Table of contents

Reliable metal nanowire studies requires experimental stringent conditions, as clean samples and environment. In this sense, we have designed and built a dedicated instrument to study electrical transport properties of atomic-size metal contacts based on the mechanically controlled break junction technique, operating at ultra-high-vacuum conditions. Here we describe the chosen setup, its implementation and performance.

Quantum confinement in a single silicon dimer row of the Si(001) surface is presented with data obtained by scanning tunneling spectroscopy. The structure to confine surface electrons was made by depositing tungsten atoms on a silicon dimer row from the tip. The tungsten atoms not only scattered electrons, but also modified potential features of silicon dimers close to them, resulting in the reduction of the effective width of the quantum well. Confinement in this structure is, therefore, explained by a parabolic potential well.

The local barrier height (LBH) of the Bi2212 (Bi₂Sr₂CaCu₂O_8+δ, T_c = 93 K) superconducting single crystal is investigated by using scanning tunneling microscopy / spectroscopy (STM/STS). It is found that the atomically resolved LBH distribution is strongly related with the well-known supermodulation structure of Bi2212 surface. The magnitude of LBH is closely related to the Bi-Bi atomic distance affected by the supermodulation. The comparison with simultaneously obtained conductance spectra shows that there are few correlations between the spatial modulation of gap amplitude and LBH.

We fabricated Fe (iron metal) cores structure by using a low energy Ar⁺ ion beam. A monolayer of ferritin molecule (Fe₂O₃: iron oxide) was adsorbed on the thermal silicon oxide layer. The bombardment energy was optimized using Ar gas by changing the input power after the protein of the monolayer was eliminated with UV/O₃. Though it was resulted in a poor reduction when the time of ion beam was less than 30 sec, Ar⁺ ion beam enabled completely reduction when the time of ion beam was in 60 sec. We reduced the core particles to conductive Fe nanodots. X-ray photoelectron spectroscopy (XPS) measurements confirmed the reduction of the cores. As a result, the diameter of the ferritin nano-structure was 7 nm, which was not identical to that of the iron core in the ferritin after ion beam. Additionally, the Kelvin Probe Force microscopy (KFM) profile was not almost identical between Fe₂O₃ and Fe cores. It is very difficult for conventional Ar⁺ beam processes to fabricate such fine structure of Fe cores, because the high energy ions enhanced the bombardment damage of the iron core in the conventional reduction processes. The results that the change of lattice constant from 0.25 to 0.2 nm corresponds from ferrihydrite (110) to α-Fe(111), respectively, which suggests the ferrihydrite cores reduced to Fe nanodots after ion beam process. Furthurmore, the diameter of the ferritin core decreased from 7 nm to 5 nm after the ion beam process.

Linear-shaped single carbon nanofibers (CNFs) were batch-grown onto commercially available Si cantilevers for atomic force microscope by the Ar⁺-ion-irradiation method (9 cantilevers/batch). The force-curve measurements revealed that the long CNF probes (~ 1 μm in length) were as flexible as the carbon nanotubes probes, whereas the short CNF probes (~ 400 nm in length) were characterized by the rigid nature similar to the Si probes. Thus, the mechanical properties of CNF probes were controllable by the CNF length. The ion-induced CNF probes were metallic in electrical property, and the higher resolution images in scanning spreading resistance microscopy was attained by the CNF probes than by conventional conductive diamond probes, due to the small tip radius, high aspect ratio and the durability of the CNF probes. Because the small-scale batch-fabricated CNF probes showed good uniformity in the size, mechanical and electrical properties, it was concluded that they are promising as practical conductive SPM probes.

We report the first measurement of spatially resolved in-plane conductance of few-layer (one- or two-layer) graphene grown on a SiC substrate, measured using an integrated nanogap probe. The morphology and number of layers of the thermally grown graphene were confirmed by in-situ observation using low energy electron microscopy (LEEM). The gap current (conductance) images were measured using an integrated nanogap probe with a 30-nm-gap on a conventional SPM system in vacuum. Island shapes with a typical width of 30 nm were clearly observed in the conductance image. Single- and double-layer graphene islands could be clearly distinguished, because the conductance of double-layer graphene is about four times that of single-layer graphene. The layer number of few-layer graphene has been successfully estimated from the electrical transport measurement using the integrated nanogap probe.

Scanning spreading resistance microscopy (SSRM) has been applied to study focused ion beam (FIB) induced damage in silicon in dependence on ion irradiation doses from 10¹² cm^-2 to 2·10¹⁶ cm^-2. Starting from the lowest dose, SSRM detects increasing spreading resistance (SR) with increasing dose. For doses from 2·10¹³ cm^-2 to 4·10¹⁴ cm^-2, a slight decrease of SR is measured whereas for higher doses SR again slightly increases. The results are explained by physical effects like decreased carrier mobility due to increased scattering, amorphisation of silicon and precipitation of implanted Ga ions. The results clearly prove that SSRM is well suited for the fast detection of ion beam induced damage with high lateral resolution.

Mechanical control of nanometer size objects and the dynamic behaviour at this length scale are subjects of growing interest. One promising approach to operate and perform quantitative measurements in this regime is to use dissipation processes in atomic force microscopy. We obtained a controlled manipulation of thiol-functionalised gold nanoparticles on silicon dioxide and a measurements of the energy depinning threshold as a function of nanoparticles characteristics by using the AFM microscope in a particular dynamic regime. Detailed procedure and preliminary results will be described in this contribution.

We describe a method based on the use of higher order bending modes of the cantilever of a dynamic force microscope to characterize vibrations of micro and nanomechanical resonators at arbitrarily large resonance frequencies. Our method consists on using a particular cantilever eigenmode for standard feedback control in amplitude modulation operation while another mode is used for detecting and imaging the resonator vibration. In addition, the resonating sample device is driven at or near its resonance frequency with a signal modulated in amplitude at a frequency that matches the resonance of the cantilever eigenmode used for vibration detection. In consequence, this cantilever mode is excited with an amplitude proportional to the resonator vibration, which is detected with an external lock-in amplifier. We show two different application examples of this method. In the first one, acoustic wave vibrations of a film bulk acoustic resonator around 1.6 GHz are imaged. In the second example, bending modes of carbon nanotube resonators up to 3.1 GHz are characterized. In both cases, the method provides subnanometer-scale sensitivity and the capability of providing otherwise inaccessible information about mechanical resonance frequencies, vibration amplitude values and mode shapes.

Novel mode of AFM operation is proposed providing the small, few nanometers tip to sample gap, appropriate for the ANSOM experiments. A set-up open for the run-time adjustments, working at ambient conditions is considered. Efficiency of a method is demonstrated by applying it to the laser nanolithography on different materials with a regular AFM tip.

A scanning probe microscope (SPM), providing an ultra high vacuum (UHV), gas or liquid environment, is presented. It is intended for nanoscale processing and surface research, such as electron controlled chemical lithography (ECCL). The SPM device is mounted on the preparation chamber of a molecular beam epitaxy (MBE) UHV system. Tips and samples can be transferred under vacuum, to and from a small-volume UHV compatible SPM cell which has electrical feedthroughs and gas/liquid inlets and is closable from the MBE system. The air-side of the SPM cell is deformable with three (x,y,z) external piezoelectric actuators, controlling the tip-sample distance, and the (x,y) scanning. Piezoelectric actuators, capacitive displacement sensors and coarse-approach unit are all in a single scanning-unit in air, which is removed for the vacuum system bakeout procedure. Characterization measurements are presented of imaging capabilities in atomic resolution.

Scanning Thermal Microscopy (SThM) is a scanning probe technique that allows the mapping of the thermal properties and/or temperature of a substrate. Developments in this scanning probe technique are of great importance to further the study of thermal transport at the micron and at the nano scale, for instance to better the understanding of heat transport in nano-electronic devices or energy transfer in biological systems. Here we describe: 1) the scanning technique developed to acquire simultaneous images of the topography, the thermal and electrical properties of the substrate using a commercially available Veeco SThM probe; 2) how the SThM probe was modified by mounting a micron-sized diamond pyramid on its tip in order to improve the probe's lateral resolution and the topography resolution tests on the performance of the modified probe.

The exposure of nanostructures to ultrasound renders the opportunity to explore novel methods to control their assembly. In the presence of surface ultrasonic vibration, large Sb nanoparticles on MoS₂ substrates can be laterally displaced using the tip of a compliant AFM cantilever by just increasing the ultrasonic excitation amplitude. Magnetic nanoparticles of about 10–2 nm in diameter are swept by the tip when scanning in contact mode in the absence of ultrasound, but remain undisturbed in the presence of low amplitude ultrasonic vibration. In Atomic Force Microscopy-assisted manipulation of nanoparticles, ultrasonic vibration affects both tip-particle and particle-surface frictional properties.

I report on the feasibility to implement Ultrasonic Atomic Force Microscopy techniques in liquid environments taking advantage of the mechanical diode effect. When using the mechanical diode mode, the inertia of the cantilever allows us to detect ultrasound without monitoring any particular cantilever resonance. It is shown that mechanical diode signals in liquids exhibit a similar dependence on the ultrasonic excitation amplitude and tip-sample normal force as in air. Moreover, Ultrasonic Force Microscopy on samples of biological interest such as lipid bilayers yields to reasonable contrast. In some cases, apparent mechanical-diode signals are detected out-of-contact, with the cantilever far distant from the sample surface.

In this paper the concept of micro- and nano-particle trapping, by jointly utilizing Dielectrophoresis (DEP) and AC Electroosmosis (ACEO), is investigated in a system of parallel electrode arrays. The ACEO fluid velocity is studied by solving a numerical model based on the Debye-Huckel theory.

Furthermore, trapping is studied in a configurable asymmetric electrode array system. A method to trap and manipulate particles is presented that uses an asymmetric configurable electrode system and joint ACEO and DEP in order to move and trap particles at desired locations for further processing. The method is analyzed using a modified Smoluchowski equation that describes the time evolution of the concentration of particles, while limiting the maximum possible concentration to physically realistic limits.

Electron beam induced deposition (EBID) is a promising technique for fabricating nanometre-sized structures in a position-controlled manner. In this technique, organometallic precursors are decomposed by focused electron beams. Then, the non-volatile part of the decomposed precursor deposits on the substrate. As electron beams can be focused to a subnanometre scale in modern electron microscopes, the resolution of EBID is now reaching down to subnanometres. However, the deposits generally contain a large amount of amorphous carbon. This carbon contamination may be the most serious drawback and is preventing practical uses of EBID in nanodevice technology. In this study, nanostructures, such as nanowires, were fabricated by EBID using methyl cyclopenta dienyl platinum trimethyl (MeCpPtMe₃) and iron pentacarbonyl (Fe(CO)₅) precursors in a scanning electron microscope with a custom-made gas introduction system. After the deposition, nanostructures were heated at 400°C in air for 30 min. to remove contaminated carbon. Then, the nanostructures were observed using a transmission electron microscope (TEM). TEM observation revealed that a post-deposition heat-treatment in air resulted in the removal of carbon. The nanostructures made from MeCpPtMe₃ and Fe(CO)₅ became pure Pt and a mixture of hematite and maghemite iron oxides, respectively.

Zinc oxide nanoparticles were synthesized by DC arc plasma in pure oxygen atmosphere. High DC currents were passed through two approaching zinc rods in different oxygen pressures between 50 to 5000 mbars. Samples were characterized by TEM, SEM, XRD and electron diffraction analysis. The formation of zinc oxide nanoparticles were successfully proved by those analyses, although in some cases we had some unwanted materials. The XRD patterns show crystalline formation of zinc oxide, but in low pressures we have an excess peak belong to pure zinc. The height of this peak was reduced by increase in oxygen pressure and finally vanished completely at high pressure. The TEM and SEM images of samples show that in low pressures the samples mainly tend to have rod like shapes structures, but by increasing the oxygen pressure the structures steady revolve to the hexagonal nanocrystals. Upon the resulted data, the best conditions of arc plasma for desire product were inferred.

The surface of an Al plate was treated with a combination of chemical and electrochemical processes for fabrication of surface nanoscale structures on Al plates. Chemical treatments by using acetone and pure water under supersonic waves were conducted on an Al surface. Additional electrochemical process in H₂SO₄ solution created a finer and oriented nanoscale structure on the Al surface. DFM measurement clarified that the nanoscale highly oriented line-structure was successfully created on Al surface. The line distance was estimated approximately 30–40 nm. Molecular patterning on the highly oriented line-structure by copper phthalocyanine (CuPc) was also conducted. The CuPc molecules were put on the nanoscale structure by casting a toluene droplet containing CuPc. DFM and X-ray photoemission spectroscopy (XPS) measurements demonstrated that a molecular pattern that the groove channels were filled with CuPc molecules was fabricated.

Structural and electronic properties for oxygen-adsorbed graphene sheets have been explored using first-principles total-energy calculations within the local spin density functional theory. It has been found that the structural bistability appears with regard to the oxygen adsorption. This bistability corresponds to the formation of epoxy group or ether group, where the ether group phase is more stable than the epoxy group one. Further, the relative stability for the one-side adsorption model to the both-sides one is explored; oxygen atoms prefer to adsorb on both sides of the graphene sheet, while the one-side adsorption structure becomes metastable.

Nanolithography of Si surface using scanning probe microscopy (SPM) scratching with a diamond-coated tip was systematically investigated at a low force regime below 9 μN. The groove patterns with controlled width and depth could be achieved by adjusting the applied force, scan direction and the number of scan cycles. There was no effect of scan speed on the groove size. The minimum groove width of 10 nm was obtained on Si surfaces. Furthermore, more complex nanostructures such as line and space patterns of 30 nm pith and dot arrays of 2.6×10¹⁰ cm^-2 density were realized. SPM scratching with a diamond-coated tip allows nanoscale patterning of Si surfaces to be performed simply.

Tapping mode SPM local oxidation nanolithography with sub-10 nm resolution is investigated by optimizing the applied bias voltage (V), scanning speed (S) and the oscillation amplitude of the cantilever (A). We fabricated Si oxide wires with an average width of 9.8 nm (V = 17.5 V, S = 250 nm/s, A = 292 nm). In SPM local oxidation with tapping mode operation, it is possible to decrease the size of the water meniscus by enhancing the oscillation amplitude of cantilever. Hence, it seems that the water meniscus with sub-10 nm dimensions could be formed by precisely optimizing the oxidation conditions. Moreover, we quantitatively explain the size (width and height) of Si oxide wires with a model based on the oxidation ratio, which is defined as the oxidation time divided by the period of the cantilever oscillation. The model allows us to understand the mechanism of local oxidation in tapping mode operation with amplitude modulation. The results imply that the sub-10 nm resolution could be achieved using tapping mode SPM local oxidation technique with the optimization of the cantilever dynamics.

A simple technique, based on electromigration induced by field emission current, is developed in order to control a tunnel resistance on nanogap electrodes. In this paper, we study a controllability of the resistance on nanogap electrodes by only adjusting the applied current. First, initial planar nanogaps of Ni with below 50 nm separation were defined on SiO₂/Si substrate. Then, the voltage was applied to the nanogaps while monitoring the current passing through the gaps at room temperature. The applied voltage was slowly ramped up until the current reached a preset value. With increasing the preset value from about 1 nA to 30 μA, the resistance of the nanogaps decreased ranging from the order of 100 TΩ to 10 MΩ. These results suggest that this technique can contribute to simplifying a fabrication process of tunneling devices.

Silicon as the basis of the conventional microelectronics industry is expected to be able to integrate both optical and electronic functionalities, leading to optics on silicon chips. Nevertheless, the long radiative lifetimes have until now obstructed efficient light amplification in this material. A novel nano-crystalline approach has disclosed a new prospect for silicon in the laser application field. The observed superior light emitting properties (compared to regular and porous silicon) of silicon nanocrystals (Si-nc's) embedded into amorphous silica (a-SiO₂) are associated with more stable Si/SiO₂ interfaces in the new structures. However, the mechanism of this phenomenon still remains unclear, in part since the atomic structure of the Si-nanocrystal interface has not been known. In the present work, by means of molecular dynamics atomistic models, small Si-nc's embedded into defect-free a-SiO₂ are constructed using two different classical interatomic potentials. After series of annealing runs, the interface structure and defects were carefully analyzed. The results show a thin suboxide layer, along with mostly undercoordinated defects at the interface region.

Microcontact printing (μCP) using PDMS stamps and alkanethiol chemistry is a straightforward method for the structuring of gold layers. We fabricated PDMS stamps from 4'' Si wafers structured by photolithography, as well as from 1'' masters produced with UV-nanoimprint lithography (UV-NIL) directly on a rigid glass back-plate. Large area μm and sub-μm structuring of gold layers was demonstrated using these PDMS stamps. The masters, the stamps and the resulting gold structures were analyzed using scanning electron microscopy (SEM), atomic force microscopy (AFM) and optical microscopy.

Ultra thin film of constantan was potentiostatically electrodeposited on n-type GaAs (111) from a citrate electrolyte containing both copper and nickel ions. SEM and EDX analyses were used to determine the film quality and composition. In order to fabricate high quality constantan alloy the optimum values of deposition potential and solution temperature were respectively found -1.45 V and 22–26 °C using the SEM analyses. The SEM images also showed that the grain size of the alloy extremely increases for the films with thickness of above 400 nm.

Dimensionally Stable Anodes (DSA^®) are used for industrial production of e.g. chlorine and chlorate. It is known that the superior electrocatalytical properties of DSA^® is due to the large effective area of the porous coating. However, this knowledge is mainly found from in situ electrochemical measurements. Here, we used ex situ methods, AFM, TEM and gas porosimetry, for characterization at the nanoscale. The DSA^® coating was found to consist of mono-crystalline grains with a size of 20–30 nm and with pores of about 10 nm in diameter. Using a simple geometrical model an effective area was calculated. For a typical coating thickness, an increase of about 1000 times in the effective surface area was found, which is consistent with in situ estimations. These results suggest that the dominating source of surface enlargement is due to nano-crystallinity.

A silicon/metal nanocomposite is fabricated by electrochemical deposition of a metal (Ni, Co) into the pores of mesoporous silicon prepared from n⁺-silicon consisting of highly oriented channels which are tunable in a range between 40 nm and 100 nm in their diameter and a concomitant interpore spacing. Fourier transform infrared (FTIR) measurements give details about the top surface as well as the interior surface of the pore walls. IR optical investigations are used to determine the optical parameters like the refractive index, depending on the porosity of the porous silicon (PS) layer. Porosities between 25% and 80% exhibit an estimated refractive index between 3 and 1.7. The channels of the obtained nanostructured semiconductor are galvanically loaded with a metal of a metal-salt solution. The selective precipitation of metal-nanostructures is performed by pulsed deposition technique with varying electrochemical parameters depending on the deposited metal (Ni, Co). Metal loaded PS specimens show significant different transmission compared to bare PS. Additional absorbance peaks appear in the spectra which are due to the deposition process leading to a modification of the Si/SiO_x/metal-interface. Magnetic characterization of the samples has been performed by SQUID-magnetometry.

Nanostructured diamond doped with boron was prepared using a hot-filament assisted chemical vapour deposition system fed with an ethyl alcohol, hydrogen and argon mixture. The reduction of the diamond grains to the nanoscale was produced by secondary nucleation and defects induced by argon and boron atoms via surface reactions during chemical vapour deposition. Raman measurements show that the samples are nanodiamonds embedded in a matrix of graphite and disordered carbon grains, while morphological investigations using field electron scanning microscopy show that the size of the grains ranges from 20 to 100 nm. The lowest threshold fields achieved were in the 1.6 to 2.4 V/μm range.

Boron-doped carbon nanotubes have been prepared by chemical vapour deposition of ethyl alcohol doped with B₂O₃ using a hot-filament system. Multi-wall carbon nanotubes of diameters in the range of 30 – 100 nm have been observed by field emission scanning electron microscopy (FESEM). Raman measurements indicated that the degree of C-C sp² order decreased with boron doping. Lowest threshold fields achieved were 1.0 V/μm and 2.1 V/μm for undoped and boron-doped samples, respectively.

Some conception of international science-education center on nano science in Vladivostok is presented. The conception is based on internal and external prerequisites. Internal one is high intellectual potential of institutes of Russian Academy of Sciences and universities of Vladivostok and external one is need of countries of Far Eastern region of Asia in high level manpower. The conception takes into account a specific distribution of science and education potential between Russian Academy of Sciences and Russian universities and a specific their dislocation in Vladivostok. First specific dictates some similarity of organization structure and function of international science-education center to typical science-education center in Russia. But as for dislocation of the international science-education center in Vladivostok, it should be near dislocation of institutes of Far Eastern Brunch of Russian Academy of Sciences in Vladivostok, which are dislocated very compactly in suburb zone of Vladivostok.

In the last few years, there has been a strong interest in implementing nano-mechanical devices as mass sensors. Regarding this application, an important question to address is to know to what extent the observed frequency shift is exclusively due to the targeted mass loading. For this purpose, we present a device, a polysilicon double cantilever, with an innovative design that allows the direct determination of the measurement uncertainty. Two almost identical nanomechanical resonators are simultaneously operated: one serves as sensor and the other as reference. In this way, rapid and reliable measurements in air are made possible. In first experimental measurements, some masses in the order of 300 fg, locally deposited by focused ion beam, have been measured with an uncertainty of 30 fg. These results are corroborated by the determination of the deposits size based on SEM images.

A novel technique for high-density data storage that combines heat-assisted magnetic recording (HAMR) with scanning tunneling microscopy (STM) has been proposed. We use the metal-doped single-crystal diamond STM probe as the magnetic recording head for both heating and magnetization of the local fragment of the magnetic surface by applying pulsing emission current. Data is read using the same probe in the magnetic force measurement mode. Due to the presence of the magnetic inclusions diamond probe acts as a permanent magnet mounted on the flexible membrane capable to deform when subjected to the magnetic field coming from the substrate's magnetic layer. The proposed technique can potentially provide data densities up to 1 Tbit/in².

In this paper, we discuss torsional resonance mode atomic force microscopy in frequency modulation (FM-TR-AFM) under ambient conditions. Freshly cleaved chlorite (001) exhibiting brucite-like and mica-like surface areas was investigated in constant amplitude operation in order to visualize topography and frictional properties. The measurements in frequency modulation allow the characterization of dissipative effects due to changes in the lateral forces between tip and sample.

The complex chemical structure of the hair surface is far from being completely understood. Current understanding is based on Rivett's model¹ that was proposed to explain the macroscopic hydrophobic nature of the surface of natural hair. In this model covalently-linked fatty acids are chemically grafted to the amorphous protein (keratin) through a thio-ester linkage^2,3. Nevertheless, experience like wetting and electrical properties of human hair surface⁴ shows that the complexity of the hair surface is not fully understand based on this model in literature. Recent studies in our laboratory show for the first time microscopic evidence of the heterogeneous physico-chemical character of the hair surface. By using Chemical Force Microscopy, the presence of hydrophobic and ionic species are detected and localized, before and after a cosmetic treatment (bleaching). Based on force curve analysis the mapping of the local distribution of hydrophilic and hydrophobic groups of hair surface is obtained. A discussion on a more plausible hair model and its implications will be presented based on these new results.

The cell apoptosis phenomenon was studied by traditional optical microscope with much lower resolution and also observed by Atomic Force Microscope (AFM) with nano-resolution recently. They both detect the cell apoptosis through the change of cell topography.

In this study, the cell apoptosis was investigated via Near-Field Scanning Optical Microscope (NSOM). The cell topography, with nano-scaled resolution, and its optical characteristics were observed by NSOM at the same measurement scanning. The macrophage was chosen as the cell investigated. To understand the cell apoptosis process is the goal set for the research. The apoptosis process was related to the variations of the optical characteristics of the cell.

Light transmission through thin conducting films with determined and non-determined nanoscale profile relief has been considered theoretically. In the case of non-determined profiles our calculations are based on Green's tensor techniques taking into account the first order perturbation theory, when the divergence of rough surface from flat is considered as perturbation. And in the case of determined and periodic profiles ones are based on differential formalism. There are two fundamental types of thin film profiles interaction, namely correlated and anti-correlated films. Both non-determined and determined periodic profiles of thin absorptive films demonstrate essential increase of obtained spectral and angular dependencies of the transmittance in the region of surface plasmon polariton excitation, especially for the case of anti-correlated film contrary to correlated one. It can be explained by complex coupling surface waves at different sides of film.

We report on a theoretical study of optical extinction in a metal film of 15–230 nm in thickness patterned periodically with sub-wavelength nano-holes of 140 nm in diameter. The gold plate was on a thick SiO₂ wafer and the nano-holes as well as the top side of the metal plate were filled with water or solvent. Light was sent in toward the plate from the SiO₂ side. The simulations were performed by solving the Maxwell equations using the scattering matrix method. It was seen that the extinction can, depending on the periodicity of the hole array, show one or several peaks in the visible wavelength range. The positions of the peaks were redshifted when the thickness of the gold plate was decreased. It was found that the peak positions for a thick plate can be identified from a simple surface plasmon dispersion relation.

Intense local fields bound to the surface of engineered metallic nanostructures are currently of a great interest for many applications including enhanced imaging, spectroscopy, sensing or lab-on-a-chip devices. Their resonance characteristics can be tuned by the size, shape, incident optical frequency and polarization state. We present here an investigation of the local field of gold dimers manufactured in an array. Finally, employing retarded electrodynamics, we computationally visualize the field distribution and obtain the spectral response of a unique dimer.

A hydrophobic surface incubated in a solution of protein molecules (insulin monomers) was made into a catalytic surface for amyloid fibril formation by repeatedly incubate, rinse and dry the surface. The present contribution describes how this unexpected transformation occurred and its relation to rapid fibrillation of insulin solutions in contact with the surface. A tentative model of the properties of the catalytic surface is given, corroborated by ellipsometric measurements of the thickness of the organic layer on the surface and by atomic force microscopy. The surfaces used were spontaneously oxidized silicon made hydrophobic through treatment in dichlorodimethylsilane.

At this study we present molecular recognition method which is based on force spectroscopy analysis for biological markers on the whole cell level. The presented method allows recognition of specific cell surface proteins and receptor sites by nanometer accuracy level. Here we demonstrate specific recognition of membrane-bond Osteopontin (OPN) sites over a whole Preosteogenic cell membrane. By merging specific force detection map of the proteins and topography image of the cell, we create a new image (recognition image), which demonstrate the exact locations of the proteins relative to the cell membrane. The recognition results indicate on the strong affinity between the modified tip and the target molecules, therefore, it enables the use of an AFM as a remarkable nanoscale tracking tool at the whole cell level.

The ability to interact with live cells in vitro in combination with either sequential image acquisition or continuous force sensing provide the means for tracking the dynamics of intra- or inter-cell processes. The former operational mode is relatively slow and is most suitable for events where the temporal evolution takes place on a time scale of several minutes to hours. For instance, aspects of cytoskeletal dynamics, cell motility or conformational response to external stimuli fall into this category.

In this study we demonstrate cell responses from exposure to cytochalasin, glutaraldehyde and a tetrazolium salt. Significant changes in mechanical properties and structural features are observed on time scales up to 3 hrs. In addition, comparative studies of cytoskeletal components of dried and living cells are undertaken.

A 2-dimensional simulation tool was designed to investigate the threshold voltage behaviour for a silicon nanowire constructed in a top down approach on silicon on insulator (SOI) material. The simulation shows, assuming a positive charge of +1·10¹¹ cm^-2 between the silicon/silicon dioxide interface and negatively charged surface states on top of the nanowire that the threshold voltage increases with decreasing height of the nanowire.

Sensors for volatile organic compounds (VOC) are of increasing interest for various applications ever since. Here we present a novel method to achieve a fast and reversible response by employing a polymer-metal nanocomposite film with 2-dimensional Au nanoparticle arrays. Our sensors are made out of spin-coated polymer substrates on which we deposit gold clusters with a cluster density near the percolation threshold via thermal evaporation. The sensor operates on the principle of swelling of polymers in the presence of VOC. This leads to a change in the interparticle distance and therefore the conductivity of the composites. The method is fast, easy, precisely to control and the sensor fabrication process produces only a minimum amount of waste (like organic solvents). The degree of swelling primarily depends on the type of polymer and the organic solvent, i.e. solubility parameters of the polymer and the vapor. Therefore, the pattern leads to fingerprints of particular polymers towards different vapors. These fingerprints can be employed as a parameter for detecting different VOCs.

Salmonella enteritidis outbreaks continue to occur, and S. enteritidis-related outbreaks from various food sources have increased public awareness of this pathogen. Conventional methods for pathogens detection and identification are labor-intensive and take days to complete. Some immunological rapid assays are developed, but these assays still require prolonged enrichment steps. Recently developed biosensors have shown great potential for the rapid detection of foodborne pathogens. To develop the biosensor, an interdigitated microelectrode (IME) was fabricated by using semiconductor fabrication process. Anti-Salmonella antibodies were immobilized based on avidin-biotin binding on the surface of the IME to form an active sensing layer. To increase the sensitivity of the sensor, three types of sensors that have different electrode gap sizes (2 μm, 5 μm, 10 μm) were fabricated and tested. The impedimetric biosensor could detect 10³ CFU/mL of Salmonella in pork meat extract with an incubation time of 5 minutes. This method may provide a simple, rapid and sensitive method to detect foodborne pathogens.

Interdigitated electrodes made up of two individually addressable interdigitated comb-like electrode structures have frequently been suggested as ultra sensitive electrochemical biosensors. Since the signal enhancement effects due to cycling of the reduced and oxidized species are strongly dependent on the inter electrode distances, since the nature of the enhancement is due to overlying diffusion layers, interdigitated electrodes with an electrode separation of less then one micrometer are desired for maximum signal amplification. Fabrication of submicron structures can only be made by advanced lithography techniques. By use of electron beam lithography we have fabricated arrays of interdigitated electrodes with an electrode separation distance of 200 nm and an electrode finger width of likewise 200 nm. The entire electrode structure is 100 micrometre times 100 micrometre, and the active electrode area is dictated by the opening in the passivation layer, that is defined by UV lithography. Here we report measurements of redox cycling of ferrocyanide by coupled cyclic voltammograms, where the potential at one of the working electrodes are varied and either an oxidising or reducing potential is applied to the complimentary interdigitated electrode. The measurements show fast conversion and high collection efficiency round 87% as expected for nano-interdigitated electrodes.

This work describes a fabrication and test sequence of microvalves installed on micronozzles. The technique used to fabricate the micronozzles was powder blasting. The microvalves are actuators made from PVDF (polivinylidene fluoride), that is a piezoelectric polymer. The micronozzles have convergent-divergent shape with external diameter of 1mm and throat around 230μm. The polymer have low piezoelectric coefficient, for this reason a bimorph structure with dimensions of 2mm width and 4mm of length was build (two piezoelectric sheets were glued together with opposite polarization). Both sheets are recovered with a conductor thin film used as electrodes. Applying a voltage between the electrodes one sheet expands while the other contracts and this generate a vertical movement to the entire actuator. Appling +300V DC between the electrodes the volume flux rate, for a pressure ratio of 0.5, was 0.36 sccm. Applying -200V DC between the electrodes (that means it closed) the volume flux rate was 0.32 sccm, defining a possible range of flow between 0.32 and 0.36 sccm. The third measurement was performed using AC voltage (200V AC with frequency of 1Hz), where the actuator was oscillating. For pressure ratio of 0.5, the flow rate was 0.62 sccm.

More and more diseases find their cause in malfunctioning genes. There is therefore still need for rapid, low-cost and direct methods to accurately perform genetic analysis. Currently the process takes a long time to complete and is very expensive. We are proposing a system that will be able to isolate white blood cells from blood, lyse them in order to extract the chromosomes and then perform chromosome sorting on chip. As the physical properties of the chromosomes, such as size and dielectric properties, are needed for designing the chip, we have measured them using an AFM microscope.

Wavelength tunability of a microcavity solid-state dye laser is modeled by the finite element method (FEM). We investigate the combination of thermoelastic expansion and thermo-optic effects to tune the microcavity resonant wavelength. An optimized size of the laser microcavity is defined depending on the operation wavelength bandwidth and the glass temperature of the gain material. We also report a new effect of mode depletion specific to our microcavity and excitation scheme.

We present empirical tight-binding calculations of the electronic structure of an array of mechanically connected silicon nanopillars. Structural parameters are chosen so that electrons are confined within each pillar, obtaining an array of effectively decoupled one-dimensional states. We address fabrication issues and present results demonstrating the suitability of the process.

We have investigated the spectral dependence of the optical second harmonic (SH) signal from Cu nanowires deposited on the NaCl (110) faceted templates as a function of the SH photon energies from 2.4 to 4.6 eV. The SH response exhibited a peaked resonance near the SH photon energy of 2hΩ = 4.4 eV for the p-in/p-out and s-in/p-out polarization combinations. At this photon energy the SH response due to the resonant coupling between the fundamental field and the local plasmons in the wires is suggested to be dominant.

A controlled method of manipulation of nanowires was found using the tip of an Atomic Force Microscope (AFM). Manipulation is done in the 'Retrace Lift' mode, where feedback is turned off for the reverse scan and the tip follows a nominal path. The effective manipulation force during the reverse scan can be changed by varying an offset in the height of the tip over the surface. Using this method, we have studied InAs nanowires on different substrates. We have also investigated interactions between wires and with gold features patterned onto the substrates.

MnP and Mn₂P nanowhiskers have been grown by molecular-beam epitaxy (MBE) technique on InP(100) and GaAs(111)B substrates. The catalyst-free growth of nanowhiskers is found to be depended on the formation of Mn-based nanoclusters. The magnetic properties of the samples have been investigated by the measurements in a vibrating sample magnetometer.

We report ab initio investigations of hexagon-shaped [111]/[0001] oriented III-V semiconductor nanowires with varying crystal structure, varying surface passivation, and varying diameter. Their stability is dominated by the free surface energies of the corresponding facets which differ only weakly from those of free surfaces. We observe a phase transition between local zinc-blende and wurtzite geometry of the rods versus the preparation conditions of the surfaces, which is accompanied by a change in the facet orientation.

A modelling framework for short channel nanowire (NW) MOSFETs that covers a wide range of operating conditions is presented. The device electrostatics in the subthreshold regime is dominated by the inter-electrode capacitive coupling, which, in the case of double gate (DG) devices, is analyzed in terms of conformal mapping techniques. Previously, we have shown that these results can also be successfully applied to the NW MOSFET, by performing an appropriate mapping to compensate for the difference in gate control between the two devices. Near and above threshold, the influence of the electronic charge is taken into account in a precise, self-consistent manner by combining suitable model expressions with Poisson's equation. The models are verified by comparison with numerical device simulations.

Nanowire fabrication was implemented on the nanoscale highly-oriented line-structure of Al surface. An Al plate was chemically and successively electrochemically processed by applying dc voltage in H₂SO₄ solution in order to fabricate a nanoscale highly-oriented line structure on the surface. The line width was estimated under 50 nm. As a nanowire polymerization process, aniline monomer solved in pure water and oxidizing agent APS solved in HCl successively dropped on the nanostructured Al surface. The Dynamic force microscopy (DFM) measurements and cross section analysis clarified that the line-structure still remained and the depth of the row became shallow after the polymerization process was applied. Since N 1s core-level lines appeared after the aniline polymerization by X-ray photoemission spectroscopy (XPS) measurements, the aniline monomers were polymerized along the line and filled in the row channel.

Electronic structures and optical properties of GaN and ZnO nanowires with diameters of ~1 nm are investigated using the highly precise all-electron full-potential linearized augmented plane-wave (FLAPW) method. The calculated results demonstrate that the band gap energy of both passivated and unpassivated nanowires becomes large compared with the calculated bulk energy gap due to quantum confinement effects. Furthermore, the calculated imaginary part of their dielectric functions exhibit strong anisotropy and there are several side peaks near the absorption edge caused by valence electronic states around the highest-occupied band involved in the large dipole matrix elements. These results demonstrate that we have a firm theoretical framework to predict microscopic properties of semiconductor nanowires.

We propose a facile method for the self-directed growth of ID molecular lines on the H-terminated Si(001) surface. This method employing a single H-free dimer instead of a single DB greatly enhances the stability of the radical intermediate, thereby facilitating the chain reaction for ID molecular lines. The proposed method will stimulate experiments for fabrication of ID molecular lines which are strongly attached to the Si(001) substrate.

We have observed a 17,19-hexatriacontadiyne (HTDY) monolayer on MoS₂(0001) and sashlike polydiacetylene atomic sash (AS) molecules derived from the monolayer by scanning tunnelling microscopy under ultrahigh vacuum. HTDY molecules adsorbed at 150 K start to move around on the surface above 240 K to form relatively unstable columnar structures. The column is converted into the AS by UV irradiation. In most AS molecules on MoS₂(0001), the alkyl chains are in all-trans conformation but their carbon planes are tilted to the polydiacetylene backbone. This conformer, which is one of the most stable structures for an isolated AS molecule, appears on MoS₂(0001) because of very weak molecule-substrate interactions.

We have developed the mechanically controllable break junction system (in-situ MCBJ) to investigate the conductance of a single molecular junction in ultra high vacuum (UHV). Gas or liquid sample of bridging molecules was introduced to metal electrodes with a gas doser. For the introduction of solid sample, a Knudsen cell was used. In the present system, molecular junctions can be prepared without breaking vacuum. Thus, the atomic structure and chemical property of single molecular junction could be well defined. The electrical conductance of a single ethanedithiol molecule bridging between two Au electrodes was investigated with this in-situ MCBJ system. The conductance was determined to be 0.2 G₀ (G₀ = 2_e²/h).

We report in this work a numerical study of the electronic density of states in π-stacked arrays of DNA double-strand segments made up from the nucleotides guanine G, adenine A, cytosine C and thymine T. In order to reveal the relevance of the underlying correlations in the nucleotides distribution, we compare the results for a genomic DNA sequence, considering a segment of the first sequenced human chromosome 22 (Ch 22), with those of two artificial sequences forming a Rudin-Shapiro (RS) as well as a Fibonacci (FB) polyGC quasiperiodic sequences. Our theoretical method uses an electronic tight-binding Hamiltonian suitable to describe the DNA segments modeled by the quasiperiodic chains.

We report a theoretical study of single molecule conduction in open and closed conformations of photochromic dithienylethene molecules attached to metallic leads. Photochromic molecules are attractive candidates for use in molecular electronics because of the switching between different states with different conducting behavior. We also investigate the switching behavior of the molecule based on total energy calculations for intermediate conformations along the reaction path. The results are compared to earlier work.

We study the effects of longitudinal acoustic and optical phonon scatterings on the transport properties of carbon-nanotube devices with micron-order channel length, within the Kubo formula. We investigate the effects of the phonon scatterings with various wave numbers on the conductance. Furthermore, we evaluate the device properties of carbon nanotubes using the cut-off frequencies when the acoustic phonon is excited in the devices. The results presented here indicate the implication to high performance nanotube transistors.

The forces induced by a steady electric current on several atoms, viz., B, C, N, O and F, adsorbed on metallic (5,5) and semiconducting (8,0) carbon nanotubes are calculated using the Non-Equilibrium Green's Function technique combined with density functional theory. We estimate how the current-induced forces will move the atoms along the tubes and we explain these results in terms of charge transfer, modification of the electron density, and chemical bonding properties of the scattering states.

Recently the ballistic transport through organic molecules could be analyzed with submolecular resolution by an extension of ballistic electron emission microscopy. In this work we compare the results of ballistic transport of electrons and holes through C₆₀ molecules deposited onto a Bismuth/Silicon Schottky diode. The study of hole transmission also exhibits molecular a resolved pattern in the transmission images showing the molecular periodicity of the C₆₀ layer.

Using nonequilibrium Green's function technique, we have investigated the ac conductance of poly(C)-poly(G) DNA molecule at low temperature. Our results indicate that thermal fluctuations of DNA hopping energy will play a profound role for the ac conductance. It smoothes out the conductance curves at high ac signal frequency while does not suppress it substantially. The dependences of the ac conductance on the density of states in the contacts, ac signal frequency and temperature are also investigated.

Mechanisms of adsorption and organization of organic molecules on metallic surfaces play a significant role in the growth of chemically and electronically tuned monolayer thin films. Intercommunication between functional groups for individual adsorbates can serve as the primary driving force for monolayer crystallinity as well as electronic structure, especially in the limit of weak interaction between the adsorbate and substrate. In this article we discuss the submonolayer ordering of a chiral molecule, tartaric acid (C₄H₆O₆), weakly bound to an achiral metal surface, Ag(111), as studied with low temperature scanning tunneling microscopy (STM) and differential conductance imaging. Molecularly resolved images of enantiomerically pure (R,R)- and (S,S)-tartaric acid domains on Ag(111) are presented and the role of intermolecular hydrogen bonding in stereospecific domain and superlattice formation is addressed. Additionally, we consider films formed from the deposition of a racemic mixture of tartaric acid enantiomers. Lastly we present differential conductance mapping of tartaric acid molecular domains that highlights an intrinsic decoupling of molecular film electronic states with respect to the metallic lattice. While the chiral expression that drives the formation of enantiomeric domains does not induce stereospecific conductance, we demonstrate electronic differentiation of submonolayer organic domains from the Ag(111) surface.

The interaction of CO with solid surfaces is a topic of fundamental and applied interest. Nowadays there is an increasing attention on alternative energy carriers, like efficient in situ conversion of methanol to hydrogen. There are several studies in the literature about the catalytic activity of Pd and Rh for dehydrogenation of liquid methanol. It was also shown, that the Cu-ZnO, Pd-ZnO catalysts show a high activity for the dehydrogenation of methanol. At the same time these systems can also be used to catalyze the hydrogenation of CO and CO₂ to form methanol. In this work we performed theoretical calculations of 0.75 ML CO coverages on the Pd(111) and Pd(111)-Zn systems. The adsorption of CO on noble metals was already studied using STM techniques. Using the DFT techniques we can calculate the STM images so, we can delineate the detailed structure of the surface alloy films.

Organic molecules often show very complex thermal desorption spectra. If there is an ordered structure the activation energy for desorption E_des will decrease for the first few layers because of the decreasing van der Waals interaction of the layers to the substrate. This is especially true for the system 3,4,9,10 perylene-tetracarboxylic-dianhydride on Cu(111). The spectra consist of three different signals which can be attributed to the second layer, the multilayer and a crystal phase. The numerical algorithm sketched in this paper gives a desorption energy of 2.35eV for the second layer and 2.2eV for the multilayer.

We present here the results of synchrotron radiation-excited UV-photoemission investigation and DFT calculations on vinylferrocene (VFC), a redox molecule suitable for applications in molecular electronics. A detailed assignment is discussed of the valence photoelectron spectra (UPS), which provides new data on the electronic structure and offers a partial re-interpretation of previous assignments on VFC based on theoretical and experimental evidences. Furthermore, the present results can allow for a meaningful comparison of photoemission results from the corresponding hybrid obtained by covalently attaching VFC to Si oriented surfaces.

We report on the electronic properties of Mn₁₂ molecules chemically grafted on the functionalized Au(111) surface studied by means of scanning tunneling microscopy/spectroscopy at room temperature. Reproducible current-voltage curves were obtained from Mn₁₂ molecules showing a large region of low conductance around the Fermi energy. In agreement with the tunneling spectroscopy results the bias voltage variation upon scanning leads to apparent height changes of the Mn₁₂ clusters. We discuss these findings in the light of the recent band structure calculations and electronic transport measurements on single Mn₁₂ molecules.

Chemical-bonding states of metal-molecular interface have been investigated for L-cysteine and thiophene on gold by x-ray photoelectron spectroscopy (XPS) and near edge x-ray adsorption fine structure (NEXAFS). A remarkable difference in Au-S bonding states was found between L-cysteine and thiophene. For mono-layered L-cysteine on gold, the binding energy of S 1s in XPS and the resonance energy at the S K-edge in NEXAFS are higher by 8–9 eV than those for multi-layered film (molecular L-cysteine). In contrast, the S K-edge resonance energy for mono-layered thiophene on gold was 2475.0 eV, which is the same as that for molecular L-cysteine. In S 1s XPS for mono-layered thiophene, two peaks were observed. The higher binging-energy and more intense peak at 2473.4 eV are identified as gold sulfide. The binding energy of smaller peak, whose intensity is less than 1/3 of the higher binding energy peak, is 2472.2 eV, which is the same as that for molecular thiophene. These observations indicate that Au-S interface behavior shows characteristic chemical bond only for the Au-S interface of L-cysteine monolayer on gold substrate.

Here we present a combined photoemission (UPS), metastable deexcitation (MDS) and optical absorption (NEXAFS) at C K-edge study of molecular states of polyacenes grown on Ag(111) and Au(111), from submonolayer to multilayer thicknesses. We focus on the evolution of the HOMO and LUMO molecular states induced by the adsorption from submonolayer to monolayer thickness and we find a different redistribution of these states in the various systems formed at RT: while a strong redistribution of the molecular states takes place in Pn/Ag(111) and Tc/Ag(111) interface, a weaker interaction is indicated for Tc/Au(111).

Three-Terminal ballistic junctions (TBJs) and planar quantum-wire transistors (QWTs) are emerging nanoelectronic devices with various novel electrical properties. In this work, we realize novel nanoelectronic analogue and digital circuits with TBJs and planar QWTs made on In_0.75Ga_0.25As/InP two-dimensional electron gas (2DEG) material. First we show that a single TBJ can work as a frequency mixer or a phase detector. Second, we fabricate an integrated nanostructure containing two planar QWTs, which can be used as an RS flip-flop element. Third, we make a nanoelectronic circuit by the integration of two TBJs and two planar QWTs. This circuit shows the RS flip-flop functionalities with much larger noise margins in both high and low level inputs. All measurements in this work are done at room temperature.

We have fabricated ferromagnetic resonant tunnelling diodes (FRTD's) based on the AlAs/GaAs/AlAs quantum wells and the p-type Mn-doped GaAs emitter layers. At low temperatures a large magnetic field dependence of the tunnelling current appears in the magnetic RTD's in rather low fields (B < 1T), which is not found in nonmagnetic RTD's. The observed decrease of current in the case of the metallic ferromagnetic emitters is explained by a tunnelling anisotropic magnetoresistance effect.

The Mn-doped GaAs thin films were grown on p-type GaAs substrates by using Molecular Beam Epitaxy technique. The Schottky contacts on top of the (Ga,Mn)As layer were made of Pt metal. In contrast to the non-magnetic GaAs Schottky diodes, a large negative magnetoresistance (MR) in the dc current was observed in the magnetic diodes at low temperatures. The contributions to the observed MR effects from the spin dependent tunnelling through the thin Schottky barrier and the negative MR of the semiconducting layer are discussed in detail.

We calculate the electric-field-induced spin splittings in wide slightly asymmetric modulation-doped quantum wells. When spin subbands are anticrossing we demonstrate two-step spin flips as the in-plane wave vector along the [11] direction is increased by 0.002 nm^-1. At the beginning of this interval the y-component flips, at the end the x-component. Simultaneously the energy separation stays roughly constant below 1 μeV and the wave functions are interchanged. A bias change of about 1 meV is sufficient to move the Fermi level from below to above the anticrossing region.

The assembly of two-dimensional molecular structures of zinc porphyrin molecules arising from the dewetting of a porphyrin solution on a mica substrate is investigated using the atomic force microscope (AFM). Both a near equilibrium nucleation and growth process, and a far from equilibrium spinodal dewetting process are observed. By choosing a zinc porphyrin molecule with a prefabricated structure, we are able to control the morphology of the single layer molecular films formed on the substrate.

Self-assembled arrays of atomic chains on Si(111) represent a fascinating family of nanostructures with quasi-one-dimensional electronic properties. These surface reconstructions are stabilized by a variety of adsorbates ranging from alkali and alkaline earth metals to noble and rare earth metals. Combining the complementary strength of dynamical low-energy electron diffraction, scanning tunneling microscopy and angle-resolved photoemission spectroscopy, we recently showed that besides monovalent and divalent adsorbates, trivalent adsorbates are also able to stabilize silicon honeycomb chains. Consequently silicon honeycomb chains emerge as a most stable, universal building block shared by many atomic chain structures. We here present the systematics behind the self-assembly mechanism of these chain systems and relate the valence state of the adsorbate to the accessible symmetries of the chains.

The adsorption on TiO₂ surface of two dipeptides AE (L-alanine-L-glutamic acid) and AK (L-alanine-L-lysine), that are 'building blocks' of the more complex self-complementary amphiphilic oligopeptides and are therefore a good model in the interpretation of the complex peptide spectra, has been investigated both theoretically and experimentally. The chemical structure and composition of thin films of both dipeptides on TiO₂ were investigated by XPS (X-ray photoelectron spectroscopy). Theoretical ab-initio calculations (ΔSCF) were also performed to simulate the spectra allowing a direct comparison between experiment and theory.

We have investigated self-assembled island formation, molecular detail and interesting contrast reversal effects for Er₃N@C₈₀ and Sc₃N@C₈₀ on Au(111) and Ag/Si(111) surfaces using variable temperature scanning tunnelling microscopy (STM) and spectroscopy (STS). The trinitride containing fullerenes have been evaporated onto Ag-passivated Si(111) at room temperature and self-assembled into close-packed 2-D islands. Gentle annealing at 200 – 300°C is required for the formation of close-packed islands with 20 – 50 nm diameter on the Au(111) surface. Variable-voltage STM reveals bias-dependent contrast anomalies within the islands, and at low temperatures (< 90K), intra-molecular resolution of the fullerenes has been achieved. STS measurements indicate that the bright/dark anomalies may be caused by different electron densities of states for the 'normal' and 'anomalous' fullerenes.

The process of electronic-excitation-induced phase separation in GaSb nanoparticles has been studied by transmission electron microscopy from the viewpoint of the relationship between the atomic diffusion and the behaviour of the defects introduced by electronic excitation. When approximately 20 nm-sized GaSb particles kept at 430 K are excited by 25keV electrons, gallium atoms on the lattice points are displaced to form vacancies and gallium interstitials in the crystal. Two-phase separation takes place via the void formation and an increase in lattice constant of GaSb. It is suggested that the vacancy supersaturation near the particle core brings about the void formation and the diffusion of gallium interstitials to the particle surface causes the phase separation.

We give a quantitative estimate of the screened on-site Coulomb repulsion U in carbon nanotubes and graphite. This is obtained by measuring the Auger spectrum of these materials and performing a theoretical study based on the Green's function method proposed by Cini[Solid. St. Comm. 24, 681 (1977)]. The experimental lineshape is very well reproduced by the theory, where only one fit parameter is employed. This allows to extract the value of the screened on-site repulsion between 2p states, which results U = 4.6 eV for nanotubes and U = 2.1 eV for graphite.

Structure of monosaccharide gels formed from glucose-based gelators with organic solvents were studied using SAXS method, in wet state and after drying as xerogels and aerogels. Fractal analysis of the scattering data was carried out. It occurred that these gels essentially change their structure during drying. The structure of the xerogels indicates a strong collapse. The aerogels produced from the apolar gel are also collapsed but, for the slightly stronger polar one, the mechanism of structural change probably includes Ostwald ripening. These results call in question the reasonableness of application of microscopic methods, requiring dry samples, like SEM and TEM, to structural investigations of gels of this type.

Graphite nanofibers (GNF) and multi-wall carbon nanotubes (MWCNT) are mass analyzed utilizing the unique capability of the scanning atom probe. Various clusters of carbon and hydrogen are detected from MWCNT. These are mostly H⁺, H₂⁺, C⁺, CH₃⁺ and C₂H₅⁺. Few cluster ions are detected for the mass rang of 100 – 300. The largest mass peak is C₂₈H₄⁺ with two satellite mass peaks. The abundance of the satellites well agrees with the expected abundance of ¹²C₂₇¹³CH₄ and ¹²C₂₆¹³C₂H₄, 28% and 4%, respectively. No H⁺ mass peak was found for GNF but the significant number of the ions such as C₂H₅⁺, C₃H₇⁺ and C₄H₉⁺ are detected. These ions are detected at the beginning of the mass analysis. After the removal of the surface layer, the detection rate of the largest cluster, C₂₃H₂, increases. The proposed structure of the C₂₈H₄ cluster is a rectangle formed three rows by three rows of hexagonal cells and that of C₂₃H₂ is the triangularly arranged six hexagonal cells. Four carbon atoms of C₂₈H₄ and two carbon atoms of C₂₃H₂ clusters are terminated by hydrogen.

We investigated the surface potential around nanotube channel during CNT-FET operation by scanning Kelvin probe microscopy (SKPM). The results demonstrate that the local surface potential distribution depends on the fabrication process of FET devices. We also measured the transfer characteristic of CNT-FET and compared with the surface potential image. In addition, we investigate the specific FET device with the closed CNT loops into which channel CNT penetrates. The surface potential distribution is completely different with that of a simple single CNT channel. We find that the closed loop of CNT has a capability of trapping the charge inside the loop.

We have synthesized the n-butyl-passivated Si nanoparticles with mean diameter of 1.4 nm by the solution routes, and have carried out the various spectroscopic studies in order to investigate their optical properties, electronic structures, and surface chemistry. It is found that photoluminescence (PL) spectra of these Si nanoparticles strongly depend on the surface conditions. Moreover, it is found their electronic features obtained from the synchrotron-radiation valence-band photoemission and PL spectra are reproduced by the recent quantum Monte Carlo calculation. From the synchrotron-radiation Si 2p core-level photoemission spectra, it is found that their interfacial electronic structure of the present Si nanoparticles is significantly different with that of alkyl-terminated bulk Si surface. From these results, we discuss the detailed electronic and surface chemical properties of alkyl-passivated Si nanoparticles.

DFT calculation of various atomic species on graphene sheet is investigated as prototypes for formation of nano-structures on carbon nanotube (CNT) wall. We investigate computationally adsorption energies and adsorption sites on graphene sheet for a lot of atomic species including transition metals, noble metals, nitrogen and oxygen, using the DFT calculation as a prototype for CNT. The suitable atomic species can be chosen as each application from those results. The calculated results show us that Mo and Ru are bounded strongly on graphene sheet with large diffusion barrier energy. On the other hand, some atomic species has large binding energies with small diffusion barrier energies

The self-assembled fabrication of nanostructure, a dreaming approach in the area of fabrication engineering, is the ultimate goal of this research. A finding was proved through previous research that the size of the self-assembled gold nanoparticles could be controlled with the mole ratio between AuCl₄^- and thiol. In this study, the moles of Au were fixed, only the moles of thiol were adjusted. Five different mole ratios of Au/S with their effect on size uniformity were investigated. The mole ratios were 1:1/16, 1:1/8, 1:1, 1:8, 1:16, respectively. The size distributions of the gold nanoparticles were analyzed by Mac-View analysis software. HR-TEM was used to derive images of self-assembled gold nanoparticles. The result reached was also the higher the mole ratio between AuCl₄^- and thiol the bigger the self-assembled gold nanoparticles. Under the condition of moles of Au fixed, the most homogeneous nanoparticles in size distribution derived with the mole ratio of 1:1/8 between AuCl₄^- and thiol. The obtained nanoparticles could be used, for example, in uniform surface nanofabrication, leading to the fabrication of ordered array of quantum dots.

Organometallics supply carbon and metal catalyst needed for carbon nanotube synthesis. It is shown that experiments involving prior milling of iron-phthalocyanine (FePc, FeC₃₂H₁₆N₈) before pyrolysis at 800 °C in argon produces carbon nanotubes with diameters ranging from 5 to 15 nm. Under the same conditions, the diameters of nanotubes produced from non-milled FePc range from 20 to more than 50 nm. Milling decreases the onset of sublimation of FePc from about 450 to 200 °C and also reduces the activation energy barrier of sublimation at 360 °C from 287 to 193 kJ/mol. This appears to be due to changes in molecular packing of the phthalocyanine precursor. It is suggested that the decrease in nanotube diameter is due to greater homogeneity in the gas phase on pyrolysis after milling, which leads to more systematic capture of carbon species during the catalytic growth of the carbon nanotubes.

We explore field emission properties of a new class of the emitters formed by coating the CNT-polymer composite film onto the flat metal substrate. At present we succeeded to obtain 125 mA for the field emitter diameter of 1 cm at the half-period sine voltage of 50 Hz.

We present here low-temperature Raman and photoluminescence spectra of the C₆₀-cubane rotor-stator compound. We show the continuous evolution of Raman spectra between 77 K and room temperature, with no sharp transition visible at 140 K, the orientational ordering temperature. Low-temperature luminescence spectra of C₆₀ in C₆₀-cubane compound are found to be shifted and better resolved then spectra for pristine C₆₀ at the corresponding temperatures, showing relatively weaker intermolecular interactions. In fact, the solid-state luminescence of C₆₀-cubane is similar to free-molecule C₆₀ luminescence spectra.

Carbon nanotubes (CNTs) - rolled up sheets of graphite - appear in various forms. One way to produce CNTs is chemical vapour deposition (CVD) using carbon containing gases in the presence of catalysts like Fe. For the so-called substrate supported catalyst (SSC) method the catalyst is provided in form of particles at the substrate surface and is thus directly accessible for the carbon containing CVD gas flux to induce CNT growth. In this work we studied five different approaches to create and use catalytic nano-particles for CNT growth. The results of the CVD deposition experiments were analyzed with SEM and TEM. For all five approaches a set of CVD-parameters could be found that led to the formation of dense films of CNTs with different degrees of alignment. HR-TEM analysis showed either fishbone arrangement or multi-walled CNTs depending on the catalyst type.

The electronic, chemical and structural properties of Carbon NanoTubes (CNTs) synthesized by Silicon Carbide surface decomposition were analyzed by Scanning Electron Microscopy (SEM), Scanning Tunnelling Microscopy/Spectroscopy (STM/STS), Electron Energy Loss (EEL) and Raman spectroscopy. A clear relationship between the bonding features and the growth condition (temperature and growth time) is obtained. The morphology of the sample investigated by SEM reveals a well-packed and aligned structure of the CNTs. Different lengths of the CNTs are observed depending on the local temperature of the sample surface. The longest observed CNTs were 500/600 nm. The STS measurements show I-V diode-like characteristic curve which can be used, for instance, as an electron collector in solar cells applications. As a perspective metallic electrode, gold, will be deposited on top of the CNTs in the future, to collect the electron current and investigated by the same techniques.

Composition, electron density and morphology of metal thin-film nanophases were studied by AES, EELS, AFM and conductivity measurements during MBE deposition of Fe and Co on Si(100) and (111), respectively. AES data demonstrated a layer by layer growth of Fe with a segregation of submonolayer coverage of Si at T = 20 °C and, after annealing at T = 250 °C, a fixed and increased value of the Si-to-Fe Auger-peak ratio in the ranges of d = 0.03−0.12 or 1.2 nm and 0.3−0.6 nm, respectively. EELS spectra indicated a redistribution of valence electrons at the Fe/ Si(100) interface at d = 0.03−0.12 nm. With further increase of Fe thickness, EELS spectra showed transitions to Fe nanophases with lowered concentration of valence electrons near d = 0.12−0.3 nm and d = 0.6−1.2 nm. After annealing AFM images showed the relief stability of stepped Si(100) surface in the range of d = 0.03−0.3 nm, the disappearance of the stepped relief type after 0.3 nm and formation ridge-like islands in Fe film at d = 1.2 nm. Auger peak intensity and conductivity versus the thickness for nanophases of Co on Si(111) showed variations of growth mechanism in accordance with variations of interface layer state.

The results of complex investigations of the crystalline structure, composition and specific magnetization of the multi-wall carbon nanotubes (CNTs) filled by magnetic nanocomposite are performed. CNT arrays have been synthesized by the high temperature pyrolysis of fluid hydrocarbon - p-xylole [C₈H₁₀] in the presence of volatile catalyst - ferrocene [Fe(C₅H₅)₂] at the walls of tubular-type quartz reactor of specially constructed equipment. It was revealed that the obtained CNTs constitute complex nanocomposite: C - Fe₃C - Fe₅C₂ - Fe. The magnetic properties of such CNTs in the temperature region of 78≤T≤1060 K are conditioned by the ferric carbide (in the form Fe₃C H Fe₅C₂) and Fe.

Influence of ultra-violet radiation of the KrF laser (wave length 248 nm, pulse duration 20 ns) on atomic structure of amorphous vanadium pentoxide thin films, prepared by the pulsed laser deposition method, is studied. Calculations of the short-range order characteristics (radii and diffusiveness of coordination spheres, coordination numbers) were performed by the Finbak -Warren method. It is established that minimal structure unit of amorphous V₂O₅ film before and after irradiation is a strongly deformed oxygen octahedron. Distortions of tetragonal pyramids in the initial and modified film are different. Also, oxygen deficiency in a tetragonal pyramid is observed.

Low-resistance ohmic or Schotky contacts between diamond and metal is primary goal of electronic devices and microsystems based on diamond. The contact resistance depends not only on the choice of metals but also on annealing, layer thickness and other parameters. Combination of titanium, platinum and gold (with co-deposited gold on top to prevent oxidation) is most widely used and yields to good conductivy after being annealed. Diamond films were grown by Microwave Plasma (MP) and Hot Filament Chemical Vapor Deposition (HF CVD) on Si substrates. The dependence of electrical properties on the film morphology was studied. The surface morphology of grown layers was analyzed by scanning electron microscopy (SEM). The different crystallographic character of diamond layers, i.e. either polycrystalline or nanocrystalline, was achieved by using different deposition conditions. Lower-quality diamond films were less sensitive to variation in the operating conditions. The film break-down voltage and other electrical parameters strongly depend on the morphological character, the grain size and defects in layers.

A ferromagnetic nanocomposite consisting of metal-structures enclosed in a porous silicon skeleton is investigated magnetically by SQUID-magnetometry and the structural examination is performed by SEM. The ferromagnetic nanostructures are achieved by chemical deposition of Ni or Co from an adequate metal-salt electrolyte. The deposited Ni-nanostructures are restricted to the highly oriented pores of an aspect ratio up to 1000 and therefore the samples show a strong magnetic anisotropy between easy axis and hard axis magnetization, respectively. In the field range below 1 T the observed anisotropy is mainly caused by shape anisotropy of the Ni- nanostructures (spheres and elongated particles). It enhances with the amount of needle-like shaped nanoparticles exhibiting a length of a few micrometers which fill the pores successively over the entire depth of the porous layer of about 30 μm. Magnetization measurements exhibit strong temperature dependence between 4.2 K and 300 K. At low temperatures the samples do not get saturated with the available magnetic fields of 7 T but give rise to a paramagnetic behavior due to orbital magnetism. This additional magnetic behavior to the known ferromagnetic property is due to the enhanced orbital magnetic moment at surfaces compared to the spin moment. The orbital moment can be associated to the spin polarized states at the surface of the metal-particles which are less bound due to a reduced exchange interaction. The change in the magnetic behavior between the usual mere ferromagnetic character and the supplementary paramagnetic behavior is only observed for magnetic fields perpendicular to the sample surface.

We have considered stable magnetic ordered structures on two-dimensional ion lattice with spins and states of delocalized charge carriers in these magnetic structures. These magnetic structures have short-range ferromagnetic order and long-range antiferromagnetic order. Besides magnetic momenta there are additional momenta with symmetry of the orbital momentum. Each of these inhomogeneous magnetic configurations is topologically stable and is characterized by their own field topological number q and a finite energy E^q. As a result, these inhomogeneous configurations can exist at sufficiently high temperatures, for example, in classical (lanthanum, yttrium) high-temperature superconductors. These ion-field magnetic structures are not collapse because of interactions with current carriers. However, the charge carrier states are determined by structure of magnetic configurations. The energy functional of the charge carrier system is finite and single-valued only if the charge carrier system is coherent and has conserved momenta, whose symmetry is consistent with the structure of the ion-field configurations. We have found coherent charge carrier p-and d-states, and d-states have superconducting properties, but p-states can exist above the crinical temperature T_c.

We develop a path-integral theory to study the angle-resolved photoemission spectra (ARPES) of high-T_c superconductors based on a two-dimensional model for the CuO₂ conduction plane, including both electron-electron (e-e) and electron-phonon (e-ph) interactions. Comparing our result with the experimental one of Bi₂Sr₂CaCu₂O₈, we find that the experimentally observed isotopic band shift in ARPES is due to the off-diagonal quadratic e-ph coupling, whereas the presence of e-e repulsion partially suppresses this effect.