peaks were observed. Analysis of the diffraction pattern revealed that 1g forms the multibilayer structure in condensed film.

Radical salts based on DODHT [(1,4-dioxane-2,3-diyldithio)dihydrotetrathiafulvalene] are semiconductors at ambient pressure, but some salts (PF6, AsF6, and BF4·H2O salts) exhibit supuerconducting transition under hydrostatic pressure. X-ray diffraction and magnetic susceptibility measurements at ambient pressure for PF6 salt revealed that the insulating phase at ambient pressure corresponds to a charge ordering (CO) state with stripe-type charge pattern. While the similar magnetic behavior was observed for BF4 salt, temperature dependence of magnetic susceptibility of AsF6 salt is quite different from those of the other salts.

A new TTP donor, Me-DH-TTP (2-methyl-5-(1,3-dithiolan-2-yliden)-1,3,4,6-tetrathiapentalene), was designed to realize a system with large on-site Coulomb repulsion as compared with the previously known bis-fused type TTP donors. Probably as a consequence, (Me-DH-TTP)2AsF6 exhibits semiconducting behavior from room temperature to liquid helium temperature. By increasing pressure, metallic behavior appears below 300 K, and with distinct metal-insulator (M-I) transition up to 2.2 GPa. This M-I transition suddenly disappears beyond 2.5 GPa, and metallic state is stabilized down to 2.6 K. We discuss the possibility of quantum critical point around 2.4 GPa.

The detailed topology of the Fermi surface of the quasi-one-dimensional conductor (DMET)2I3 was investigated by the magnetooptical measurements. A pair of planar Fermi surface which has higher corrugations of Fourier components was observed. This result seems to suggest that the metallic state of this salt is stabilized by the higher corrugations of the Fermi surface.

High-purity silica glass was irradiated by a focused 15-MeV O 4+ microbeam with diameter of 1 μm up to a fluence of 1.0 × 10 14 ions/cm 2 . Spatial distribution of irradiation effects by the O 4+ microbeam on silica glass was investigated by optical microscopy, microphotoluminescence (PL)/Raman spectroscopy and atomic force microscopy (AFM). Distribution of refractive index change and defect formation was visualized by optical microscopy and PL mapping, indicating the structural changes of silica glass along the ion track up to the depth of 10 μm. In addition, we observed deformed side surface with a groove by AFM along the track suggesting the internal compaction in silica glass. This is accompanied by increased threefold rings of SiO 2 network detected by Raman scattering. We also discuss technological implications of these results on the applications of microbeam irradiation effects to the fabrication of microoptical elements.

The synthesis of dihydrotetrathiafulvalene (DHTTF) donors and the preparation of their charge-transfer (CT) salts have been undertaken to develop new organic metals and superconductors. The molecular structures of methylenedithio-DHTTF (MDHT), 1,4-dioxane-2,3-diyldithio-DHTTF (DODHT), and methylmethylidenedithio-DHTTF (Me-MDHT) are secured by X-ray crystallographic analyses. These DHTTF donors provide CT salts characterized by a wide range of conducting behavior from semiconducting to metallic and superconducting. The crystal structures of CT salts from each category are described.

This study presents the effects of particle size on the monolayer structure of silica nanoparticles in the diameter range between 10 and 100 nm via a wet-coating process. Suspensions of silica nanoparticles coated on a solid substrate by a bar coater are dried to give a monolayer. For the comprehension of dominant factors in the formation process, the experimental results are compared with the results obtained by numerical simulations. Dense monolayers can be obtained in the diameter range of silica nanoparticles from 10 to 100 nm via the wet-coating process; however, the monolayers of the nanoparticles, the diameter of which is 11 nm, cannot be obtained at the coverage over 0.7. The pair correlation function of the monolayer shows that the 11-nm nanoparticles are arranged with the Inter-particle separation of about 1-2 nm. A feasible model for the formation process suggests that the hydration force between silica surfaces retains the nanoparticles with a constant separation.

Monolayers of well-ordered close-packed silica nanoparticles (NPs) with a diameter of 25 nm were spontaneously formed on silicon substrates over a large area and at a high rate via a wet-coating process using a capillary coater. The effects of zeta potential, dispersion solvent, and substrate friction on the NP self-assembly induced by the solvent evaporation were investigated. Experimental results showed that the solvent and the substrate had a larger impact on the order of formed monolayers than the zeta potential did, which are discussed from the viewpoint of the Derjaguin-Landau-Verwey-Overbeek (DLVO) and non-DLVO theories. Based on the above studies, we proposed a solution to fabrication of well-ordered NP monolayers without boundary defects at the surface coverage of ∼1 via the wet-coating process.

Supramolecular assemblages made of single wall carbon nanotubes (SWNT) filled with fullerenes or metal doped fullerenes exhibit promising electronic structure variations at a nanometer scale. Nevertheless, the knowledge about the structural defects of these systems is still very limited. Here, we report structural evolutions under high-resolution electron microscopic observation at the sensitivity of a single atom detection for Ca@C82 molecules encapsulated within SWNT.

This paper presents the effect of frictional force between colloidal particles and a solid substrate on the formation of particle monolayer by a numerical simulation. Discrete Element Method is employed to simulate the dynamics of colloidal particles trapped in a liquid film. Forces such as capillary immersion force, contact force, van der Waals force and frictional force are included in the simulation model. Isotropic ordering factor and non-dimensional boundary length are introduced to quantify the structures of colloidal particles. In the case where the diameter of colloidal particles ranges from 100nm to 1000nm, the monolayer structures depend strongly on the frictional constant between a particle and a solid substrate. On the other hand, in the case where the diameter is about 10nm, large domains of hexagonal close-packed structures are formed because of the Brownian force.