-
Atsushi Hatakeyama, Markus Wilde, Katsuyuki Fukutani
Article type: Regular Paper
Subject area: Reaction and Dynamics
2006 Volume 4 Pages
63-68
Published: 2006
Released on J-STAGE: January 12, 2006
JOURNAL
FREE ACCESS
We attempt to provide physical interpretations of light-induced desorption phenomena that have recently been observed for alkali atoms on glass surfaces of alkali vapor cells used in atomic physics experiments. We find that the observed desorption phenomena are closely related to recent studies in surface science, and can probably be understood in the context of these results. If classified in terms of the photon-energy dependence, the coverage and the bonding state of the alkali adsorbates, the phenomena fall into two categories: It appears very likely that the neutralization of isolated ionic adsorbates by photo-excited electron transfer from the substrate is the origin of the desorption induced by ultraviolet light in ultrahigh vacuum cells. The desorption observed in low temperature cells, on the other hand, which is resonantly dependent on photon energy in the visible light range, is quite similar to light-induced desorption stimulated by localized electronic excitation on metallic aggregates. More detailed studies of light-induced desorption events from surfaces well characterized with respect to alkali coverage-dependent ionicity and aggregate morphology appear highly desirable for the development of more efficient alkali atom sources suitable to improve a variety of atomic physics experiments. [DOI: 10.1380/ejssnt.2006.63]
View full abstract
-
Y. Yamashita, S. Yamamoto, K. Mukai, J. Yoshinobu, Y. Harada, T. Tokus ...
Article type: Regular Paper
Subject area: Electronic Properties
2006 Volume 4 Pages
280-284
Published: 2006
Released on J-STAGE: March 24, 2006
JOURNAL
FREE ACCESS
For today's silicon based devices, understanding the SiO
2/Si(111) interface on atomic level is an important subject for fabricating superior devices. However, despite of many studies on the SiO
2/Si(111) interface, the interfacial valence electronic states have been typically evaluated as the average and not as individual states. In the present study, we successfully observed valence electronic states of particular atoms at the SiO
2/Si(111) interface for the first time using soft x-ray absorption and emission spectroscopy. In addition, comparing the experimental results to first-principles calculations revealed local interfacial properties. [DOI: 10.1380/ejssnt.2006.280]
View full abstract
-
Tomohide Takami, Hironobu Kusaka, Isao Kusunoki
Article type: Regular Paper
Subject area: Structures
2006 Volume 4 Pages
285-293
Published: 2006
Released on J-STAGE: March 26, 2006
JOURNAL
FREE ACCESS
The initial stage of the structural change in a clean Si(100)-2 × 1 surface induced by annealing at 640°C and exposure to ethylene gas was studied by reflection high-energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). The RHEED pattern included SiC spots and STM images revealed SiC particles on the surface, which confirmed the carbonization of the Si surface. At a different area of the same sample, the RHEED pattern showed both twice the periodicity of surface spots which indicates a flat surface region and transmitted bulk Si spots which indicates the initial stage of voids. The STM images of the flat region showed a 2 × n (6 ≤ n ≤ 12) reconstruction. The topography of the 2 × n STM image depended on the bias voltage. The 2 × n reconstruction was clearly induced by carbon impurities; STM images were similar to those in previous studies in which structures were formed by various kinds of impurities or contaminations. [DOI: 10.1380/ejssnt.2006.285]
View full abstract
-
Katsunori Tagami, Masaru Tsukada
Article type: Regular Paper
Subject area: Nano-Science and -Technology
2006 Volume 4 Pages
299-306
Published: 2006
Released on J-STAGE: March 31, 2006
JOURNAL
FREE ACCESS
The non-contact atomic force microscopy (nc-AFM) images of the single alkanethiolate molecules embedded in the bicyclo[2,2,2]octylmethylthiolate (BCO) self-assembled monolayer (SAM) are simulated using the all-atom empirical force field model. The tip is modeled by the chemically inactive and unpolarized carbon nanocone apex. When the alkyl chain is longer than the BCO matrix, the protruded chain is observed to be lower than its actual height. Even if the alkyl chain has a similar height to the BCO, the former is observed to be slightly lower than the latter. These findings indicate that even when the chemical and electrostatic interactions are not relevant for imaging, the nc-AFM images do not always give true topographical information of the molecules under the tip. [DOI: 10.1380/ejssnt.2006.299]
View full abstract
-
H. Goto, K. Sudoh, H. Iwasaki
Article type: Regular Paper
Subject area: Reaction and Dynamics
2006 Volume 4 Pages
307-310
Published: 2006
Released on J-STAGE: March 31, 2006
JOURNAL
FREE ACCESS
We have studied the decay kinetics of two-dimensional holes on SrTiO
3(001) surfaces using scanning tunneling microscopy(STM). We have created nanoscale unit-cell-deep holes on (001) terraces using a STM nanofabrication technique, and have performed real-time observation of the decay of the holes in a temperature rage of 700 ∼ 800°C. From the observed time dependence of hole areas during decay, we have found that the rate limiting process of the decay is the surface diffusion. We have also investigated the effect of the existence of substrate steps and islands on the hole decay. [DOI: 10.1380/ejssnt.2006.307]
View full abstract
-
Abbas A. Rostami, Mark T. McDermott
Article type: Regular Paper
Subject area: Nano-Science and -Technology
2006 Volume 4 Pages
419-425
Published: 2006
Released on J-STAGE: April 19, 2006
JOURNAL
FREE ACCESS
The deposition of 4-nitroazobenzene (NAB) on carbon electrodes were achieved by the electrochemical reduction of 4-Nitro-4’-diazonium azobenzene tetrafluoroborate in anhydrous acetonitrile media using cyclic voltammetry technique at room temperature. The modified surfaces were examined as voltammetric electrodes for Fc/Fc
+, Ru(NH
3)
63+/2+, IrCl
62-/3-, Fc(COOH)
2, Fe(phen)
33+/2+ and Ru(bpy)
33+/2+. The modified electrodes exhibited very slow electron transfer in compare to unmodified surfaces, by factors that varied with the redox systems. However, after scanning the modified electrode in 0.1M n-tetrabutylammonium tetrafluoroborate (TBABF
4) in acetonitrile from +0.4 to ∼ -0.9 V versus Ag/Ag
+ for 25 cycles, the modified electrodes exhibited much faster electron transfer kinetics, for some redox systems approaching those observed on unmodified surfaces. The effect is attributed to an apparently irreversible structural change in the NAB monolayer, which increases the rate of electron tunnelling. The transition to the "ON" state is associated with electron injection into the monolayer. Once the monolayer is switched ON, it supports rapid electron exchange with redox systems, but not with dopamine, which requires adsorption to the electrode surfaces. A "switching" electrode may have the potential to impact the field of molecular electronics, which is one of the more popular areas of nanotechnology. [DOI: 10.1380/ejssnt.2006.419]
View full abstract
-
H. Djati Utomo, K. A. Hunter
Article type: Regular Paper
Subject area: Environmental and Energy Technology
2006 Volume 4 Pages
504-506
Published: 2006
Released on J-STAGE: May 19, 2006
JOURNAL
FREE ACCESS
The adsorption of the heavy metal ions Cu
2+, Zn
2+, Cd
2+ and Pb
2+ from aqueous solution by used coffee grounds has been investigated as a potential low-cost treatment method for heavy metal-containing waste waters that is based on a readily available natural by-product. The results show that metal ion adsorption is efficient over a fairly wide pH range and adsorbed metals are reversibly leached from the exhausted coffee by dilute acid without significant loss of the adsorptive capacity for subsequent re-use. [DOI: 10.1380/ejssnt.2006.504]
View full abstract
-
Motoi Hirayama, Jun Nakamura, Akiko Natori
Article type: Regular Paper
Subject area: Electronic Properties
2006 Volume 4 Pages
528-533
Published: 2006
Released on J-STAGE: June 09, 2006
JOURNAL
FREE ACCESS
We have investigated atomic arrangements and electronic properties of two-dimensional Si compounds having the Si(111) skeletons with H and/or OH-radicals terminators, using first-principles calculations within the density functional theory. A mechanism of the onset of a direct gap for the planar siloxene has been clarified from the chemical bonding points of view. The direct energy gap does not change with increasing thickness of the Si-skeleton of the planar siloxene, but the indirect one decreases: the direct and indirect gaps of the planar siloxene are associated with the surface state and the Si-skeleton states, respectively. If both surfaces of the planar siloxene are terminated with the OH-radicals, the stacking of the Si-skeleton changes from the diamond structure to the Wurtzite one as the Si-skeleton thickness increases. In such artificial compounds, a direct gap appears only at the thinnest Si thickness as well as the case of the planar siloxene. [DOI: 10.1380/ejssnt.2006.528]
View full abstract
-
T. Takano, M. Wilde, M. Matsumoto, T. Okano, K. Fukutani
Article type: Regular Paper
Subject area: Structures
2006 Volume 4 Pages
534-538
Published: 2006
Released on J-STAGE: June 10, 2006
JOURNAL
FREE ACCESS
Ultra-thin films of Cr
2O
3(0001) grown on Cr(110) were investigated by low-energy electron diffraction (LEED). Two samples with different oxide thicknesses were prepared. For the 5 nm-thick film, LEED revealed that the structure changes from 1×1 at 300 K to √3×√3 at 150 K and 1×1 at 100 K, which is in good agreement with a previous study. For the film thicker than 10 nm, LEED spot intensities were found to change with the sample temperature. LEED I-V curves shifted towards higher energy at 100 K compared to 300 K, which is attributed to a change of the mean inner potential. The origin of this change of the mean inner potential is discussed. [DOI: 10.1380/ejssnt.2006.534]
View full abstract
-
Katsutoshi Fujiwara, Akira Ishii, Toshikazu Ebisuzaki, Tomoki Abe, Kos ...
Article type: Regular Paper
Subject area: Crystal Growth
2006 Volume 4 Pages
544-547
Published: 2006
Released on J-STAGE: June 16, 2006
JOURNAL
FREE ACCESS
We have investigated the growth mechanisms of ZnO on the c-plane sapphire(0001) substrates by the first-principles calculation. The first-principles total energy calculations of a sapphire slab with an isolated zinc adatom and an isolated oxygen adatom explain the experimental results such that the in-plane alignment between the ZnO and the sapphire is [10-10]ZnO//[11-20] sapphire. Moreover, from the experimental and theoretical results of GaN/sapphire growth mechanisms, the change of the polarity is very important for the migration barrier energy. The relative total energies for the isolated zinc adatom on the sapphire(0001) surface is very small while that for the isolated oxygen adatom on the sapphire(0001) surface is very large. When analogizing these relative energies with the experimental and theoretical results of GaN/sapphire growth mechanisms, we expect that the polarity of grown ZnO film on the sapphire substrate is the O-polarity. And the polarity of the direct growth of ZnO on the sapphire (0001) substrate does not change from the O-polarity under any growth conditions without using the low-temperature amorphous ZnO buffer layer. [DOI: 10.1380/ejssnt.2006.544]
View full abstract
-
Katsunori Tagami, Masaru Tsukada, Rehana Afrin, Hiroshi Sekiguchi, Ats ...
Article type: Regular Paper
Subject area: Bio-Science and -Technology
2006 Volume 4 Pages
552-558
Published: 2006
Released on J-STAGE: June 28, 2006
JOURNAL
FREE ACCESS
The compression process of a single bovine carbonic anhydrase II ( BCA II ) molecule by an atomic force microscope (AFM) tip in ultra high vacuum (UHV) condition is studied by the molecular dynamics (MD) simulations with the all-atom empirical force field model. The temperature is assumed to be 0 and 300 K, and the force curves are calculated with both the tip and surface modeled as rigid planar graphite sheets. At T = 0 K the normal force of the tip increases gently after the tip starts to compress the protein molecule, as the external force by the tip is consumed to relax the turn or coil structures on the outer part of the protein. However, once this region is deformed to take a flat structure, the normal force increases rapidly. The general trend in the force curves at T = 300 K is similar to that observed at T = 0 K, although the relaxation inside the protein is promoted thermally to reduce the normal force observed. Furthermore, the saw-tooth peaks observed in the force curves are found to originate from the sudden collective sliding motion of the residues, which is triggered by the slip of the locally contacting turn or coil structures at the atomic level. [DOI: 10.1380/ejssnt.2006.552]
View full abstract
-
Raid A. Ismail
Article type: Regular Paper
Subject area: Thin Films
2006 Volume 4 Pages
563-565
Published: 2006
Released on J-STAGE: July 04, 2006
JOURNAL
FREE ACCESS
This work presents novel results of structural, optical, and electrical properties of Bi
2O
3 film deposited on glass substrates by rapid thermal oxidation with aid of halogen lamp at 500°C for 45 s in static air condition without post-deposition heat treatment. The structural investigation showed that the grown bismuth trioxide film is polycrystalline and multiphase (α-Bi
2O
3 and β-Bi
2O
3). Optical properties revealed that these films having direct optical band gap of 2.55 eV at 300 K with high transparency in the visible and NIR regions. Furthermore, these results are compared with other published results. [DOI: 10.1380/ejssnt.2006.563]
View full abstract
-
Noritsugu Hashimoto, Tadanori Hashimoto, Hiroyuki Nasu, Yoshitsugu Yam ...
Article type: Regular Paper
Subject area: Nano-Materials
2006 Volume 4 Pages
566-569
Published: 2006
Released on J-STAGE: July 22, 2006
JOURNAL
FREE ACCESS
Ag and TiO
2 particles prepared by the evaporation-condensation method and spray pyrolysis, respectively, were mixed in N
2 gas flow, and then deposited on the SiO
2 glass substrate to form a film. Optical properties of the film thus obtained were evaluated using UV-Visible spectrophotometer and Z-scan technique. As a result, the absorption peak wavelength of Ag particles due to localized surface plasmon resonance (LSPR) was shifted toward longer wavelength side with increasing the concentration of Ti(OC
3H
7)
4 used as a starting material of TiO
2 particles. This indicates that LSPR peak of Ag particles is strongly influenced by TiO
2 particles. Therefore, this method is useful to develop tunable LSPR devices such as optical switches and sensors. Meanwhile, nonlinear refractive index determined by Z-scan technique was negative. [DOI: 10.1380/ejssnt.2006.566]
View full abstract
-
Andriy Okhrimovskyy, Kesami Saito, Kouichi Tsuji
Article type: Regular Paper
Subject area: Thin Films
2006 Volume 4 Pages
579-583
Published: 2006
Released on J-STAGE: August 05, 2006
JOURNAL
FREE ACCESS
The intensity enhancement phenomenon in reflector assisted TXRF has been investigated theoretically. Intensity enhancement effect was presented by focusing of primary and reflected X-ray beam to the sample. Proposed explanation behavior was compared with experimental results. Theoretical calculations are in a good qualitative agreement with experimental data. Based on proposed approach, the incident angle of primary X-rays can be evaluated in the experiment. [DOI: 10.1380/ejssnt.2006.579]
View full abstract
-
T. Suzuki
Article type: Regular Paper
Subject area: Nano-Science and -Technology
2006 Volume 4 Pages
588-592
Published: 2006
Released on J-STAGE: August 22, 2006
JOURNAL
FREE ACCESS
Charge transport through single dibenzo[a,j]coronene (C
32H
16) molecules (DBC) chemisorbed on the Si(001)-2 × 1 surface was investigated by current-voltage (I-V) measurement with scanning tunneling microscopy (STM) at 25°C. The I-V curves taken from two different adsorption structures of the DBC are found to be significantly different. The major DBC species shows periodic steps in the {I-V} curve, as expected from a possible Coulomb blockade, while the minor DBC species shows a similar I-V curve to the Si substrate. This indicates that the adsorption structure of the chemisorbed DBC molecule to the Si surface governs its conductivity behavior. [DOI: 10.1380/ejssnt.2006.588]
View full abstract
-
Satoka Aoyagi, Makoto Dohi, Nobuhiko Kato, Masahiro Kudo, Shinichi Iid ...
Article type: Regular Paper
Subject area: Bio-Science and -Technology
2006 Volume 4 Pages
614-618
Published: 2006
Released on J-STAGE: August 29, 2006
JOURNAL
FREE ACCESS
Orientation of immobilized proteins on bio-devices is important to obtain their high performance. Structural change in a particular area of a protein is also very important for the study of the protein performance and the evaluation of the bio-devices. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is able to analyze upper surface of one layer of molecules. Orientation of immobilized proteins can be evaluated based on determination of a partial structure, representing ensemble of amino acids, on the surface part. The model protein, bovine serum albumin (BSA), is immobilized on the substrate, indium-tin oxide (ITO) glass electrode, by covalent bonding. Two types of the oriented samples were prepared by controlling the binding parts of BSA. The results from TOF-SIMS spectra analysis were compared to the amino acid sequence to examine surface parts of the immobilized BSA at different groups. The surface parts of the BSA molecules immobilized on ITO glass plates with different parts of the molecule, amino groups or carboxyl groups, are evaluated by means of TOF-SIMS. The orientation differences were clearly shown in TOF-SIMS spectra of the samples. Furthermore, fragment-ion-generating parts of immobilized-BSA are determined by fragment ions of particular combinations of amino acids in the sequence of BSA. [DOI: 10.1380/ejssnt.2006.614]
View full abstract
-
Yoshiyuki Kubota, Eben Sy Dy, Hiroshi Nakanishi, Hideaki Kasai, Wilson ...
Article type: Regular Paper
Subject area: Catalysis
2006 Volume 4 Pages
630-635
Published: 2006
Released on J-STAGE: October 17, 2006
JOURNAL
FREE ACCESS
We investigated the interaction of oxomolybdenum porpyhrin (MoO(por)) with O
2 by using first principles calculations. Our calculations indicate that the adsorbed O
2 on MoO(por) does not take an end-on configuration, but a side-on configuration to become more stable. These results can be understood from the differences in the molecular orbital energies and the valence electron densities. The geometric parameters of MoO(por) and MoO(por)(O
2) with a side-on configuration of O
2 are in good agreement with experimental results. [DOI: 10.1380/ejssnt.2006.630]
View full abstract
-
Raid A. Ismail, Ala Al-Naimi, Alaa A. Al-Ani
Article type: Regular Paper
Subject area: Thin Films
2006 Volume 4 Pages
636-639
Published: 2006
Released on J-STAGE: October 20, 2006
JOURNAL
FREE ACCESS
Spray pyrolysis deposition technique has been used to grow ZnO thin films doped with different dopant species (Al, Cu, I). The optical and electrical properties of films were investigated as function of dopant type and concentration. The structural characteristics of undoped and doped ZnO films were studied using X-ray diffraction (XRD). The electrical resistivity as low as 4 × 10
-2 Ωcm was obtained for ZnO:Al with 5 at.% dopant concentration. ZnO:Cu films prepared at specific conditions exhibited p-type conductivity. The optical band gap of doped ZnO films varied from 3.09 eV to 3.2 eV. XRD investigation confirmed that the doped ZnO films had preferred orientation in the direction of (101) plane. [DOI: 10.1380/ejssnt.2006.636]
View full abstract
-
Nelson B. Arboleda Jr., Muneyuki Tsuda, Hideaki Kasai
Article type: Regular Paper
Subject area: Reaction and Dynamics
2006 Volume 4 Pages
640-643
Published: 2006
Released on J-STAGE: October 31, 2006
JOURNAL
FREE ACCESS
We performed a quantum dynamics study on the proton-like hydrogen (H
+) transmission from the platinum (Pt) electrode to the Nafion side chain. In particular, we calculated the transmission probability (T
p) for H
+ from the Pt side to the Nafion side using the coupled-channel method via the local reflection (LORE) matrix scheme and plotted T
p as a function of the H
+ initial translational energy. Our results showed that without quantum effects, H
+ transmission across the Pt-Nafion interface will be impossible to proceed at the operating temperatures (i.e. 353-373 K) of conventional fuel cells. We also found that the asymmetric nature of the barrier in the system we considered enhances the transmission. [DOI: 10.1380/ejssnt.2006.640]
View full abstract
-
Junji Kobayashi, Masanori Owari
Article type: Regular Paper
Subject area: Structures
2006 Volume 4 Pages
644-649
Published: December 12, 2006
Released on J-STAGE: December 12, 2006
JOURNAL
FREE ACCESS
Adsorption behaviors of alkylamine compounds in UPW (ultra pure water) on hydrogen-terminated Si(100) were elucidated mainly by ToF-SIMS. Si wafers cleaned by heat treatment in 500°C were etched in 0.38% HF and soaked in water solution of alkylamine after 1 min UPW rinse. The peak intensity of amine molecular ions and SiH/Si ratio detected by ToF-SIMS are considered to be used as a measure of quantity of adsorbed molecules and surface oxidation, respectively. It was found that hydrophobic amine molecules with longer CH
2 chain tend to be left with high concentration in a very short time of soaking and also tend to have the larger effect on the increase of surface oxidation of hydrogen-terminated surface. The latter phenomenon was explained by an I-effect of alkyl group. [DOI: 10.1380/ejssnt.2006.644]
View full abstract
-
Sergey Andreevich Dotsenko, Nickolay Gennadievich Galkin, Ludmila Vale ...
Article type: Regular Paper
Subject area: Nano-Materials
2006 Volume 4 Pages
650-655
Published: December 12, 2006
Released on J-STAGE: December 12, 2006
JOURNAL
FREE ACCESS
Magic clusters are the smallest ordered quantum dots; hence, they represent promising materials for optoelectronics. However, their optical properties still have not been studied. Therefore, the purpose of this work is investigation of optical properties of magic clusters formed both in reactive (Cr/Si(111)) and non-reactive (In/Si(111)) systems. The 'adsorbate-silicon' system named 'reactive', if reactions resulting in silicide(s) formation take place in it. Using differential reflectance spectroscopy, optical functions of Indium and Chromium magic clusters were obtained. Having analyzed obtained spectra, we conclude that Cr magic clusters are CrSi islands and Si surface covered by In magic clusters is a semiconductor. A new method of obtaining saturation coverage of studied surface structures was proposed. [DOI: 10.1380/ejssnt.2006.650]
View full abstract
-
Olaf Karthaus, Takuto Terayama, Yuichi Hashimoto
Article type: Regular Paper
Subject area: Micro- and Nano-Fabrication
2006 Volume 4 Pages
656-660
Published: December 16, 2006
Released on J-STAGE: December 16, 2006
JOURNAL
FREE ACCESS
Modification of electrode surfaces plays an important role for electronics. Most often, lithography techniques are used, but they suffer from high fabrication cost, material restrictions and size limitations. Here we investigate if dewetting can be used to selectively coat a micron-sized gold stripe electrode on a silicon substrate. [DOI: 10.1380/ejssnt.2006.656]
View full abstract
-
Tadashi Abukawa, Tomoyuki Yamazaki, Shozo Kono
Article type: Regular Paper
Subject area: Structures
2006 Volume 4 Pages
661-668
Published: December 23, 2006
Released on J-STAGE: December 23, 2006
JOURNAL
FREE ACCESS
The usefulness of fully performed constant-momentum-transfer-averaging (CMTA) in low-energy electron diffraction (LEED) has been demonstrated for a single-domain Si(111)4×1-In surface. In the fully performed CMTA, thousands of I(V) curves were measured for the single-domain Si(111)4×1-In surface and CMTA intensity profiles were obtained for more than three hundred reciprocal rods in order to directly reconstruct three dimensional (3D) atomic positions of the surface. In the direct reconstruction, the minimum function method, a standard method in X-ray crystallography of the Patterson function analysis, was used. The 3D Si positions so obtained were in excellent agreement with the known heavily-reconstructed surface Si positions of 4×1. Indium atoms were not ‘ visible’ in the present case due to large thermal vibration amplitude of indium atoms for the room-temperature sample, which is not an inherent shortcoming of the fully performed CMTA method. [DOI: 10.1380/ejssnt.2006.661]
View full abstract
-
Noriaki Oyabu, Óscar Custance, Masayuki Abe, Seizo Morita
Article type: Conference -ISSS-4-
Subject area: Micro- and Nano-Fabrication
2006 Volume 4 Pages
1-8
Published: 2006
Released on J-STAGE: January 12, 2006
JOURNAL
FREE ACCESS
A near contact atomic force microscope operated at low-temperature is used for vertical and lateral atom manipulations of selected single atoms on semiconductor surface. The precisely controlled short-range chemical force interaction during a soft nanoindentation with the tip apex atom close to the surface leads to the removal and lateral manipulation of a selected surface adatom, and deposition of a single atom on a selected vacancy at the surface. Besides, the precisely controlled short-range chemical force interaction during a near contact raster scan leads to the sequential lateral atom manipulation. These manipulation processes are purely mechanical, since neither bias voltage nor voltage pulse is applied between probe and sample. Using these different two methods, surface atomic structures on the selected regions were successfully modified. [DOI: 10.1380/ejssnt.2006.1]
View full abstract
-
Alexander Wei
Article type: Conference -ISSS-4-
Subject area: Nano-Science and -Technology
2006 Volume 4 Pages
9-18
Published: 2006
Released on J-STAGE: January 12, 2006
JOURNAL
FREE ACCESS
Gold nanoparticle arrays and gold nanorods produce tunable plasmon responses in the near-infrared (NIR) range and can be used to explore biochemical processes in living systems. Colloidal gold nanoparticles up to 170 nm have been self-assembled into periodic 2D arrays when encapsulated by a novel surfactant (resorcinarene tetrathiol). The arrays are capable of supporting cell adhesion, and can be excellent substrates for surface-enhanced Raman scattering (SERS) at NIR excitations. Spherical "superparticle" ensembles (gold nanoparticles densely packed around submicron silica cores) have also been constructed by self-assembly, and exhibit strong NIR extinction and scattering. These core-shell assemblies have been implanted into live cells as intracellular nanoprobes for detecting chemical influx. Third, gold nanorods can be engineered to have longitudinal plasmon resonances at NIR frequencies, and possess outstanding characteristics as optical contrast agents. Gold nanorods can produce strong two-photon luminescence (TPL), and have been imaged in vivo at the single-particle level while passing through a mouse blood vessel. [DOI: 10.1380/ejssnt.2006.9]
View full abstract
-
Isao Tamai, Taketomo Sato, Hideki Hasegawa, Tamotsu Hashizume
Article type: Conference -ISSS-4-
Subject area: Micro- and Nano-Fabrication
2006 Volume 4 Pages
19-24
Published: 2006
Released on J-STAGE: January 12, 2006
JOURNAL
FREE ACCESS
Attempts were made to further elaborate our experimental growth method and the theoretical growth simulation method for formation of AlGaAs/GaAs QWRs on the (111)B substrates, paying attention to Al composition dependence of growth. A series of repeated growth experiments were carried out on simple one-sided mesa patterns, and from their analysis of the results led to determination of parameter values needed for computer simulation based on the continuum model. The experimental evolution of the cross-sectional structures was well reproduced by simulation, not only on one-side mesa, but also on mesa stripes actually used for wire growth. Finally, an optimum growth design was derived for growth of an array of GaAs triangular QWRs with 40 nm base width on GaAs (111)B substrate by the simulation, and the actual growth experiment confirmed its realization. [DOI: 10.1380/ejssnt.2006.19]
View full abstract
-
T. Emoto, K. Akimoto, K. Ito, J. Ghatak, P. V. Satyam
Article type: Conference -ISSS-4-
Subject area: Structures
2006 Volume 4 Pages
25-31
Published: 2006
Released on J-STAGE: January 12, 2006
JOURNAL
FREE ACCESS
Lattice strain of Si(111) implanted 1.5 MeV Au
2+ ion was investigated by extremely asymmetric x-ray diffraction. The measured rocking curves were consisted of a bulk peak and a broad sub peak accompanying with intensity oscillation. Analysis of the strain distribution was done by fitting of the measured curve with curves calculated by a dynamical diffraction theory. The resultant strain profile shows introduction of a tensile strain in extent of 500 nm. Comparing the strain profiles with the distributions of the projected range and the vacancy calculated by the TRIM code, it was concluded that the lattice strain is contributed by not only the defect due to collision event but also the interstitials of Au ion. In addition, we found that the global shape of the broad sub peak is very sensitive to the strain distribution within the depth of ∼80 nm. [DOI: 10.1380/ejssnt.2006.25]
View full abstract
-
Kensuke Inai, Kaoru Ohya
Article type: Conference -ISSS-4-
Subject area: Structures
2006 Volume 4 Pages
32-38
Published: 2006
Released on J-STAGE: January 12, 2006
JOURNAL
FREE ACCESS
A computer simulation model is presented for ion induced deposition and sputtering in two-dimensional topographic surfaces. The model combines dynamic Monte Carlo simulation of the collision cascade with surface topography simulation, which treats compositional changes self-consistently with the evolution of the surface. An application is presented: erosion and deposition of a ripple surface of carbon irradiated by tungsten ions. Due to the deposition of implanted particles and the redeposition of sputtered particles, the surface topography drastically changes. Sharp wedges are formed on the ripple surface. With increasing ion fluence and energy, the surface is dominated by an oscillatory feature, where the initial ripple structure disappears. Since the redeposition is more for a steep slope than for a gentle slope, the redeposition produces both a peaked region and a shadowed region on the surface against the next redeposition. The surface topography changes strongly influence the W concentration in a W-C mixed layer formed on the C bulk. [DOI: 10.1380/ejssnt.2006.32]
View full abstract
-
T. Nomoto, S. Yagi, K. Soda, G. Kutluk, H. Sumida, E. Hashimoto, M. Ta ...
Article type: Conference -ISSS-4-
Subject area: Catalysis
2006 Volume 4 Pages
39-45
Published: 2006
Released on J-STAGE: January 12, 2006
JOURNAL
FREE ACCESS
The temperature dependent reaction of dimethyl sulfide (CH
3)
2S : DMS on Rh(100) over the temperature range of 90-300 K and the surface reaction of DMS depending on the morphology of Rh(100) surface have been studied with Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS) and Sulfur K-edge Near Edge X-ray Absorption Fine Structure (NEXAFS) techniques. DMS molecules adsorb molecularly on 850 K annealed Rh(100) surface at 90 K, and some of DMS are dissociated into methanethiolate CH
3S- : MT or atomic sulfur as the temperature of the substrate increases. The temperature dependent reduction of the total coverage of sulfur indicates that some of sulfur-containing molecules desorb from the surface. On the other hand, it is found that DMS decomposes into atomic S on 1000 K annealed Rh(100) surface at 90 K. These results indicate that the dissociative reaction of DMS/Rh(100) is more sensitive to the surface morphology than that of Cu(100). [DOI: 10.1380/ejssnt.2006.39]
View full abstract
-
Sri Juari Santosa, Siti Sundari, Sri Sudiono, W. H. Rahmanto
Article type: Conference -ISSS-4-
Subject area: Nano-Science and -Technology
2006 Volume 4 Pages
46-52
Published: 2006
Released on J-STAGE: January 12, 2006
JOURNAL
FREE ACCESS
Synthesis of a new type of adsorbent has been conducted by immobilizing peat soil humic acid (HA) on chitin isolated from crab shell waste. The adsorbent was then applied to adsorb Cu(II) in aqueous medium. The HA was extracted from peat soil of Gambut District, South Kalimantan, Indonesia; while the chitin was isolated from marine crab shell waste of seafood restaurants. The extraction of HA was performed by the commonly used alkaline extraction in NaOH 0.1 M solution, and the isolation of chitin was conducted through deproteination using NaOH 3.5%(w/v) and followed by removal of inorganic impurities using HCl 1 M. The extracted HA and the isolated chitin were characterized by Fourier Transform Infra Red (FT-IR) spectroscopy. Parameters investigated in this study consisted of method of HA immobilization on chitin, stability test of the immobilized HA, as well as rate, capacity, and energy of adsorption. The FT-IR spectra revealed the presence of main functional groups of COOH and OH (phenolic- and alcoholic-OH) in HA, and those of NH, C=O, CH
3, and OH groups in chitin. The immobilization of HA on chitin was successfully done by reacting gelatinous chitin (40 g) in 250 mL of HCl 0.5 M and solution of HA (4 g) in 500 mL of NaOH 0.5 M. This immobilization produced an adsorbent of humic acid immobilized on chitin (Chitin-HA) with the content of HA was 1.98%(w/w). The HA immobilized was stable in the acidity range of pH 3.0 to 11.0. At the acidity giving maximum adsorption, i.e. pH 4, the first order rate constant, capacity, and energy of adsorption of Cu(II) on the HAC were 4.6 × 10
-4 min-1, 0.282 mmol/g, and 20.35 kJ/mol, respectively. Compared to the adsorption of Cu(II) on chitin, the first order rate constant and capacity of adsorption of Cu(II) on the Chitin-HA were, respectively, 1.24 and 1.42 time higher; while the adsorption energy was 0.90 time smaller. [DOI: 10.1380/ejssnt.2006.46]
View full abstract
-
O. P. Chikalova-Luzina, N. N. Ledentsov
Article type: Conference -ISSS-4-
Subject area: Structures
2006 Volume 4 Pages
53-57
Published: 2006
Released on J-STAGE: January 12, 2006
JOURNAL
FREE ACCESS
A thermodynamic analysis of surface-phase equilibria in the MBE growth of In
1-xGa
xAs layers on lattice-mismatched GaAs and InP substrates is done. It is shown that, in In-stabilized conditions, the substrate-induced strain enhances the arsenic equilibrium pressure over In-Ga-As liquid phase in the whole range of the solid phase composition in the case of GaAs substrate, whereas in the case of the InP substrate, the pressure is enhanced by the strain at x<0.47 and lowered at x>0.47. For both substrates, locking the surface monolayer composition occurs. In the As-stabilized conditions, the strain results in the lattice-pulling effect. [DOI: 10.1380/ejssnt.2006.53]
View full abstract
-
Yoshinori Kato, Kohji Nakamura, Toru Akiyama, Tomonori Ito
Article type: Conference -ISSS-4-
Subject area: Electronic Properties
2006 Volume 4 Pages
58-62
Published: 2006
Released on J-STAGE: January 12, 2006
JOURNAL
FREE ACCESS
Magnetic structures at zinc-blende ferromagnetic (FM) and antiferromagnetic (AFM) interfaces, CrAs/Cr, CrAs/GaAs/Cr, and CrSe/MnSe, were investigated by means of the full-potential linearized augmented plane-wave method in order to search the half-metallic exchange bias interfaces. The CrAs/Cr structure is found to lose the half-metallicity at the CrAs interface while the CrAs/GaAs/Cr structure retains the half-metallicity but the energy difference between parallel and antiparallel moment alignments of the FM and AFM layer at the interface significantly reduces. In contrast, the CrSe/MnSe interface induces an excellent half-metallicity, which importantly offers a key ingredient as a promising half-metallic exchange bias. [DOI: 10.1380/ejssnt.2006.58]
View full abstract
-
Yutaka Wakayama, Tadashi Mitsui, Tsunenobu Onodera, Hidetoshi Oikawa, ...
Article type: Conference -ISSS-4-
Subject area: Crystal Growth
2006 Volume 4 Pages
69-73
Published: 2006
Released on J-STAGE: January 19, 2006
JOURNAL
FREE ACCESS
The main aims of this study were to explore a new technique for growing molecular nanocrystals and to examine their optical properties. To grow nanocrystals, we applied a vacuum evaporation technique. Small perylene nanocrystals (ca. 200 nm) at a high density (7.6 μm
-2) were produced by ultra-rapid evaporation on a pattern-indented Si surface. A perylene-3,4,9,10-tetracarboxylic-3,4,9,10-dianhydride (PTCDA) buffer layer was found to be effective for further downsizing of the nanocrystals and for preserving their fluorescence properties originating from the nanoscale size effect. [DOI: 10.1380/ejssnt.2006.69]
View full abstract
-
Naoki Mimura, Zhaoxia Song, Susumu Tsubota, Hiromi Yamashita, S. Ted O ...
Article type: Conference -ISSS-4-
Subject area: Catalysis
2006 Volume 4 Pages
74-77
Published: 2006
Released on J-STAGE: January 19, 2006
JOURNAL
FREE ACCESS
Effective Ti catalysts were found for the vapor phase synthesis of propylene oxide, one of the most challenging reactions in heterogeneous catalysis. The observation that the reaction was enhanced by the presence of a post-catalytic bed volume indicated that the reaction occurred through a homogeneous chain reaction, likely initiated by surface radical generation. EXAFS analysis of the SiO
2-supported catalysts indicated that active samples had Ti oxide clusters on the support. The catalytic activity was stable for 500-600 min, and indicated a promising catalytic system. [DOI: 10.1380/ejssnt.2006.74]
View full abstract
-
Satofumi Souma, Takahiro Yamamoto, Kazuyuki Watanabe
Article type: Conference -ISSS-4-
Subject area: Electronic Properties
2006 Volume 4 Pages
78-83
Published: 2006
Released on J-STAGE: January 19, 2006
JOURNAL
FREE ACCESS
We present a theoretical study of the electronic transport through finite-sized nano-scale graphitic ribbon under the finite bias voltage. By making use of the self-consistent charge density functional tight-binding method along with the Keldysh nonequilibrium Green's function formalism, we obtain remarkable nonlinear behaviors of the current-voltage characteristics of graphitic ribbons, which are found to be attributed to their unique electronic structures by analyzing the energy distribution of the transmission probabilities. [DOI: 10.1380/ejssnt.2006.78]
View full abstract
-
Subhashis Gangopadhyay, Thomas Schmidt, Jens Falta
Article type: Conference -ISSS-4-
Subject area: Thin Films
2006 Volume 4 Pages
84-89
Published: 2006
Released on J-STAGE: January 19, 2006
JOURNAL
FREE ACCESS
The nucleation of silicon nitride films on Si(111) using a radio frequency nitrogen plasma source has been investigated by scanning tunneling microscopy. The initial nucleation of Si
3N
4 is always observed at the steps, i.e., either at the step-edges of the initial Si(111) surface or at the step edges of vacancy islands (etch pits) formed on the terrace areas. With increasing nitridation temperature the nitrified patches become larger with lower density and show a triangular shape. After post annealing the triangular nucleation patches at the step-edges disappear and free-standing Si
3N
4 islands are observed with a hexagonal shape. Nitridation at high temperatures or post-annealing improves the crystalline quality of the nitride films and an atomically resolved honeycomb-like ”8×8” surface reconstruction is observed in STM for thin Si
3N
4 films grown at 850°C. [DOI: 10.1380/ejssnt.2006.84]
View full abstract
-
Subhashis Gangopadhyay, Thomas Schmidt, Sven Einfeldt, Tomohiro Yamagu ...
Article type: Conference -ISSS-4-
Subject area: Nano-Materials
2006 Volume 4 Pages
90-95
Published: 2006
Released on J-STAGE: January 19, 2006
JOURNAL
FREE ACCESS
Growth and morphology of metal organic vapour phase epitaxy (MOVPE) deposited InGaN nano-islands and molecular beam epitaxy (MBE) grown GaN films on GaN(0001) template layers on sapphire substrates have been investigated using scanning tunneling microscopy. For MOVPE InGaN growth, the nucleation of self-organized nano-structures can be achieved by a careful choice of the growth temperature, the In partial pressure, the growth rate and V/III flux ratio. For growth at 650°C, large spiral disc-like islands are found, preferentially nucleating at GaN substrate defects. At 600°C, islands of smaller average size are observed. Lowering the In flux at this temperature, a homogeneous nucleation of small quantum dot like islands with a density of 10
12/cm
2 is found. For homoepitaxial MBE growth of thin GaN layers on GaN templates, a layer-by-layer growth mode is observed for Ga rich growth conditions. For growth at 750°C, an atomically resolved 4×4 surface reconstruction with a high defect density is found in the initial growth stage. However, subsequent growth at 790°C leads to the formation of one dimensional nanoclusters of about 3 nm lateral spacing. For GaN growth at a lower Ga-flux, a rougher surface morphology and three dimensional growth is observed. Independent on the Ga flux, one-dimensional nanostructures appear after prolonged growth at higher temperature, which are attribute to the impact of ions emerging from the N-plasma. [DOI: 10.1380/ejssnt.2006.90]
View full abstract
-
Masaya Toda, Akiko Nakamura Itakura, Karsten Büscher, Karlheinz G ...
Article type: Conference -ISSS-4-
Subject area: Thin Films
2006 Volume 4 Pages
96-99
Published: 2006
Released on J-STAGE: January 19, 2006
JOURNAL
FREE ACCESS
We studied the mechanical stress during the adsorption process of polyallylamine hydrochloride (PAH) and polystyrenesulfonate (PSS) polyelectrolytes using highly sensitive micromechancial cantilever sensors (MCS). Single side adsorption was achieved by functionalizing individual MCS with a 2-mercatoethylamine (2-MEA) self-assembled monolayers. Exposure of the MCS to PAH solution resulted in a constant surface stress change of 1.6±0.2 N/m between the 2-MEA functionalized and silicon sensors. We attribute the surface stress change to the formation of a stable PAH polyelectrolyte layer on top of the silicon surface. We found that a second layer consisting of PSS did not result in a negligible surface stress change. [DOI: 10.1380/ejssnt.2006.96]
View full abstract
-
S. Kumashiro, H. Tanaka, Y. Kawamata, H. Yanagisawa, K. Momose, G. Nak ...
Article type: Conference -ISSS-4-
Subject area: Electronic Properties
2006 Volume 4 Pages
100-104
Published: 2006
Released on J-STAGE: January 19, 2006
JOURNAL
FREE ACCESS
We have investigated the surface electronic structures of transition-metal diboride (0001) surfaces by angle-resolved ultraviolet photoelectron spectroscopy (ARUPS) and ab-initio calculations based on the slab model with 13 layers. In the spectra of NbB
2 and TaB
2, the peaks near -1 eV blow E
F are derived from the π band of their surface graphitic boron layer. As compared with graphene, the dispersion curves of the π bonds are greatly modulated by the hybridization of B-π orbits with the metal d orbits. On the other hand, the similar peaks were not observed in spectra of ZrB
2, of which the surface is terminated with Zr atoms. [DOI: 10.1380/ejssnt.2006.100]
View full abstract
-
Y. Miyauchi, H. Sano, G. Mizutani
Article type: Conference -ISSS-4-
Subject area: Reaction and Dynamics
2006 Volume 4 Pages
105-109
Published: 2006
Released on J-STAGE: January 20, 2006
JOURNAL
FREE ACCESS
In order to obtain the spatial distribution of hydrogen desorption by ultraviolet (UV) laser pulses from a hydrogen terminated Si (H-Si) surface, optical second harmonic (SH) intensity images of the surface have been observed in ultra high vacuum. The observed SH signal included both contributions of the hydrogen deficiency on the H-Si surface and the surface damage. The spatial distribution of the hydrogen deficiency has been obtained from the difference between the SH intensity images before and after the hydrogen re-termination. The hydrogen desorption occurred above the threshold fluence of ∼40 mJ/cm
2, and the total amount of the hydrogen desorption increased monotonically as a function of the UV laser pulse energy. It is suggested that the observed hydrogen desorption may have resulted from the laser induced thermal desorption (LITD) mechanism. [DOI: 10.1380/ejssnt.2006.105]
View full abstract
-
Makoto Ishikawa, Masamichi Yoshimura, Kazuyuki Ueda
Article type: Conference -ISSS-4-
Subject area: Nano-Science and -Technology
2006 Volume 4 Pages
115-117
Published: 2006
Released on J-STAGE: January 20, 2006
JOURNAL
FREE ACCESS
A null method, using a bridged circuit, is applied to the so-called four-point probe method using highly resistance probes. A commercial resistor (150 kΩ-10 MΩ) is serially connected with a voltage measurement probe (made of tungsten) in order to give high resistance. The resistivity of a patterned Pt-Pd film about 50 nm thick is successfully measured for the probe spacing down to the submicron scale. The obtained values of resistance remain unchanged irrespective of the inserted resistors. [DOI: 10.1380/ejssnt.2006.115]
View full abstract
-
Yoshimi Horio
Article type: Conference -ISSS-4-
Subject area: Structures
2006 Volume 4 Pages
118-123
Published: 2006
Released on J-STAGE: January 26, 2006
JOURNAL
FREE ACCESS
A new reflection high-energy electron diffraction (RHEED) apparatus equipped with a hemispherical fluorescent screen upon a sample surface has been constructed. We call it astrodome screen, namely, the apparatus is named as astrodome RHEED. For the observation of Kikuchi pattern in RHEED experiment, the astrodome screen is effective because of the relatively short escape depth of Kikuchi electrons arising in bulk. Diffraction patterns have been observed in the astrodome screen for Si(111)7 × 7 clean surface, and the glancing angle and the acceleration voltage dependences were investigated. It has been found that some circular patterns exist in the Kikuchi patterns. The circular patterns are considered to be responsible for one-dimensional diffractions from certain atomic rows in bulk. The observed Kikuchi patterns and circular patterns are calculated using simple kinematical theory and a good agreement between the experimental and calculated results has been obtained. [DOI: 10.1380/ejssnt.2006.118]
View full abstract
-
Takehide Miyazaki, Hiromitsu Kato, Hideyo Okushi, Satoshi Yamasaki
Article type: Conference -ISSS-4-
Subject area: Structures
2006 Volume 4 Pages
124-128
Published: 2006
Released on J-STAGE: January 26, 2006
JOURNAL
FREE ACCESS
We present first-principles energetics of a phosphorus (P) impurity atom substitutionally doped in the vicinity of the C(001)-2×1:H and C(111)-1×1:H surfaces. We find that locating the P atom within topmost four C-atomic layers of the C(001)-2×1:H surface substantially lowers the formation energy relative to that for doping in the bulk, where the energy lowering (Δ E
form) is up to ∼4 eV. For C(111)-1×1:H, the Δ E
form is up to ∼2.5 eV. Thus we expect that the doped P atoms may have a strong tendency of segregation close to these surfaces. We will also discuss an implication of our result in the context of a recent experiment of P-doping of the (001) and (111) oriented diamond films [H. Kato, S. Yamasaki and H. Okushi, Appl. Phys. Lett. 86, 222111 (2005)]. [DOI: 10.1380/ejssnt.2006.124]
View full abstract
-
Nobuto Yasui, Hiroshi Inaba, Shinji Sasaki
Article type: Conference -ISSS-4-
Subject area: Thin Films
2006 Volume 4 Pages
129-132
Published: 2006
Released on J-STAGE: January 26, 2006
JOURNAL
FREE ACCESS
Diamond like carbon (DLC) films have attracted increasing attention in a variety of industries due to their excellent mechanical and chemical properties. To meet the demands from the emerging industries, such as micro electro mechanical systems (MEMS), a considerable number of research studies have been conducted to advance the technology for thin DLC films fabrication. However, it has been reported that the properties of DLC films vary with thickness, which necessitate further understanding of the mechanism of initial film growth. To elucidate the mechanism of carbon film growth, the present study employs X-ray photoelectron spectroscopy (XPS) to characterize two types of amorphous carbon films fabricated by cathodic vacuum arc discharge and radio-frequency magnetron sputtering. The results indicated that wide range of energy distribution of carbon ions in the cathodic arc discharge caused a decline in the sp
3 ratio with decreasing thicknesses. [DOI: 10.1380/ejssnt.2006.129]
View full abstract
-
Naruo Sasaki, Arihiro Toyoda, Hirooki Saitoh, Noriaki Itamura, Masaya ...
Article type: Conference -ISSS-4-
Subject area: Nano-Science and -Technology
2006 Volume 4 Pages
133-137
Published: 2006
Released on J-STAGE: January 26, 2006
JOURNAL
FREE ACCESS
Supplementary material
Molecular mechanics simulation of atomic-scale peeling of carbon nanotube (CNT) from the graphite substrate surface is performed. We have first obtained the theoretical 'peeling force curve' of the CNT, where the CNT physically adsorbed on the graphite substrate surface is gradually retracted or peeled. In the simulation the single-walled carbon nanotube (SW-CNT) of the (3, 3) armchair type with a length of 40.3 Å comprised of 198 carbon atoms is used. It is clarified that the peeling force curve shows a characteristic behavior mainly dominated by the van der Waals interaction acting between the CNT and the substrate surface. The typical change of the CNT shape during the peeling process, shows a transition from the 'line contact' to the 'point contact', which reflects the covalent bonding interaction. The peeling force curve gives us information of an elementary process of peeling of the CNT. [DOI: 10.1380/ejssnt.2006.133]
View full abstract