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The adsorption process, molecular arrangement and protonation behavior of self-assembled monolayers (SAMs) of bipyridine thiol on Au(1 1 1) were investigated using X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM), with a view towards constructing a molecular ion sensor. When the bipyridine SAMs were immersed in a strong CF 3 SO 3 H solution for protonation of the bipyridine group, additional N(1s) XPS peaks were generated at higher binding peak positions where the origin of the peak was considered to be the N–H species. We further investigated the relationship between the immersion time for the SAMs and the probability of protonation. We observed a decrease in the probability of protonation with a longer immersion time for the SAMs. We consider that both the bipyridine molecular arrangements and the molecular density on the Au surface are crucial for controlling the probability of protonation based on the STM and XPS data.

We investigated the use of a single treatment of estradiol benzoate (E2B) to prevent pregnancy in mismated dogs, including effects of dose, side effects, and mechanism of action. We used 74 female beagles aged 1-10 year. A single treatment of E2B (0.025, 0.05, 0.10, or 0.20 mg/kg; 10 dogs/dose) given 2 days after mating (5 days after ovulation) resulted in pregnancy rates of 70, 50, 10, and 0%, respectively, whereas pregnancy rate was 100% in 5 untreated (control) dogs. There were no side effects in dogs given E2B, regardless of dose. To clarify the mechanism of prevention of pregnancy, we investigated embryonic descent in the uterine tube and embryonic degeneration after treatment with 0.025 or 0.20 mg/kg of E2B; treatment delayed embryonic descent in the uterine tube and increased the incidence of embryonic degeneration. In conclusion, a single treatment of 0.020 mg/kg of E2B given 2 days after mating effectively and safely prevented pregnancy in dogs.

Surface potential switching on gold(111) surfaces is induced by complexation/decomplexation reactions of a bipyridine (BP) derivative and palladium(II) chloride, as observed by Kelvin probe force microscopy (KFM). On the basis of the theoretical predictions, a 4-(5-phenylethynyl-2,2'-bipyridine-5'-yl-ethynyl)benzenethiol (PhBP) derivative was synthesized and used as an active monolayer to catch transition metal ions. By using the microcontact printing (CP) technique, micron-size patterned PhBP monolayers, which act as effective hosts to coordinate palladium(II) chloride, were prepared on gold(111) surfaces. The KFM signal decreases by complexation of the Pd(II) chloride in PhBP monolayers and is recovered by removal of Pd ions using an ethylenediamine solution, as confirmed by X-ray photoelectron spectroscopy. This process is reversible, indicating that the surface potential switching is realized by complexation/decomplexation of Pd(II). A CP PhBP monolayer, when it detects the target palladium ion, shows sensitivity for the picomolar level detection judged from surface potential changes in KFM measurements. The dipole moment estimated by the surface potentials is much smaller than the calculated value, indicating that mechanisms for the reduction of the surface dipole moment exist in real monolayers prepared by the CP method.

We have developed a fabrication method for nanogap electrodes without employing photo- or electron-beam lithography to measure the electrical characteristics of nanostructured molecules. This angle-controlled shadow-masking method enables us to construct nanogap electrodes without a wet process after the molecules are positioned on the substrate. The proposed method makes it possible to measure electrical characteristics without structurally deforming or denaturing the molecules due either to the step edge of an electrode or to the organic solvents used in the wet process. The results demonstrate that a gap length between the electrodes of less than 100 nm can be fabricated reproducibly. We have measured the electrical characteristics of lambda DNA (λ-DNA) networks and molecular nanorods made of porphyrin-derivative molecules (TPPS: 5,10,15,20-tetraphenyl-21H,23H-porphyrine tetrasulfonic acid) in which J-aggregates are formed inside. Experimental findings reveal that the electrical conductivity of λ-DNA decreased under a vacuum condition, whereas that of TPPS nanorods decreased under oxygen and nitrogen gas-purged conditions.

All-trans oligo(para-phenylenevinylene) (OPV) methyl thiols of a two-ring phenylene-vinylene dimer and a three-ring trimer have been synthesized to prepare self-assembled monolayers (SMS) onto an Au(1 1 1) surface. The molecular level morphologies of the monolayers prepared on Au surfaces were probed by scanning tunneling microscopy (STM) or atomic force microscopy (AFM). The soluble dimer formed a highly ordered structure lying down on the Au surfaces. The molecules of trimer stand slantwise on the Au surfaces, but the structure of monolayers is less ordered. Another longer OPV methyl thioacetate, a slightly soluble four-ring tetramer, has also been synthesized. Although it was difficult for aggregative molecules of the longer OPV to self-assemble on Au, we could successfully insert the tetramer into tetradecane-1-thiol monolayers on Au surfaces by an exchange reaction. The mixture monolayer showed that the isolated tetramer was adsorbed almost vertically on the Au surfaces.

The electrical conduction of self-assembled monolayers (SAMs) made from conjugated molecules was measured using conductive probe atomic force microscopy (CP-AFM), with a focus on the molecular structural effect on conduction. First, the electrical conduction of SAMs made from phenylene oligomer SAMs was measured. The resistances through the monolayers increased exponentially with an increase in molecular length and the decay constants of transconductance beta were about 0.45 to 0.61 A(-1) measured at lower bias region. We further investigated the influence of applied load on the resistances. The resistances through terphenyl SAMs increased with an increase in the applied load up to 14 nN. Second, using an insertion technique into insulating alkanethiol SAMs, the electrical conduction of single conjugated terphenyl methanethiol and oligo(para-phenylenevinylene) (OPV) molecules embedded into insulating alkanethiol SAMs were measured. Electrical currents through these single molecules of OPVs were estimated to be larger than those through single terphenyl molecules, suggesting that the OPV structure can increase the electrical conduction of single molecules. Third, apparent negative differential resistance (NDR) was observed at higher bias measurements of SAMs. The appearance of NDR might be related to roughness of SAM surface, because apparent NDR was often observed on rough surfaces. In any case, the tip-molecule contact condition strongly affected carrier transport through metal tip/SAM/metal junction.

Oligo(para-phenylene-vinylene)-methanethiol of trimer and dimer have been synthesized to prepare monolayers onto Au(111). The trimer diluted in dichloromethane glows with a brilliant blue fluorescence when excited with UV light (365 nm). The absorption and emission spectra of the dimer diluted in CH 2 Cl 2 show a blue shift. The molecular level morphologies of the monolayers prepared on gold surfaces were probed by scanning tunneling microscopy or atomic force microscopy (AFM). The dimer is entire trans isomer, which formed highly ordered self-assembled monolayers (SAMs) on Au. The trimer is a mixture of cis–trans isomers, and did not form ordered monolayers on Au. However, the trimer molecules could be embedded in dodecanethiol SAM, and showed higher conductance than oligo(para-phenylene) molecules characterized using a conductive AFM.

Polyyne-containing carbon has been shown to be converted to carbon nanotubes (CNTs) and carbon onions by irradiating an electron beam. The carbon, which is prepared by a reduction of poly(tetrafluoroethylene) (PTFE), is unstable, reactive, and it is used as a precursor to form carbon nanostructrues. A precise transmission-electron-microscope (TEM) observation reveals that some nanostructures, fibrous and spherical, are already formed in the carbon before the irradiation. The nanostructures are assumed to be formed during the reduction of PTFE. The spherical carbon is well graphitized, whereas the fibrous is not. The reduction is carried out at 0 °C, which is not enough for the fibrous carbon to be well graphitized. The findings suggest a possibility to form a CNT without an electron beam via a reactive polyyne precursor, and are expected to lead an as-designed CNT synthesis.

An unusual penta-peptide nanotube was synthesized by a solid-phase method using Fmoc chemistry. This nanotube consists of the natural homo-L-amino acid sequence (cyclo[-(L-Gln)5]), which is different from the already-known dl-peptide nanotubes having an even number of residues. We also observed the morphology by atomic force microscope (AFM) and found meandering tubular structures on the substrate. This result is consistent with our ab initio energy calculations, which show that the penta-peptide nanorings stabilize by breaking the C5 symmetry and stack themselves to form a meandering nanotube through the inter-ring hydrogen bonds.

Rotaxane (R4) molecules coupled with a lipoic acid moiety, which contains a disulfide group, have been fixed on evaporated Au films. R4 molecules have been coadsorbed with n-hexanethiol (C6SH) from solutions of methylene chloride to form self-assembled monolayers (SAMs). X-ray photoelectron spectroscopy reveals that two-component SAMs were rapidly formed within 1 h, while further immersion of more than 1 h caused a gradual decrease in the amount of R4 molecules in the mixed SAMs. This observation indicates that the R4 mole fraction in SAMs (Χ S A M ) was primarily governed by the adsorption kinetics of both R4 and C6SH. Then we attempted to control Χ S A M of the mixed SAMs by changing the R4 mole fraction of the solutes in solution (Χ s o l ). Infrared spectroscopy and tapping-mode atomic force microscopy (TM-AFM) were conducted to estimate the Χ S A M values of the two-component SAMs. We compare the experimental relations between Χ s o l and Χ S A M with model functions in connection with the adsorption kinetics. One of the models, in which desorption of C6SH species obeys second-order kinetics, well describes the experimental results in a wide domain (10 - 7 ≤ Χ s o l ≤ 1). This agreement between the model and the experimental results suggests that adsorbed C6SH can be desorbed as disulfide and that protrusions observed by TM-AFM are most likely isolated single R4 molecules.

We investigated an annealing effect of self-assembled monolayers (SAMs) generated from derivatives of terphenylmethanethiols and tetradecanethiol (C14) on Au(111) using scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy, and contact angle measurement. STM data revealed that the molecules were partially desorbed by the annealing process at temperatures where the contact angle of the hexadecane began to decrease. The decreases in contact angles of both the CF3- and CH3-terminated terphenyl SAMs were caused by annealing at 180 °C for 1 h, while a similar decrease began at a lower temperature of 150 °C in the C14 SAMs. From the STM data, a large amount of CH3-terminated terphenyl molecules remained after annealing at 180 °C for 3 h, while a small amount of molecules were observed in the other two SAMs. These data demonstrate that the CH3-terphenyl-derivatized thiol SAM had the highest thermal stability of the three SAMs, and the molecular backbone structure and end group were crucial for de...

We have studied the phase-separation of self-assembled monolayers (SAMs) of dialkyl disulfides on Au surface. Initially, the heat-induced phase-separation of SAMs consisting of unsymmetric disulfide molecules (CF 3 (CF 2 ) 5 (CH 2 ) 2 SS(CH 2 ) 7 CH 3 ) of hydrocarbon and fluorocarbon chains was investigated. We proved that the dimer structure cleaved on the Au surface. Subsequently, we formed one-dimensional nanostructures utilizing an anisotropic phase-separation of SAMs consisting of a mixture of the above unsymmetric disulfide and a symmetric disulfide of hydrocarbon (CH 3 (CH 2 ) 7 SS(CH 2 ) 7 CH 3 ). The wire-like structure with a width of 5 nm and a length ≈100 nm was observed by scanning tunneling microscopy.

We synthesized soluble rod-like silylthiophene, silylbithiophene, and silylquaterthiophene derivatives with various functional groups. Their self-assembled monolayer films on silicon oxide were evaluated by atomic force microscopy, X-ray photoelectron spectroscopy, water contact angle measurements, and fourier transform infrared-reflection absorption spectroscopy. We found that the molecular density (molecules/area) of the resultant films increased with thiophene moiety. This is probably due to the effective π-stacking of aromatic rings between molecules.

The formation process of an alkylsiloxane self-assembled monolayer (SAM) on silicon oxide produced under various conditions was investigated. The growth rate of octadecyltrichlorosilane (OTS) SAM was dependent on the moisture level in the oxidation system. Area-selective oxidation of a silicon substrate with a native oxide layer was carried out under controlled humidity conditions by the field induced oxidation (FIO) technique using an atomic force microscope with a conductive cantilever. The silicon substrate partly FIO oxidized under dry nitrogen was immersed into the OTS solution, and the contact angle and topographic image showed that the OTS layer was formed only on the native oxide. In contrast, when the FIO was performed under a humidity of 88%, OTS SAM was formed both on FIO and native oxides. These results indicate that SAM formation on silicon oxides can be locally suppressed by FIO in a dry environment. Using this technique, we could fabricate an OTS SAM line structure as narrow as 22 nm.

Phenylene ethynylene dithiol derivatives containing a bipyridine ligand along the conjugated system were introduced between nanogap electrodes, and significant conductance changes of the bridging molecules were observed upon complexation with Pd(II).

Atomic force microscopy has been successfully used to observe morphologies and characterize polymer components of poly(styrene-block-ethylene/butylene-block-styrene) (SEBS) triblock copolymer surfaces. The surfaces exhibited characteristic topographies consisting of hills and valleys. The height difference between them increased with the polystyrene component, which is probably due to the stress increase between two phases. The surface area fraction of the hills also increased with polystyrene component, and the local stiffness of the hills was higher than that of the valleys. These results indicate that the hills correspond to polystyrene and the valleys to rubbery poly(ethylene/butylene). The morphology of polystyrene changed from long worm-like to mesh-like structures with increasing polystyrene content in the block copolymers and exhibited a moniliform-like structure with a periodicity of 20–30 nm. These structures may be caused by surface segregation of the polystyrene component in the block copolymer surface.

The techniques of scanning force microscopy have been successfully used to investigate phase-separated polymer surfaces on a nanometer scale and been proved to be of great advantage in surface characterization studies of polymers. We observed two kinds of phase-separated surfaces of polystyrene (PS)-polyethylene oxide (PEO) blend film and injection molded crystalline engineering polymer (acetal resin)-elastomer blend plate. In the local mechanical property measurement of the PS-PEO samples, PEO domains were found to be softer and show higher friction force than PS domains with the lateral resolution of less than 100 nm. The results agree qualitatively with those of the bulk. In the local friction measurement of the acetal resin-elastomer blend plate, the surface showed stripe structures 100–300 nm wide: the lower friction region corresponds to acetal resin and the higher one to elastomer. However, in the local elasticity measurement, the difference between the two could not be detected presumably due to the subsurface effect.

Local elasticity was measured on polymers by modifying atomic force microscopy (AFM) in which the sample height was modulated and the response of the cantilever was detected. In a case of polystyrene (PS) on mica, there existed many circular holes in the film that were stiffer than the rest parts. The holes were identified as the substrate mica surface and the rest as PS films. In the case of a polyethyleneoxide surface on mica, a crystalline nature was observed. In addition, the surface was modified by scanning an AFM tip at large forces of 20 nN. The scanned area exhibited an increase in elasticity as well as formation of a striped structure.

We observed molecular resolution images of dibutylamino-triazine-dithiol films on Au(111) with scanning tunneling microscopy. In contrast to the more extensively studied alkanethiols which have only one binding site, the triazine-dithiol has two possible binding sites. The periodic structure of bright spots with different shapes and contrast aligned along the 〈112〉 directions with a spacing of 0.75 nm and 1 nm were imaged. The domain size of the film is 15 nm at most, which is considerably smaller than that of alkanethiol films. The structural stability upon annealing indicates a stronger binding energy of the triazine-dithiol as compared with the alkanethiol. We propose models of the molecular arrangement assuming that the two sulfur atoms of the molecule bind to the substrate.

The surfaces of silica-based sensor chips, designed for evanescent-field-coupled waveguide-mode sensors, were functionalized using various surface chemistries. The immobilization of molecular entities on the functionalized silica surfaces was monitored using various microscopic techniques (scanning electron, fluorescence, and atomic force microscopies). Further, gold nanoparticle-based signal enhancement analyses were performed with protein conjugation on different functionalized surfaces using a waveguide-mode sensor. Based on these analyses, the sensor surfaces modified with glutaraldehyde (Glu) and carbonyldiimidazole were found to be good for molecules of different sizes. In addition, it can be inferred that the Glu-modified surface may be suitable for small molecules with diameters around 5 nm owing to its surface roughness. The modified surface with carbonyldiimidazole is suitable for the direct immobilization of larger molecules especially for biomolecular assemblies without intermediate chemical modifications.

A selective formation between carbon nanotubes (CNTs) and carbon nanoparticles (CNPs) has been found, where polyyne-containing carbons are heated and irradiated by an electron beam in a transmission electron microscope. The CNPs are formed outside the polyyne-containing carbons that are partially damaged by water and oxygen, while the CNTs, inside the carbons that are protected. This gives insight on a CNT and CNP formation mechanism, which is discussed in this paper.

Scanning force microscopy (SFM) images of the surfaces of poly(ethylene oxide) (PEO) crystals revealed oriented fibril-like growth with increasing annealing temperature. Some clear nucleation centres on the melt-crystallized surface and typical lamellar morphologies with a step height of 11.7 ± 0.5 nm were observed. Molecular folding structure (near-four-fold symmetry structure with the nearest neighbour spacing of 7.4 A) was also imaged on the PEO single crystal with SFM. The spacings and angles of the periodic array in the molecular image were consistent with the positions of the top of the molecular chain folds on the PEO single crystal surface.

Many methods were developed to image DNA by AFM both in ambient conditions and under physiological ones. The main difficulty in physically mapping DNA molecules is that they exist as random coils. Such conformation makes it difficult or impossible to obtain quantitative structural information especially when a DNA fragment longer than several thousands bases is used. Using a very low concentration of silane to introduce limited number of amino groups to the surface was a key point in fine tuning the crosslinking reaction without strongly adsorbing DNA to the surface. Such treatment allowed stretching the tethered molecules in one direction.

An efficient method was developed to stretch DNA molecules on an atomically flat surface for AFM imaging. This method involves anchoring DNA molecules from their 5' ends to amino silanized mica surfaces. N-Succinimidyl6-[3'-(2-pyridyldithio) propionamido]hexanoate (LC-SPDP), a heterobifunctional cross-linker with a flexible spacer arm was used for this purpose. Immobilization was carried out by introducing a thiol group to the 5' end of DNA by PCR. Thiolated molecules were then reacted with the cross linker to conjugate with its 2-pyridyl disulphide group via sulfhydryl exchange. The resulting complex was deposited on amino silanized mica where NHS-ester moiety of the cross linker reacted with the primary amino group on the surface. Samples were washed by a current of water and dried by an air jet in one direction parallel to the surface. DNA molecules were fully stretched in one direction on imaging them by AFM.

We observed polymer blends and copolymer surfaces with force microscopy. Multi-component polymer surfaces exhibit characteristic morphology due to the phase separation. In order to distinguish the components in the pattern, we made a lateral force measurement and a compliance measurement in addition to the normal force microscopy. Films made from a mixture of polystyrene (PS) and polymethylmethacrylate (PMMA) exhibited circular hillocks with a diameter of 500-2000 nm. The lateral force was smaller on the hillocks by about 1.6 nN than on the other area. The difference in the hardness between the two region, however, was below the detection level. Since the PMMA used has larger surface tension than the PS, we have concluded that the hillocks are made of PMMA. We measured also polyethyleneoxide (PEO) and its mixture with PS. Pure PEO was crystallized by a thermal treatment and exhibited spiral growth morphology with a step height of 7-15 nm. PS/PEO blend films show interconnected wormlike structure with a characteristic length of about 1 μxm, where depressed part shows the crystal structure, larger lateral force, and softer. We have concluded that the lower part is made of PEO.

An efficient method was developed to stretch DNA molecules on an atomically flat surface for AFM imaging. This method involves anchoring DNA molecules from their 5' ends to amino silanized mica surfaces. N-Succinimidyl6-[3'-(2-pyridyldithio) propionamido]hexanoate (LC-SPDP), a heterobifunctional cross-linker with a flexible spacer arm was used for this purpose. The immobilization process was carried out by introducing a thiol group to the 5' end of DNA by PCR. Thiolated molecules were then reacted with the cross linker to conjugate with its 2-pyridyl disulphide group via sulfhydryl exchange. The resulting complex was deposited on amino silanized mica where NHS -ester moiety of the cross linker reacted with the primary amino group on the surface. Samples were washed by a current of water and dried by an air jet in one direction parallel to the surface. DNA molecules were shown to be fully stretched in one direction on imaging them by AFM.

We studied the ion catching behavior of nanoscale molecular domains of bipyridine thiol embedded in alkanethiol self-assembled monolayers (SAMs) on Au(111) by scanning tunneling microscopy (STM) to construct and demonstrate the possibility of a molecular sensor. We used a bromine-terminated bipyridine thiol molecule, in which a bipyridine unit is connected to a conjugated phenylene–ethynylene system, and then successfully observed the protonation response of the bipyridine molecule. When the Au substrate was immersed into dilute CF3SO3H solution, the apparent height of bipyridine spots became lower after this treatment. On the other hand, when the substrate was immersed into 0.1 mM Pd complex solution, the apparent height of bipyridine spots became higher than that in the initial state. These findings demonstrate the possibility of constructing cation sensor using several molecular domains, and the different ion catching behaviors of bipyridine molecules may lead to the development of highly selective molecular sensors.

We observed image changes induced by the polarity change of electric fields, by scanning tunneling microscopy (STM), for pre-assembled alkanethiol self-assembled monolayers (SAMs) embedded with small amounts of the bipyridine moiety. In the case of bipyridine dithiol molecules, STM experiments revealed that the apparent thickness of the molecular protrusions was larger under the positive bias. In this case, it was considered that the image change was caused by a conductance difference with different polarities of the tip bias. However, for the bromine-terminated bipyridine molecules, the thickness of the molecular protrusions was larger under negative bias, contrary to the case of dithiol type molecule. We considered that this image change was caused by an actual molecular conformational change because of the strong dipole moment of bromine-terminated bipyridine molecule.

By applying large forces to the surface during an atomic force microscopy scanning, crystallized polyethylene oxide (PEO) films were modified and showed a new structure in which there are the formation of a nanometer-scale bundle structure and an increase of elastic stiffness. The modified part was removed by dropping benzene onto a rotating surface through a peeling process for the case of thin modified layers, while for thick layers, the local properties were recovered by absorbing benzene into the modified parts. In the course of these measurements, the thickness of the modified layers was estimated.

Adsorption and thermal or photodecomposition of triethylgallium (TEG) and trimethylgallium (TMG) on Si(111)-7×7 were investigated using a home-built scanning tunneling microscope (STM), Auger electron spectroscopy (AES), and thermal desorption spectroscopy (TDS). Adsorption of TEG and TMG at room temperature gave bright protrusions of Ga(C2H5)x(a) and Ga(CH3)x(a) (x=2, 3) on atop sites of Si adatoms with a slight preference for center adatoms over comer ones. The Ga(C2H5)x(a) and Ga(CH3)x(a) species were decomposed by UV irradiation probably due to absorption of UV photons by these adsorbates. Thermal decomposition of TEG on the 7×7 surface led to severe carbon deposition, particularly at low initial coverage of TEG, in contrast to the result reported on Si(100)-2×1.

Modifications of the phase‐separated surface of polystyrene–polyethyleneoxide (PS‐PEO) blend films were carried out by using an atomic force microscope. On PEO, contrary to PS, a scanning of a tip with large forces of 50 nN resulted in a modification of surface and increased the elastic stiffness. The modification was seen as regular stripes perpendicular to the scanning direction, which may be caused by the rearrangement of the PEO folding structure as a result of a balance of various forces during scanning. This rearrangement may increase the density of the films and hence causes the increase of the elastic stiffness. On the stripes, molecular images were obtained with friction force microscope, reflecting the folding structure of PEO.

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.

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.