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The modification of gold surfaces with scanning tunneling microscopy in ultrahigh vacuum was investigated. At a tunneling resistance higher than 1 GΩ, a hole was created by applying a negative voltage pulse to a gold tip, and a mound by a positive one. The existence of a critical field together with the polarity dependence suggests that a mechanism of the modification would be the field evaporation of positive Au ions. On the other hand, at a low resistance, a mound adjacent to a hole was often created by the negative pulse and the current kept flowing even after the voltage pulse. These results indicate that the formation of a mound in the case of negative pulses is a result of necking after the massive transfer of gold from the surface to the tip apex. The size of the hole created by applying the negative pulse with the threshold voltage decreased as the initial tunneling resistance decreased.

Force microscopy techniques such as atomic force microscopy (AFM), friction force microscopy (FFM), and force modulation microscopy (FMM) were applied to polymer blend and copolymer surfaces to observe phase-separated structures and distinguish the individual components. We observed a continuous phase-separated structure of polystyrene (PS)/polyethyleneoxide (PEO) polymer blend, a micro-phase-separated structure of styrene (S)/butadiene (B) S-B-S-B block copolymer, and islands-sea phase-separated structures of PS/polymethylmethacrylate (PMMA) polymer blend and diblock copolymer with AFM. FFM and FMM were applied to PS/PMMA polymer blend and diblock copolymer, and FFM differentiated PS from PMMA.

Adsorption and photochemical decomposition of triethylgallium [Ga(C2H5)3] on Si(111) at room temperature were investigated by means of low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), scanning tunneling microscopy (STM) and mass spectroscopy (MS). Ga(C2H5)3 was adsorbed on Si(111) until its saturation, at which point LEED and STM indicated disordered adsorption of the molecules. Irradiation of ultraviolet light onto the Ga(C2H5)3-saturated surface caused carbon incorporation contrary to the case of pyrolysis. Ethyl species were proposed to result from the photon absorption processes of the molecules.

Atomically flat substrates of gold were prepared by evaporation onto cleaved mica for scanning tunneling microscopic and spectroscopic studies of adsorbates. The surface morphology was investigated with a scanning tunneling microscope (STM) and a scanning electron microscope. The STM data were analyzed through a fractallike statistical procedure. Bulk crystallography was also investigated by means of X-ray diffraction. On the gold substrate showing hydrophilic characteristics, monolayer Langmuir-Blodgett film of cadmium arachidate was deposited, and successfully imaged by STM.

It is reported that small pits are made in a graphite surface by applying voltage pulses using a scanning tunneling microscope (STM). A shallow hole, whose diameter was about 10 nm, was formed by creating the pits along the circumference of a circle. The depth of the hole was about 0.35 nm, which is very close to the interlayer distance of graphite. The result indicates the possibility of cutting a piece of layered material by monolayer thickness using an STM. The chemical process of pit formation is discussed.

Molecules of liquid crystals adsorbed on graphite were observed by scanning tunneling microscopy (STM). Liquid crystals of both smectic and nematic phases provided periodic STM images of 3-nm-spacing lines, seemingly composed of molecules with their axes vertical to the line. Detailed investigation of the images revealed that several different patterns existed in smectic liquid crystal. On the other hand, nematic liquid crystal exhibited one reproducible pattern. Monolayer, multilayer, and dimer-based molecular arrangements are discussed. Models for the molecular arrangement of the nematic liquid crystal are proposed.

The scanning tunneling microscope (STM) was invented less than five years ago by G. Binnig and H. Rohrer. In 1986 they were honored with the Nobel prize in physics, together with E. Ruska who invented the transmission electron microscope in 1933. The principles of the STM and the construction of the instruments are described by dividing them into several key technologies: (i) vibration isolation; (ii) course and fine positionings and scannings; (iii) thermal drift, hysteresis, and creep of piezoactuaters; (iv) metal probes; and (v) electronic control circuits. Surface structures recently observed by the STM on metals, semiconductors, etc. are reviewed. The future development of the STM is mentioned very briefly.

Vibration isolation technology for scanning tunneling microscopy (STM) to suppress the external mechanical perturbation down to a subatomic scale is described. The system is simplified into two subsystems, a tunneling assembly and a supporting table. Each of them has its own mechanical eigenfrequency. The principle of the isolation exists in making the two eigenfrequencies very different from each other. A theory of isolation developed is based on a model of multiply coupled oscillators with damping. Experimental results of the isolation characteristics for the two types of isolators constructed, one consisting of two‐stage coil springs and the other of multiply stacked metal plates with rubber pieces among them, are well explained by the theory. STM images of graphite are obtained by using these isolators combined with various tunneling assemblies. Thereby the basis for design of the isolators is clarified.

A helium refrigerator system equipped with low-temperature centrifugal compressors is proposed. This refrigerator, named L-system refrigerator, is operated almost below the temperature of liquid nitrogen. It has higher reliability and capability of long time continuous operation free from the contamination of helium with oil and from wear of moving part. It also has an advantage that the control of refrigeration power is easily achieved by adjusting the speed of compressors. The direct input power to the L-system refrigerator is lower, but it thermal efficiency is almost same as the conventional one, when the energy necessary to make liquid nitrogen is taken into account.A L-system refrigerator with refrigeration power of 1, 500W at 20K level is designed based on the experimental results of the low-temperature centrifugal compressor developed at Electrotechnical Laboratory. Its refrigeration power at 20K varies from 930W to 2, 000W almost lineary by changing the rotational speed of the compressors from 500rps to 720rps. The direct input power is 17kW to 35kW, but it consumes 310kg to 630kg of liquid nitrogen par hour.Large capacity helium refrigerators with high reliability and efficiency will be materialized when L-system refrigerators are built near the region where a large bulk of coolant is easily obtained, such as a LNG repository.

A small‐size scanning tunnel microscope (STM) developed to provide an easy operation for both tip and sample setting is applied to three‐dimensional topographic measurements of microlithography patterns. The patterns having a grid structure with 160 nm in periodicity, 20–30 nm in groove width, and 40–50 nm in groove depth are fabricated on Si substrates using a technique of enhanced chemical etching by focused ion beam. The STM images are compared with two‐dimensional scanning electron microscope images. Fairly good resolution of topographic maps for a large area is obtained for the fine groove structures. The large‐area images are further processed to correct the piezoscanners’ nonlinearity, which becomes conspicuous for large‐area scanning.

SUMMARY Investigations of charge-density waves (CDW) in 4Hb-TaS2 and the shifted Fermi level in a CoCl2 graphite intercalation compound (GIC) were performed by scanning tunnelling microscopy (STM) and scanning tunnelling spectroscopy (STS) A discrimination of the surface electronic structure of the octahedral structure and of the trigonal-prismatic structure in 4Hb-TaS2 was made successfully in terms of the electronic properties. The measured value of the charge-density-wave gap in 4Hb-TaS2 at room temperature was about 85 meV. The shifted Fermi level in CoCl2-GIC was measured to be about 400 meV.

SUMMARY As a sample for initial study on biological materials by using scanning tunnelling microscope (STM), we selected phosphoric acid consisting of phosphorous atoms which play biologically an important role. We measured polyphosphoric acid coated on HOPG by STM and scanning tunnelling spectroscopy (STS) in air. In order to identify molecules on STM images, local I-V curves were taken simultaneously. The averaged I-V curves and the normalized conductance spectra of graphite coated with the acid show characteristics different from those of clean graphite surface. Around a step of the substrate, we found domains where normalized conductance spectra were different from those of clean graphite surface and ascribable to that of the adsorbed molecules.

Simultaneous measurements of scanning tunneling spectroscopy (STS) and scanning tunneling microscopy (STM) are performed on HOPG and 2H–NbSe2 in air. In order to see the distribution of local density of states related to different atomic sites and species STS images of normalized differential conductance are mapped. Correlation function between the STS images and corrugation in corresponding STM image is obtained as a function of the tip bias voltage.

Centrifugal helium compressors were developed to improve efficiency and reliability of helium refrigerators. These comprssors are operated almost below the temperature of liquid nitrogen. The rotor of the compressor is supported by helium lubricated gas bearings. A controlled attractive magnetic bearing is adoptted as auxiliary.Two compressors were manufactured. The 1st. trial one was made simply for experiment to study the possibility of low-temperature helium compressors. The 2nd. trial one was made taking practical use into consideration in respect to flow rate and compression ratio.This paper describes mainly the 2nd. trial compressor. Its typical specifications are as follows: type: two-stages centrifugal compressor with intercooler, flow rate: 75g/s, total compression ratio excluding the pressure loss in intercooler: 1.69, inlet helium temperature: 80K, rotational speed: 700rps (42, 000rpm), motor output: 10.2kW, type of bearings: helium lubricated internal tilting pad radial bearings and a spiral grooved thrust bearing with a controlled attractive magnetic bearing.The compressor was installed in a vacuum chamber for cold test, and the performance was examined in a closed loop. Items to be measured are rotational speed, electric input power, flow rate, pressure and temperature of helium gas at each inlet and outlet ports, vibration of the rotor and the current of the magnetic bearing. The results showed that the compressor excelled the expected values in performance. The following is the principal performance at the rated rotational speed, total compression ratio at the flow rate of 74.8g/s: 1.76, adiavatic efficiency: 1st. stage; 71%, 2nd. stage; 73%, total efficiency: 62%. The rotor supported by the bearing above mentioned operated stably up to 44, 000rpm. The controlled attractive magnetic bearing gave an adequate clearance to the thrust gas bearing in start and stop condition, so that the rotor was able to start many times without any damage to the gas bearings. The compressor has operated for a long time.

Conventional roll forming processes for electric-resistance-welded (ERW) pipes are outlined with respect to roll contours, stand arrangements and deformation strains during forming. The developmental history and features of a new process (VRF process) for forming ERW pipes by constraining the strip edges with undriven vertical rolls are described. The equipment characteristics, fundamental forming characteristics and forming load characteristics of the new process are compared with those of the conventional ER W pipe roll forming processes. Neutral line constant as pass line and uniform displacement distribution as forming distribution are found to be the optimum combination for the VRF process. The results of the present study show that this process can reduce edge stretch and forming energy, and is expected to save roll, equipment and energy costs when put to commercial use. The dimensional tolerances of pipe products manufactured in preliminary commercial production experiments are also described.

The atomic image of 2H-NbSe2 surface was successfully recorded with a scanning tunneling microscope (STM) at room temperature. The trigonal pattern of the image is in good agreement with the results of the X-ray diffraction experiments. The STM apparatus developed here showed resolutions of 0.3 nm in the lateral scale and 0.05 nm in the vertical scale.

We have demonstrated that nanostructures of self-assembled monolayer (NSAM) films of alkanethiols can be formed on the GaAs surface of a AlGaAs/GaAsheterojunctions by cleaving the substrates in an octadecylthiol solution diluted with ethanol. NSAMs with line width as narrow as 5 nm were observed by phase imaging using tapping mode cross-sectional atomic force microscopy (TMXAFM). Time dependent observation of the surface in air revealed that the nanostructual formation occurred as a results of both selective chemisorption of alkanethiol on GaAs surfaces and the oxidation of AlGaAs surface.

We succeeded in observing individual single-walled carbon nanotubes (SWNTs) using an atomic force microscope (AFM) in the tapping mode by paying attention to the preparation of both samples and AFM tips. To disentangle the bundles of SWNTs, we added a small amount of amine into N,N-dimethylformamide. To achieve a high resolution in tapping-mode AFM imaging, we used carbon nanotube (CNT) tips whose radii could be reduced. We were able to image individual SWNTs using CNT tips with widths that were half of those imaged using conventional silicon tips. With this improved resolution, we could clearly resolve the two SWNTs lying parallel on a mica substrate.

Self-assembled nanometer-scale wires (SANWs) composed of octadecylthiol [ODT, CH3(CH2)17SH] have been selectively formed on the GaAs surface of an AlGaAs/GaAs heterostructure. The sample grown by metal organic chemical vapor deposition (MOCVD) was cleaved to expose the AlGaAs/GaAs heterostructure in a solution containing the ODT molecules. Both surface properties and morphology of these wires have been investigated simultaneously by scanning probe microscopy. SANWs as narrow as 10 nm in width and ∼1.0 nm in height were observed. The inability to form an ODT monolayer on the AlGaAs surface was attributed to the formation of an oxide layer.

Scanning force microscopy (SFM) was successfully used to study the microstructures of acrylic polymer-silica nanocomposite surfaces processed by the sol-gel method. We observed excellent flatness of the dip-coated nanocomposite surfaces (root mean square roughness = 0.345 nm; mean roughness = 0.270 nm), probably due to the levelling effect of the dipping solution. SFM revealed that acrylic polymer and silica were hybridized on surfaces, with domain sizes from several to 30 nm, where friction forces between silica and acrylic polymer against the Si3N4 SFM tip were 35 and 1.6 nN respectively, for a 0.1 nN load.

An investigation of charge-density waves in 4Hb–TaS2 was carried out by scanning tunneling microscopy and scanning tunneling spectroscopy. We succeeded in discriminating of the surface electronic structures of 4Hb–TaS2, octahedral structure and trigonal-prismatic structure in terms of the electronic properties. The measured energy gap of the charge-density waves of 4Hb–TaS2 at room temperature was about 9± 10 meV.

A scanning tunneling microscope (STM) with a capability of spectroscopic measurement for operation for 300 K to 1.2 K was constructed. Measurements of the current-voltage characteristics (I-V's) were performed on 2H-NbSe2 and a high-T c superconductor Y-Ba-Cu-O. Spatial variations in the local density of states (LDOS) relevant to the low temperature phases, CDW and superconductivity, were extracted from data statistics.

We have measured very thin films of copper phthalocyanine on graphite by means of scanning tunneling microscopy (STM) and spectroscopy (STS) in air. Microscopic surface structures, such as islands and grains, were found by STM. Among them, a sticklike island, with its edge parallel to the graphite lattice, suggested the epitaxial growth of the deposited film. Although the individual molecular shapes could not be obtained clearly, tunneling spectra taken simultaneously with STM provided information about the local distribution and orientation of the molecules.

Anomalously large surface corrugation of 2H-NbSe2crystal was observed by scanning tunneling microscopy (STM). Besides mounds representing the Se atoms, hollow sites and Nb-atom sites clearly appeared as dips and saddle points, respectively. The lateral resolution was proved to be better than 0.2 nm. The large corrugation amplitude was attributed to the effect of atomic force between the tip and the sample.

Langmuir-Blodgett films of cadmium-arachidate have been studied by scanning tunneling microscopy (STM). Substrates of gold and graphite are used to make mono- and bilayer films. The image of the individual molecule cannot be obtained for the films on gold, but the data indicate disturbances on the tunneling current caused by the films. As for the films on graphite, the molecular images with a spacing of 0.4–0.7 nm are recognized in some frames of the variable tunneling current image recorded on videotape. Possible mechanisms of the imaging are discussed.