The energy dissipation in non-contact atomic force microscopy (NC-AFM) caused by the hysteresis loop of the potential energy between a tip and a sample with respect to the tip height is investigated in detail by the case studies for models of a graphite flake with a diamond tip. One of the models is made up of a graphite flake on a graphite surface. In this case, the hysteresis is caused by the difference of the lateral positions of the flake during the upward and the downward motion of the tip. The other model is made up of a graphite flake edge. In this model, the hysteresis is caused by the difference of the vertical positions of the flake edge during the upward and the downward motion of the tip. [DOI: 10.1380/ejssnt.2008.1]

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We compared fluctuations of electron beams emitted from single-atom electron sources, on which the surface Pd metals were deposited by two different techniques, vacuum deposition and electroplating deposition. The similar nano-pyramids were fabricated successfully by both the techniques, but the stabilities of the beam currents were different each other; the electron source prepared by vacuum deposition was far superior to those of electroplating deposition. The possible origin was discussed on the basis of AES analysis. [DOI: 10.1380/ejssnt.2008.11]

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We have performed molecular mechanics study of nanoscale peeling and adhesion processes of carbon nanotube (CNT) on the rigid graphite surface. First, as a model of CNT, single-walled carbon nanotube (SW-CNT) of the (3,3) armchair type with a length of l=99.3 Å comprised of 480 carbon atoms is used. In the simulation CNT physically adsorbed on the graphite substrate is peeled (retracted) from the surface and then adsorbed (approached) onto the surface. We have first obtained the vertical force-distance curve with the characteristic hysteresis loop derived from the bistable states between the line- and point-contacts during the peeling and adhesion processes. The analysis of the vertical and lateral force curves reveals that the CNT shows multiscale mechanics - both nanoscale mechanics on the order of CNT's length (≈ 100 Å) and atomic-scale mechanics on the order of CNT's diameter (≈ several Å). The deflection of CNT along z direction for some regions can be well explained by theory of elasticity. Next the effect of the CNT length l on the peeling process is studied. As the CNT becomes shorter, discrete jump of the force curve vanishes and the peeling force curve exhibits continuous behavior because the shorter CNT has larger spring constant k_z along the vertical direction. The length l dependence of k_z in the present simulation exhibits k_z ∝ l^-2.98, which is in good agreement with theory of elasticity, k_z ∝ l ^-3. Lastly the effect of the chirarity of the CNT on the peeling and adhesion processes is studied for the armchair, zigzag and chiral type CNTs for the length of about 50 Å. The hysteresis of the peeling curve shows the slight difference of the adhesive behavior among different chirality of CNTs. [DOI: 10.1380/ejssnt.2008.72]

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Transparent thin films of α-Fe₂O₃ have been deposited on glass substrates by chemical spray pyrolysis (CSP) technique using solution of aqueous iron (III) nitrate at 300-450°C. Their structural, optical, and electrical properties were investigated without post-deposition annealing. XRD data confirm that the grown film at 450°C was polycrystalline in nature and has preferred orientation in (110) direction while films grown at lower temperatures were amorphous. The film exhibits high average optical transmission (80%). The optical data revealed that the optical indirect and direct band gap energies of films were 1.9 eV and 2.68 eV respectively. Electrical measurements show that the deposited α-Fe₂O₃ film is n-type and the electrical resistivity of the film was about 2.5 × 10⁴ Ωcm. [DOI: 10.1380/ejssnt.2008.96]

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The crystal structure of manganese nitride material depends on the chemical composition. In this paper, we report the crystal structure of manganese nitride which depends on the deposition condition of a flow ratio of argon and nitrogen, F_N{=N₂/(Ar+N₂)}. The samples were fabricated by an RF-sputtering method. Argon and nitrogen were used as a reactive sputtering gas. The crystal structure of the obtained films was analyzed by X-ray diffraction (XRD) measurements. The stoichiometry of the film under F_N=5-100 % was evaluated as Mn₃N₂. The lattice spacing d of (101) expands as the nitrogen flow ratio increases. In the case of F_N=1 %, the composition was evaluated as Mn₄N. [DOI: 10.1380/ejssnt.2008.115]

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Molecular resolution scanning tunneling microscope (STM) images the spontaneous self-assembly of 11-ferrocenyl-1-undecanethiol ((C₅H₅)Fe(C₅H₄)(CH₂)₁₁-SH) forming a large striped-phase on highly oriented pyrolitic graphite (HOPG) at a phenyloctane-HOPG interface. In the image, the alkyl chains lying flat on HOPG appear as bundles in groups of five in the moiré pattern due to lattice mismatch with the underlying HOPG. The ferrocene units appearing as either fuzzy or ring-like structures suggest the random rotation of cyclopentadienyl (Cp) rings sandwiching the central iron ion of the ferrocene moieties with their principal axis either oblique or perpendicular to the HOPG. The ferrocene moieties are more clearly resolved in a mixed film with octanethiol, where the fuzzy or ring-like structures of the ferrocene units are asymmetrically distant from the sulfur head-groups forming alternating rows in the phase segregated image. Both molecules can be clearly distinguished by the length of the molecular rows. [DOI: 10.1380/ejssnt.2008.119]

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The effect of hydrogenated amorphous silicon (a-Si:H) intrinsic layers, deposited on boron-doped multicrystalline silicon (mc-Si) wafers at various deposition temperatures, on heterojunction solar cells prepared using the radio-frequency remote PECVD method are investigated. The structural and optical properties of the a-Si:H films formed at various deposition temperatures that ranged from 50 to 400°C changed with increasing temperature. The effective carrier lifetimes of the mc-Si wafers with the a-Si:H films increased with increasing deposition temperature to a maximum of 250°C. Furthermore, the wafers passivated with the a-Si:H films deposited temperatures below 250°C, and the effective carrier lifetime drastically improved to about 2-5 times its as-deposited value and over the chemical passivation lifetime after annealing treatment at 350°C. It was found that a combination of a-Si:H film deposition and annealing treatment provides excellent bulk passivation. [DOI: 10.1380/ejssnt.2008.124]

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We have developed a practical method to produce durable artificial lipid bilayers using a hydrogel-hydrogel interface for ion channel measurements. Bilayers were formed by forcing a hydrogel-bead into contact with the hydrogel layer (hydrogel plate) in a lipid solution. The immediate formation of a bilayer was observed (<1 s). This allows channel recordings to be repeated more easily and quickly as compared to conventional methods. Currents of various types of channel such as gramicidin, hemolysin and BK-channel have been recorded. Our channel property results mirrored those of other techniques and were reproducible. Hydrogel solutions containing gramicidin were extremely stable and could be used months after preparation for bilayer experiments. [DOI: 10.1380/ejssnt.2008.130]

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We developed a new quantitative detection method for an immunoreaction combining magnetite (Fe₃O₄) nanoparticle labeling with confocal Raman spectrometry. Magnetite nanoparticles are transparent, Raman active, and easily can be controlled easily by magnets in bimolecular reactions. Human Chorionic Gonadtropin (hCG) was selected as a target molecule for this investigation. Sandwich immunoreaction was performed on a dot-patterned substrate using two anti-hCG antibodies, which were the antibody immobilized on the substrate and the biotinylated antibody. The immunoreaction was microscopically visualized by reacting streptavidin-modified magnetite nanoparticles with the biotinylated antibody on the substrate. The adsorbed magnetite nanoparticles on the dot pattern were detected by Raman intensity imaging. A good linear relation between the integrated Raman intensity spectra at 220 cm^-1 and hCG concentration was gained. This method may be applied toward the detection of other target molecules in the fields of biotechnology and biomedicine. [DOI: 10.1380/ejssnt.2008.142]

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We have observed porous alumina layers fabricated by the anodic oxidation of aluminum sheets utilizing a selective etching. We have found that two types of 3-dimensional structures form inside the alumina layer during the oxidation process. One is dome-like micro-structures which have straight pores of approximately 100 nm in diameter, and the other tree's root-like structures which grew in a radial manner. By using non-uniform etching conditions that the concentration of phosphoric acid is more than 20 wt%, those buried structures appear because the matrix is preferentially removed. Moreover, we have found that the position of the dome-like structures can be controlled by artificial scratches on the initial surface. [DOI: 10.1380/ejssnt.2008.147]

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Field emission properties were studied for tips sharpened using field-assisted nitrogen and oxygen etching. Sharp single crystal tungsten <111>-oriented tips were fabricated and evaluated by Fowler-Nordheim plots and field-ion microscopy observations. The results demonstrated emissions at lower bias voltages due to the sharpening of the tip apex using the etching. The field emission properties and tip shapes after nitrogen etching were compared with those obtained after oxygen etching. [DOI: 10.1380/ejssnt.2008.152]

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The spin-dependent electron transport properties of a metallic (5,5) single-walled carbon nanotube with either carbon (C) or boron (B) adatoms were investigated using a non-equilibrium Green's function technique combined with spin-dependent density functional theory. We find that both of the non-magnetic B and C adatoms cause zero-bias conductance that is highly dependent on the spin states of the conduction electrons. The microscopic origin of this phenomenon is explained by the features of the spin-dependent local density of states in the region of the adatom. From the present calculation it was also determined that the spin-dependent conductance is controllable by tuning the applied gate voltage, which would be a useful property for application in spin filters. [DOI: 10.1380/ejssnt.2008.157]

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It was found that mesoscale patterned films of titanium dioxide nanocrystals have superior photocatalytic activity as compared to unstructured films. The nanocrystals were adsorbed onto surface-functionalized and crosslinked polymer honeycomb films. After calcination, the porous structure remained and photocatalytic activity was evaluated by the photolytic decomposition of a cyanine dye in aqueous solution. [DOI: 10.1380/ejssnt.2008.161]

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The arc discharge method was the first method developed for producing multiwalled carbon nanotubes (MWNTs). Generally, this method is carried out in low-pressure He gas or other neutral atmospheres, which requires the use of sealed reaction chambers and vacuum equipment. At high temperatures, the method produces well-graphitized MWNTs. Here, we report the first successful trial of the facile synthesis of high-quality MWNTs in a high yield using the arc discharge method in foam. [DOI: 10.1380/ejssnt.2008.167]

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Si nanochains have been prepared via a simple hydrothermal deposition route using silicon monoxide as the starting material at 300°C. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectrum (EDS) and high-resolution transmission electron microscopy (HRTEM) are used to observe the structure and morphology of the products. The obtained Si nanochains are composed of knots and necks with polycrystalline silicon cubic structure. The surface of the Si nanochains is covered with amorphous silica outer layers. The growth mechanism of the Si nanochains is discussed. [DOI: 10.1380/ejssnt.2008.171]

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A thin conductive polymer recording medium with angstrom-scale surface roughness has been formed on template-stripped gold (TSG) surface by surface-graft polymerization for scanning multiprobe data storage. A gold film is deposited on a mica plate, which is bonded onto the silicon substrate with a gold film using gold-gold direct bonding technique. By removing the mica plate, gold surface with the angstrom-scale surface roughness is formed. A conductive polymer film as a recording medium is deposited on the TSG surface by the surface-graft polymerization. As a result, the polymer film with small roughness is obtained. Thus, the use of the TSG surface is efficient way to form the flat conductive polymer film. Finally, reversible electrical modification on the polymer film is demonstrated using atomic force microscopy. These results show the possibility that this formation method of the conductive polymer film provides rewritable recording media with small roughness for scanning multiprobe high-density data storage. [DOI: 10.1380/ejssnt.2008.202]

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Valence and conduction states near the SiO₂/Si(100) interface were directly observed using soft x-ray absorption and emission spectroscopy. For the O K-edge absorption spectra, the step-like structures were observed at 531, 533 and 534.5 eV. These step-like structures observed at 531, 533 and 534.5 eV were assigned to an oxygen atom bonding to Si¹⁺, Si²⁺, and Si³⁺ of the interface, respectively. In the case of O K-edge emission spectra, with decreasing incident photon energy from 535 to 531 eV so as to shift the conduction band minimum of the interface towards Fermi energy, the corresponding valence band maximum was shifted to Fermi energy direction. Thus, the local band gap became narrower with the decrease of the oxidation number of the suboxide species. Further the interface structure was also discussed from the spectrum features. [DOI: 10.1380/ejssnt.2008.209]

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Transient current behavior through a nanoscale system responding to a sudden voltage application was investigated, based on the Liouville equation of density matrix. It was found that the transient current behavior is characterized with the oscillation and relaxation processes. The oscillation originates from the time-dependent electron transitions between the electrode and nanoscale system, and the period depends on the Fermi energy and the bandwidth of electrodes. On the other hand, the relaxation occurs due to the energy dissipation into a number of electronic states in electrodes, thus, the relaxation time depends on the density of states in electrode and the electron transfer energy between the electrode and nanoscale system. Furthermore, we clarified that the strong electron-electron interaction decreases the relaxation time. [DOI: 10.1380/ejssnt.2008.213]

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The transfer of a polymeric micropattern onto a poly(methyl methacrylate) film surface was achieved by the pulsed laser irradiation of Coumarin 6 molecules using self-organized polymer honeycomb templates. The molecular implanted areas were analyzed by fluorescence microscopy and fluorescence spectroscopy. It was found that the implantation patterns were affected by the configuration of the sample, the template, and the atmospheric conditions. This technique is applicable to the production of molecular patterns on a centimeter-scale region of polymer film surfaces by a simple process. [DOI: 10.1380/ejssnt.2008.222]

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Average grain size, microstrain and anisotropy factor of dislocation have been estimated from x-ray diffraction patterns of as-produced, annealed and oxidized nickel coated carbon fibers, using modified Williamson and Hall method. The results show a high anisotropy due to diffraction line broadening for both as-received and annealed specimen. Air oxidized fibers show nearly no anisotropy. The anisotropic strain broadening of diffraction profiles was accounted for by dislocation contrast factors. The screw or edge character of dislocations was determined by analysing the dislocation contrast factors. Heat treated specimen at 500°C are formed only by graphite and nickel, while after oxidation, only NiO with cubic (NaCl type) structure (a = 0.417nm), and average grain size about 30nm, is present with graphite. A novel finding that a transparent nickel oxide film can be obtained when a composite material consisting of nickel and carbon is heat-oxidized in air according to a simple treatment involving a heat oxidation temperature of 500°C and a heat oxidation time of 60 minutes. [DOI: 10.1380/ejssnt.2008.258]

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Thin MnSi films growing by units of a quadruple layer of a B20-type structure are observed on the Si(111) surface by scanning tunneling microscopy. Based on the observation, a model of growth controlled by an interplay between MnSi crystal growth and supply of Si atoms from substrate is proposed. A simple Monte Carlo model efficiently simulating significant experimentally observed features is presented. [DOI: 10.1380/ejssnt.2008.276]

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Laser irradiation of Copper phthalocyanine tetrasulfonate (CuPcTs) microcrystals in some poor solvents has produced CuPcTs nanoparticles with 15-112 nm in diameter. Field emission scanning electron microscopy (FESEM) images have shown densely packed nanoparticles of CuPcTs formed in methanol and acetone. The mean diameter of CuPcTs nanoparticles obtained from TEM images in methanol, 2-methy-2-propanol, ethanol, tetrahydrofuran, and acetone were determined to be 26, 36, 35, 86, and 78 nm, respectively. The size and surface morphology of CuPcTs nanoparticles have been correlated with solvent parameters such as polarity and thermal diffusivity. [DOI: 10.1380/ejssnt.2008.312]

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New transparent and electric conductive material, Mg(OH)₂-C, was prepared by the sputtering Mg and C, and post-reaction of the Mg-C film with moisture in the air. The prepared film was composed of Mg, C, O, and H, and the lattice symmetry was identified to be Mg(OH)₂ structure (P-3m1) with slightly elongated c-axis compared with hexagonal Mg(OH)₂. The transmittance of the visible ray was 90% in the average. The electric resistivity of the film was on the order of 10^-1Ωcm. [DOI: 10.1380/ejssnt.2008.15]

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Low voltage electron emission from ferroelectric thin films consisting of BaTiO₃ is reported. The 1 μm thick BaTiO₃ thin films were deposited by spin coating and were annealed to improve their crystallinity. Then surface treatments using hydrochloric acid have been performed and very thin gold top electrodes were deposited. The electron emission capability of these thin films has been tested using a parallel cathode-positively biased anode arrangement in a vacuum chamber at 10^-5 Pa. The turn on electric field for electron emission was 23 V/μm and we obtained an emission charge of about 200 pC/cycle at an electric field of 100 V/μm. [DOI: 10.1380/ejssnt.2008.164]

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We demonstrated super-resolution microscopy using a high numerical aperture (NA) oil immersion lens in acute optical alignment condition. In super-resolution microscopy, the pump beam is overlapped together with a doughnut-shaped erase beam in the focal plane, and fluorescence emission from the overlapping area is prevented. Alignment accuracy of these two beams determines the image properties of the microscope. Scanning fluorescence micro-beads in the focal plane, we confirmed the beam shape and its center position for the pump and erase beams respectively. Owing to the adjustment, we achieved a point-spread function with FWHM finer than 100 nm at least, which is predicted by the theory of super-resolution microscopy. [DOI: 10.1380/ejssnt.2008.175]

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Measurements of rotational and vibrational energies of desorbing products in chemical reactions provide useful information on dynamical processes of bond formation and bond rupture and also on structures of transition states. In order to obtain structural information, dependence of these energies on the desorption angle of products should be studied. However, such angle-resolved (AR) measurements of internal energies in thermal surface reactions have long time been lacking due to difficulty of experiments. Recently, measurements of internal energies of AR product CO₂ in CO oxidation on Pd surfaces have become possible by detecting extremely weak infrared chemiluminescence from desorbing CO₂. Rotational and vibrational energies change depending on polar and azimuth angles and also surface structures, providing new insights into structures of transition states and energy partition dynamics. In this review, recent progress in the above AR measurements is described. [DOI: 10.1380/ejssnt.2008.180]

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In this review, recent findings on growth manners, quantum confinement phenomena, and carrier transport mechanisms of self-assembled Ge nanodots on an oxidized Si surface are summarized. A simple equation relating the dot size, which was estimated by STM images, with the Ge coverage was proposed. Quantum confinement was observed by photoemission spectroscopy (PES) and scanning tunneling spectroscopy (STS), and the actual height of the confining potential was determined from the dot-size vs. energy relationship through a three dimensional parabolic potential model. The transport mechanism of the nanodot arrays, which was estimated based on the measurements by a microscopic four-point-probe method, was distinct depending on the structure of the dot-substrate interface. All results suggest that the interface oxide layer and subnanometer-sized voids on it interconnecting the nanodots with the substrate not only regulate the quantized energy in the nanodots but also switch on/off carrier exchange between the nanodot and the substrate through variable interface potential barrier height. [DOI: 10.1380/ejssnt.2008.191]

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A way of nuclear spin manipulation using an interface of diluted magnetic semiconductors (DMSs) is proposed. The hyperfine field at an impurity site in the interface of a DMS and a base substance can be controlled by applying the external electric field. It is because that the electric field changes the spin density of carriers in the s state at the impurity site. On the basis of first-principles electronic structure calculation, we investigated the electric-field dependence of the hyperfine field at the impurity site. We show that the hyperfine field is dramatically changed by an external electric field when no clear magnetic impurity band is formed in the band gap. [DOI: 10.1380/ejssnt.2008.7]

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We proposed the stabilization of cholesteric blue phases (BPs) by confining liquid crystal (LC) molecules within a small area. The temperature range of the BP was expanded in the LC confined in the polymer network (PN). In particular, the temperature range of BP I in the LC/PN composite is six times wider than that of the pure BP LC compound. Polarizing microscopic observations and field-dependence measurements of the expanded BP have been carried out, which indicate that it is in the metastable state and is induced by the pinning effect on the surfaces of the PN. [DOI: 10.1380/ejssnt.2008.17]

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We report a series of our experiments using organic single crystals to reach the maximum performance intrinsic to the materials. A consequence of the experiments is that a good prescription for realizing high-mobility devices is to induce carriers in inner crystals to avoid scattering at the surfaces. Intrinsic-semiconductor character of the high-purity organic crystals favors thermal diffusion of the carriers into the crystals in the presence of weak gate-electric fields. [DOI: 10.1380/ejssnt.2008.21]

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Using noncontact atomic force microscopy (NC-AFM), we analyzed the height distribution of individual atoms by atomically resolved topography of Pb/Si(111)-(√3 × √3) mosaic phase surfaces, discriminated Pb, and substituted Si adatoms atom-by-atom. This successfully revealed the atom-by-atom chemical coordination effect in the height distribution of individual atoms. We found that increasing the number of surrounding nearest-neighbor Si adatoms increases the height of Si adatoms but rapidly decreases the height of Pb adatoms. These coordination effects were qualitatively independent of the tip-sample surface distance. This result agreed with previous results on Sn/Si(111)-(√3 × √3) mosaic phase for only Si adatoms. Pb adatoms, however, showed a strong but opposite dependence on the number of surrounding Si adatoms, and the Sn adatom proved independent of the number of surrounding Si adatoms. Such differences in the chemical coordination in NC-AFM height distribution among the fourth period elements of Si, Sn, and Pb atoms will disclose to differences in charge transfer and related phenomena between intermixed heterogeneous atoms, due to differences in electronegativity and/or their metallic nature. [DOI: 10.1380/ejssnt.2008.79]

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We have studied the effect of the electric field on the adsorption structures of methylthiolate(MeS) on the Au(111) surface by using density functional theory. MeS has the bridge, fcc-hollow and ontop adsorption configurations and the relative stability among those configurations can be changed by applying the electric field perpendicular to the surface. The energy difference between the bridge and fcc-hollow configurations can be well described by a simple dipole-field interaction model and the relative stability is reversed at an electric field of about 26 V/nm. As for the energy difference between the bridge and ontop configurations, the effect of polarization becomes large at strong electric field. [DOI: 10.1380/ejssnt.2008.99]

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We have reinvestigated the method to determine the work function of metals by the first-principles electronic structure calculation using the plane-wave expansion method with pseudo-potentials. Changing width of a vacuum layer of a slab model, we obtained the Fermi level measured from the effective Kohn-Sham potential at the center of the vacuum layer. By extrapolating the values of the Fermi level to the infinite vacuum-layer limit, the Fermi energy is determined. We propose a fitting function for the extrapolation. This function works well for determination of the highest occupied level and the lowest unoccupied level of materials with a surface relative to the vacuum level in the Kohn-Sham scheme. The obtained work functions for [100], [110] and [111] surfaces of three noble metals, Rh, Pd and Pt are comparable to the known theoretical estimation as well as the experimental values. [DOI: 10.1380/ejssnt.2008.103]

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We determine the effects of having vacancies on the Pt(111) surface to the dissociative adsorption behavior of H₂ on Pt(111). We study the potential energy behaviors along the reaction paths based on the potential energy surfaces (PESs) we calculated that are relevant to these systems. By comparing these results to those of an ideal Pt(111) surface, we find that the vacant sites enhance the surface reactivity by lowering the activation barriers for H₂ dissociative adsorption, as shown by several new reactions paths we observed corresponding to near spontaneous reactions. The results also corroborates our earlier findings that of the substrate atoms, the surface (first-layer) atoms mainly influence the behavior of H₂ adsorption on Pt(111), and that the onset of H₂ dissociation and barrier location are also altered by the presence of vacancies. [DOI: 10.1380/ejssnt.2008.134]

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This article was retracted.

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We have investigated emission properties of Au-covered W<111> nanotips fabricated by means of an electroplating method. The stable nanotips possessed a three-sided pyramid structure terminated with three atoms, differing from the nanotips covered with the other noble metals such as Pd, Pt, Rh, and Ir, of which all the final structures are terminated with a single atom. The observed values of the Au-covered nanotips were comparable with those of single-atom tips covered with the other noble metals; they were the semi-cone angle of 2 degrees, the brightness of 5 × 10⁸ A/cm²sr, and the half maximum full-widths of spectra, 0.3 eV. In addition, the self-repairing function and the demountable characteristic have been confirmed. As compared with other metal-covered nanotips, the other different feature of the Au-covered nanotips was their high reproducibility of the energy spectra. The hump always appeared at about 0.7 eV below Fermi level. [DOI: 10.1380/ejssnt.2008.25]

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To observe the dynamical behavior of superconducting vortices and the motion of domain structure in magnetic materials by transmission electron microscopy (TEM), it is important that the direction of an external magnetic field applied to the specimen can be adjusted appropriately as well as the electro-optical axis, the crystalline orientation and morphological orientation of the specimens. Direction-free magnetic field application system that has three coil-pairs for generating and controlling the external magnetic field in any direction was developed to achieve the purpose. The system also has twenty-four coils to compensate the deflected electron beam by the external magnetic field applied. The system has been installed in the 1-MV and 300-kV field emission electron microscopes to utilize application research works. [DOI: 10.1380/ejssnt.2008.29]

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The secondary electron (SE) images were recorded for Si wafers with and without SiO₂ thin (10 nm-50 nm) films by a scanning electron microscope (SEM) with changing primary electron energy from 2.5 keV down to 0.2 keV during one frame scan. Brightness of the SE image increased up to critical values and then decreased with decreasing primary electron energy for the specimens with SiO₂ films. The critical voltage is higher for specimen with thicker film. These results are discussed by means of the oxide film thickness, the penetration depth of incident electrons, and the surface potential caused by charging. [DOI: 10.1380/ejssnt.2008.35]

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Analyses of small-angle X-ray scattering (SAXS) and extended X-ray absorption fine structure (EXAFS) were performed for characterizing precipitates formed in a Cu-Ni-Si alloy without and with a small amount of Fe, the strength and electrical conductivity of which were improved by aging process. These alloy samples were aged at 720 K after a solution treatment. The SAXS profiles of the samples were measured to investigate the size of precipitates. The results of SAXS measurements showed that nanometer-size precipitates formed in the alloy samples during isothermal aging. The precipitates in the Cu-alloy sample without Fe appeared to be coarsened in a multi-modal size distribution by the aging process. In contrast, the precipitates with homogeneous size were formed for the Cu-alloy sample with Fe. The environmental structure of Ni and Fe of these alloys evaluated by EXAFS measurements revealed that the precipitates of these alloys have the structure of δ-Ni₂Si, and Fe substitutes Ni in δ-Ni₂Si. It is presumed that the precipitates of homogeneous size in the Fe-added Cu alloy were formed because highly dispersed Fe atoms serve as nucleation sites of Ni₂Si. [DOI: 10.1380/ejssnt.2008.38]

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In this study, graphite nanofibers (GNF) were analyzed by using the scanning atom probe (SAP) [1]. Graphite nanofibers (GNF) were grown on a SUS304 needle by the thermal CVD method. The SUS needle was mounted in the SAP and mass analyzed by applying DC and pulsed voltages to the specimen at room temperature. The field emission characteristics were also examined by operating the SAP as a field emission microscope. At the beginning of the mass analysis of GNF, small mass ions (< 100 amu) which could be ascribed to not fully decomposed precursor gas were detected. No significant mass peaks were detected in the mass range m/n = 100-200. After the removal of the surface layer, the detection rate of the clusters with the mass larger than 200 amu increased.
The evaporation voltage of GNF is found to be significantly lower than the voltage expected from its field emission characteristics. The largest mass peak was C₂₃H₂⁺ in the range of m/n = 200-300. The C₂₃H₂⁺ mass peak had a tail due to the weak C-H bond of the clusters. Other noticeable peaks were C₁₈H₇⁺, C₂₂H₂⁺, C₂₂⁺, and C₂₀⁺. [DOI: 10.1380/ejssnt.2008.41]

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We have studied surface morphology and surface reconstruction of an Al adsorbed Si(113) surface using a scanning tunneling microscope. A clean Si(113) surface is atomically flat, but well-ordered one-dimensional (1D) nano-facet structures with their width of about 2.5 nm are formed on this surface after 1 ML of Al deposition. In the faceting process, the initial stage is Al atoms replacement with Si atoms at 0.4 ML of Al deposition. Replaced Si atoms stick to steps, causing the change of steps shape. These Si atoms also form two-dimensional (2D) islands. The next stage is growth of 2D islands toward [-3-32] direction at 0.6 ML of Al deposition. At this coverage, 2D islands consist of (-961), (6-91), and (33-2) steps. For further Al deposition, (-961) and (6-91) steps become unstable and (33-2) and (-3-32) steps become stable. Finally, (33-2) and (-3-32) steps change into two kinds of nano-facet structures, i.e. (112) and (115) facets. On the (112) facet, a mixture of N × 1 structures (N = 3-8) is observed. The most abundant value of N is 6, which well agrees with the first principle calculation. While on the (115) facet, 4 × 1 structures are observed. [DOI: 10.1380/ejssnt.2008.45]

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Quantitative X-ray structural analysis is used for characterizing the atomic-scale structure of γ-FeOOH particles; these particles are formed by immersing pure iron, iron-aluminum, iron-silicon, and iron-phosphorus alloys into an aqueous solution of sodium chloride. The morphology of these γ-FeOOH particles is observed by transmission electron microscopy, and their bonding structure is analyzed using Fourier transform infrared spectroscopy. The realistic atomic-scale structure of the γ-FeOOH particles is estimated by fitting the interference functions with the help of the reverse Monte Carlo simulation technique. The results show that the linkages of fundamental FeO₆ octahedral units in γ-FeOOH had underwent deviation from the ideal crystal structure. The structural deviation and morphological change of the particles were considered to be due to the incorporation of foreign ions during the formation of these particles in the aqueous solution. [DOI: 10.1380/ejssnt.2008.49]

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Total electron emission yields have been measured for the first time resulting from impact of slow highly charged Ar^q+ (q ≤ 17), Xe^q+ (q ≤ 50) and Hg^q+ (q ≤ 68) ions on clean insulating LiF(001) and CaF₂(111) surfaces at various impact angles. The surprisingly large yields show that even for the highest projectile charge states, a local charge-up of the surface poses no barrier for electron emission. We demonstrate that this is due to a strong sub-surface contribution in the potential electron emission process which is considerably more efficient in insulators because of the increased inelastic mean free path and the production of secondary electrons. [DOI: 10.1380/ejssnt.2008.54]

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The EXAFS analysis of ferric oxide particles precipitated from ferric aqueous solutions including chloride ion and with/without additional anions such as sulfate or silicate. In the solution reaction process, an akaganeite (β-FeOOH)-like oxyhydroxide with low crystallinity is precipitated and subsequently transforms to hematite (α-Fe₂O₃). Coexistence of anion species of sulfate or silicate is effective to reduce the rate of structural transformation and influence morphology of final iron oxide products. The radial distribution functions was obtained by Fourier transformation from EXAFS spectra measured at Fe K absorption edge, and Debye-Waller factor related to Fe-Fe correlation was determined. The results indicated that the linkages with face-sharing and double-corner-sharing were influenced by adding anions in corrosion reaction solutions. [DOI: 10.1380/ejssnt.2008.60]

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We report the result of the noise measurement using an extreme high vacuum field emission microscope (XHV-FEM) operating under ∼ 7 × 10^-10Pa. The fluctuation of a field emission (FE) current for a clean W(111) tip was comparable to the corresponding shot noise fluctuation, demonstrating the suitability of the XHV-FEM for investigation on the inherent fluctuation behavior of the FE process. Semilogarithmic damping curves of FE currents were linear for more than 10 hours. The noise of field emission (FE) currents ranging from 10 pA to 100 μA was measured under ∼ 7 × 10^-10Pa. The lowest frequency measurement of shot noise was recorded at below 10 Hz. [DOI: 10.1380/ejssnt.2008.64]

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For developing electron microscopes mounted with a single-atom electron source, we constructed a practical gun chamber of an extreme high vacuum (XHV), and demonstrated excellent characteristics of its emission beams; the stable beam with the current fluctuation of ∼0.8 % was observed at the total current of 20 nA in the XHV of 1 × 10^-9 Pa. [DOI: 10.1380/ejssnt.2008.68]

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Reflection high energy electron diffraction (RHEED) patterns from the Si(111)√21 × √21-(Ag,Au) surface are analyzed by kinematical calculations. The models including three, four, and five gold atoms in a unit cell are examined for the structural analysis. The best model is concluded that the surface atomic structure includes three gold atoms in the unit cell. [DOI: 10.1380/ejssnt.2008.84]

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Energy filtered reflection high-energy electron diffraction (RHEED) patterns are analyzed for the Si(111)7×7 surface using full dynamical calculation. Calculated RHEED patterns of the Si (111)7×7 are not in agreement with measured ones for various surface atomic positions. Especially the calculated intensity ratio of the (1/7 1/7) and the (2/7 2/7) rods is very small in comparison with measured one. The discrepancy between measured and calculated RHEED patterns is not recovered for the filtered RHEED patterns using the theoretical real and imaginary potentials. It is found that the RHEED intensity ratio of the (1/7 1/7) and the (2/7 2/7) rods depends strongly upon adatom potentials. [DOI: 10.1380/ejssnt.2008.87]

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The space charge effects in a thermionic emission gun using a tungsten point cathode have been studied with numerical method. The method is based on the integral form of Poisson equation, where the space charges are treated with a large number of coaxial charged rings surrounding the cathode. Each ring charge is estimated from many electron trajectories traced in 3D. The distribution of the space charge density around the cathode of the tip radius 0.4 μm was calculated for different bias conditions and different cathode temperatures. The space charge effects were examined by comparing these distributions as well as the axial potential and field distributions near the tip. The numerical results show that even at the temperature as high as 3100 K the cathode can provide the emission without any noticeable space charge effects when the negative bias on the Wehnelt electrode is shifted by several volts from the cutoff. [DOI: 10.1380/ejssnt.2008.91]

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Low-energy electron microscopy (LEEM) has been used to measure reflectivity of low-energy electrons for graphene layers grown on Si-terminated 6H-SiC(0001) and 4H-SiC(0001) substrates and C-terminated 4H-SiC(000-1) substrates. We observe quantized oscillations in the reflectivity on all the substrates. The number of graphene layers grown on both the Si-terminated and C-terminated substrates can be determined microscopically as the number of dips in the reflectivity between 0 and 7 eV. We also find that the dips appear closer to the vacuum level on the C-terminated substrates than on the Si-terminated substrates. This could be explained by the differences in the work function and Fermi level position between the graphene layers grown on the Si-terminated and C-terminated substrates. [DOI: 10.1380/ejssnt.2008.107]

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