We developed a stage-scanning system for confocal scanning transmission electron microscopy (confocal STEM), which enables us to perform STEM under a fixed lens configuration without a beam-scanning system. A specimen holder with a piezo-driven stage was modified and controlled by a computer program for stage scanning. The signals of transmitted electrons detected by an STEM detector were displayed on a computer screen and were synchronized with the voltage supplied to the piezoelectric devices used for stage positioning, which consequently produced a stage-scanning STEM image. Furthermore, we evaluated the stability of the developed stage-scanning STEM system and the resolution of the obtained images. 0.2 nm lattice firings could be observed in Au particles, which indicated that this system could demonstrate atomic-resolution STEM imaging at desired z positions. This is attributed to the small specimen drift, stable stage scanning and the computer program developed for stage axis corrections. Finally, we applied this stage-scanning system to confocal imaging. [DOI: 10.1380/ejssnt.2008.111]

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Angle-resolved photoelectron spectroscopy and low-energy electron diffraction measurements have been carried out to characterize the Cu oxide overlayer formed on the Zn-terminated ZnO(0001) surface. Deposition of Cu and subsequent oxidation lead to Cu₂O with (111) orientation. The Cu₂O(111) lattice structure is expanded so as to realize the epitaxial relationship to the underlying ZnO surface. The valence-band maximum of the Cu₂O overlayer is found to be shifted to the lower-binding-energy side by ∼ 0.4 eV in comparison with that of bulk Cu₂O, suggesting a stronger p-character of the overlayer than the bulk material. [DOI: 10.1380/ejssnt.2008.226]

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Effects of CO adsorption on the magnetic properties of Fe films on Cu(001) were studied at 100 K as a function of the film thickness. CO adsorption does not affect the magnetic property of 2 ML Fe film but induces the spin reorientation transition from perpendicular to in-plane magnetization for 4 ML Fe film. It also causes the apparent decrease of magnetization, which is attributed to the reduction in surface magnetization by analyses of depth-resolved XMCD spectra. The reduction of the magnetization can be originated from a reconstruction of the surface structure of the films. It was suggested that the surface structures of the 4 ML Fe film are changed to a bcc-like structure upon CO adsorption, while the structure of the 2 ML Fe film could not change by CO adsorption because its magnetization is unchanged. [DOI: 10.1380/ejssnt.2008.233]

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Metal coordination polymers, such as cobalt-coordinated polypyrrole (CoPPy), have attracted much attention, because they are promising alternatives to oxygen reduction electrocatalysts for fuel cell applications, owing to their high oxygen reduction activity as well as corrosion protection performance. In this catalyst, incorporated cobalt acts as the catalytic active site for the catalytic reaction. Thus, if we can increase the number of active cobalt sites, the catalytic activity should increase. We demonstrated the improvement of catalytic activity of CoPPy, i.e., increase of cobalt sites, by the nano-scale structure control using appropriate counter-ion doping. We found that the inter-chain distance of PPy with dodecylbenzensulfonic acid (DBS) was significantly increased, up to 4.8 Å, while inter-chain distance of PPy with chloride ion was 3.4 Å. Also, the amount of cobalt on CoPPy-DBS was five times larger than that of CoPPy-Cl. This result indicates that the amount of the cobalt sites increase and consequently the catalytic activity is enhanced when the inter-chain distance increased by counter-ion doping. [DOI: 10.1380/ejssnt.2008.237]

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Structure-based drug design (SBDD) is one of the attractive and promising methods in drug discovery. In this study, we developed a software program predicting the binding site and the binding mode of ligands against a target protein for SBDD. The prediction method is based on the calculation of the hydrophobic potential energies around a target protein because the hydrophobic interaction is considered to be an important driving force in molecular recognition. Our program was tested with exemplifying 5 kinds of proteins, and was demonstrated to correctly predict the binding site and the binding mode of ligands seen in the experimentally determined structures for the protein-ligand complex. [DOI: 10.1380/ejssnt.2008.241]

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We investigated the magnetic anisotropy of bare and Pd-capped Fe ultra-thin films on the Pd(001) single crystal substrate using soft X-ray magnetic circular dichroism (XMCD) spectroscopy. XMCD spectra indicate that the spin reorientation transition (SRT) occurs in Fe/Pd(001). It is suggested that the SRT in Fe/Pd(001) is related to the film morphology. In Pd/Fe/Pd(001), in-plane magnetic anisotropy was observed. No evidence of perpendicular magnetic anisotropy was obtained, which is in contrast to the L1₀-ordered FePd alloy. [DOI: 10.1380/ejssnt.2008.246]

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We hereby report a growth mode and surface structure of ultrathin Cr films on fcc Fe/Cu(001). We have found a clear RHEED intensity oscillation during Cr deposition up to four monolayers on 3 and 6 ML Fe/Cu(001), indicating an layer-by-layer growth. Besides, the observed (2×1) LEED pattern at low Cr thickness is similar to that of fcc Fe/Cu(001) in the 5-11 ML thickness range. We have also demonstrated the Cr/Fe multilayer growth with single monolayer of Cr inserted between fcc Fe layers. [DOI: 10.1380/ejssnt.2008.251]

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We have determined the valence band discontinuities of InN/Mg:GaN and InN/Si:GaN heterostructures by hard x-ray photoemission spectroscopy. InN thin films were grown by pulsed laser deposition method and streaky high-energy electron diffraction pattern was observed, indicating that good crystalline InN films were grown. The value of valence band discontinuity for InN/Mg:GaN is as small as 0.3 eV, while that for InN/Si:GaN is 1.4 eV. The fact that the InN/Mg:GaN interface has the small energy barrier suggests that InN is very promising for the interlayer between transparent conductive layers and Mg:GaN in light emitting diode structures. [DOI: 10.1380/ejssnt.2008.254]

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Starting from a first principle many-body theory, we derive a general formula to describe overall features in core-level photoemission including plasmon losses and peak asymmetry due to X-ray singularity. In the high-energy region we can derive quantum Landau formula which is directly compared with the corresponding classical theory where electron propagation in solids is classically described. In this quantum Landau formula elastic scatterings before and after the loss is completely taken into account. The total photoemission intensity is factorized as (elastic part)×(inelastc part): For the latter we have a quantum Landau formula. Explicit numerical calculations are also shown for rather high energy region, 7-10 KeV from Al 2p level. Although the interference term should drop out as a function of photoelectron energy, we find that the rate is very slow. [DOI: 10.1380/ejssnt.2008.263]

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The stabilities and atomic geometries of the graphene adatom and its dimer are studied using first-principles calculations based on the density functional theory. In the most stable structure, the adatom is located above the bond-center site. We also found a metastable structure whose formation energy is slightly (0.25 eV) higher than the most stable structure. The diffusion barrier of the adatom is estimated to be 0.44 eV. Then, dimers are expected to be formed by the diffusion of the adatom. The dimer has three stable structures whose formation energies are close to each other. Since the dissociation energies of these structures are large (5.90-5.93 eV), the dimers are energetically stable. Therefore these structures are expected to be detected under some experimental conditions. [DOI: 10.1380/ejssnt.2008.269]

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We have studied the atomic structure of the surface and interface of VO₂/TiO₂(110) model catalyst by X-ray photoelectron diffraction (XPED). In this study, vanadium was deposited on the TiO₂(110) surface in the oxygen atmosphere. We characterized the VO₂ ultra-thin film grown on the TiO₂(110) surface by low energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), and XPED. As a result, VO₂ ultra-thin film grown epitaxially on TiO₂(110) was determined by using the multiple scattering cluster model with spherical wave (MSC-SW). Finally, we carried out the quantitative analysis by using the reliability factor R (R-factor) method and clarified the surface and interface structures of VO₂/TiO₂(110). [DOI: 10.1380/ejssnt.2008.272]

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We have studied the metal-insulator transition near room temperature on the Si(553)-Au surface with surface X-ray diffraction. Diffraction intensities due to the ×2 superstructure developing in the transition were collected at 86 K. The Patterson map calculated from the experimental intensities shows that only a few atoms are involved in the transition. The atoms are displaced mostly in the surface plane. The temperature dependence of the intensity and width of one reflection due to the low temperature superstructure was measured as well. The changes in the intensity of this reflection below the transition temperature are consistent with the predictions by the mean-field theory for a Peierls transition at 336 K. The changes of the intensity above the transition temperature and the temperature dependence of the width of the reflection can be explained by the influence of defects. [DOI: 10.1380/ejssnt.2008.281]

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By monitoring the post-growth behavior of surface bonded hydrogen on the Si films prepared from gas phase discharge of SiH₄, it is shown that thermal desorption of surface hydrogen from multi-hydride (SiH₂ and SiH₃) configurations obstructs crystal formation through a disruption of T_d symmetry in Si bonding. [DOI: 10.1380/ejssnt.2008.286]

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The initial adsorption process of Bi onto the Si(111)7×7 surface, including nanocluster formation, has been investigated by a real time structural analysis using in-situ RHEED intensity monitoring during the Bi adsorption, as a complementary approach to local and statistical structure analysis by STM. At an elevated temperature, the intensity distribution of 7×7 diffraction pattern varied gradually with the Bi adsorption and temporal intensity maxima which indicate the change of ad-layer symmetry without any serious disorder were observed. Subsequent STM observations clearly showed the formation of adsorption structure. From these results, multistep ordering process in Bi initial adsorption onto Si(111)7×7 was concluded, i.e. there are several coverage-dependent adsorption structures. Bi magic nanocluster was clearly observed by STM in atomic resolution. [DOI: 10.1380/ejssnt.2008.291]

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The authors studied the structure and dynamics of water monomer and dimer on Cu(110) by using a scanning tunneling microscope (STM) and density-functional theory (DFT). The monomer adsorbs on top of a Cu atom and thermally hops along the atomic row at 6 K. The hopping motion is also induced via inelastic electron tunneling process. The dimer consists of hydrogen-bond donor and acceptor molecules, that were observed to dynamically exchange their roles via hydrogen-bond rearrangement. The interchange motion was suppressed upon substitution with heavy water, suggesting that the process involves quantum tunneling. [DOI: 10.1380/ejssnt.2008.296]

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We performed an atomic-scale analysis of self-positioning nanostructures using the atomic-scale finite element method (AFEM) and Kriging interpolation technique. Equilibrium atomic configurations are determined for varying structure thicknesses and results are compared with the continuum mechanics solution under plane strain conditions. We observed significant decrease of the equilibrium curvature radius when the structure thickness is less than 40 nm. It is found that large compressive strains near the free surface affect the distribution of strains as the structure size decreases. [DOI: 10.1380/ejssnt.2008.301]

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Molecular dynamics simulations are presented for the angular collisions of 561-atom icosahedral cluster on a weakly attractive substrate. We study the effect of rotational motion of the cluster at various impact velocities and incident angles. The outcome of the collision is determined by incident kinetic energy of the cluster and the cluster-surface adhesion energy. Energy losses are greater when the collisions of the cluster with initial angular velocity are considered. At larger impact angles, the cluster loses a relatively larger amount of rotational kinetic energy by the collision. The transition from reflection to adhesion is observed at high initial angular velocities due to increase in the rotational kinetic energy and plastic deformation of the cluster. [DOI: 10.1380/ejssnt.2008.307]

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