宮前 孝行

A series of amphiphic block copolymers containing poly[oligo(ethylene glycol) methacrylate] segments and the corresponding poly[methyl ethers of oligo(ethylene glycol) methacrylate] block copolymer surfaces are investigated by using sum-frequency generation (SFG) vibrational spectroscopy. The terminal moiety on the oligo(ethylene glycol) side chain played an important role in determining the surface structure of the block copolymer films. Due to the amphiphilic character of the methoxy oligo(ethylene glycol) side chain, the PME3MA block exposes the terminal methyl group to the surface and reduces the surface tension in air or vacuum, and it is possible that configurational entropy may also favor the presence of side chains at the surface. The molecular orientation of the block copolymer at the surface is modified due to the multilayered structures of the block copolymers. © 2006 The Surface Science Society of Japan.

A block copolymer of deuterated polystyrene (dPS) and 2-[2-(2-methoxyethoxy)ethoxyl ethyl methaerylate (PME3MA) spontaneously exposes the PME3MA, block, which is soluble in water, to the surface in a vacuum. dPS-PME3MA mixed with polystyrene (PS) segregates to the PS surface and changes the hydrophobic PS surface into hydrophilic surface. Neutron reflectivity, X-ray photoelectron spectroscopy, and dynamic secondary ion mass spectrometry probe the surface segregation of dPS-PME3MA to the surface of PS due to its PME3MA block. Sum-frequency generation vibrational spectroscopy detects exclusively the triethylene oxide (3EO) side chains of PME3MA regardless of a small fraction of dPS-PME3MA in the mixture, suggesting the conformation of the side chains influencing the segregation behavior. Because of the amphiphilic character of the methoxy-terminated 3EO side chains, the PME3MA block exposes the terminal methyl groups of the side chains to the surface to reduce the free energy of the system. However, such a hydrophobic methyl surface layer barely covers the EO part of the side chains; the surface quickly reconstructs and becomes hydrophilic upon contact with water. This is a technologically important demonstration of converting a hydrophobic polymer surface to a hydrophilic surface just by adding a small amount of block copolymer.

The surface molecular conformation of poly(ethylene terephthalate) (PET) and the interface between alumina and PET has been investigated by sum-frequency generation (SFG). An increase of the SFG peak intensity is observed after plasma treatment. Density functional theory confirms that the vibrational intensities from the PET surface are related to the surface molecular conformation. By depositing AIO(x), an increase of the SFG intensities and the appearance of a new peak at 1685 cm(-1) are observed, indicating the formation of a C=O center dot center dot center dot Al bond at the interface. (c) 2005 Elsevier B.V. All rights reserved.

The surface molecular conformation of poly(ethylene terephthalate) (PET) and the interface between alumina and PET has been investigated by sum-frequency generation (SFG). A considerable improvement in adhesion strength between AlO<Sub>x</Sub> and PET was achieved by short time Ar plasma modification. The increase in adhesion strength shows good correlation with the increase in SFG peak strength. By depositing AlO<Sub>x</Sub>, increase of SFG intensities and appearance of a new peak at 1,685 cm<Sup>-1</Sup> are observed, indicating the formation of a C=O···Al bond at the interface. Adhesion improvement by the Ar plasma treatment is not due to the increase in the C=O···Al chemical species at the interface, but due to the increase in the surface energy followed by the increase in the area of the homogeneous amorphous region of the PET and the creation of the surface hydroxyl groups induced by the plasma pretreatment.

Adsorption states of dioetyl dichalcogenides (dioctyl disulfide, dioctyl diselenide, and dioctyl ditelluride) arranged on Au(111) have been studied by X-ray photoelectron spectroscopy (XPS), infrared-visible sum-frequency generation (SFG), and ultraviolet photoelectron spectroscopy (UPS). XPS measurements suggest that dioctyl dichalcogenides dissociatively adsorbed on Au(111) surfaces to form the corresponding monolayers having chalcogen-gold covalent bonds. The elemental compositions of octanechalcogenolates on Au(111) indicate that the saturation coverages of the octyl heavy chalcogenolate (OcSe, OcTe) monolayers are lower than that of the octanethiolate (OcS) self-assembled monolayers (SAMs). The SFG observations of the CH2 vibrational bands for the heavy chalcogenolate monolayers strongly suggest that a discernible amount of gauche conformation exists in the monolayers, while OcS SAMs adopt highly ordered all-trans conformation. The intensity ratio of the symmetric and asymmetric CH3 stretching vibration modes measured by SFG shows that the average tilt angle of the methyl group of the OcSe monolayers is greater than that of the OcS SAMs. The larger tilt angle of the methyl group and the existence of a discernible amount of gauche conformation in the OcSe monolayers are due to the lower surface coverage of the OcSe monolayers compared with the OcS SAMs. The smaller polarization dependence in the angle-resolved UPS (ARUPS) spectra of the OcSe monolayers than that of the OcS SAMs is caused by the more disordered structures of the alkyl chain in the former. XPS, SFG, and ARUPS measurements indicate a similar tendency for the OcTe monolayers. The density of states (DOS) observed by UPS at around 1.3 eV for OcS adsorbed on Au(111) is considered to be the antibonding state of the Au-sulfur bond. Similar DOS is also observed by UPS at around 1.0 eV for the OcSe monolayers and at approximately 1.6 eV for the OcTe monolayers on Au(111).

Organic ditellurides (R2Te2 where R = n-butyl (C-4), n-octyl (C-8), and n-cetyl (C-16)) were synthesized, and their adsorption states after oxidation on Au(111) surfaces were studied by X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), theoretical analyses, near-edge X-ray absorption fine structure (NEXAFS) measurements, contact angle measurements, and atomic force microscopy (AFM). The obtained results show that dialkyl ditellurides form autooxidized monolayers (AMs) on the surfaces under ambient conditions and that the oxidation process is accelerated by ambient light. XPS, UPS, and theoretical analyses suggest that the autooxidized ditelluride species consist of polymers or oligomers with Te-O-Te-O network structures stabilized by oxygen bridges between tellurium molecules following the cleavage of tellurium-gold bonds. NEXAFS and contact angle measurements indicate that the average tilt angles of the alkyl chains from the surface normal are smaller for the AMs of dialkyl ditellurides having longer alkyl chains. AFM measurements show defects and roughness features around a few angstroms in height on the surfaces of the dialkyl ditelluride AMs.

The interface between AlOx and poly(ethylene terephthalate) has been investigated by sum-frequency generation (SFG). A considerable improvement in adhesion strength was achieved by short time Ar plasma modification. The increase of the adhesion strength shows good correlation with the increase of the SFG peak strength. By depositing AlOx, the increase of SFG intensities and appearance of a new peak are observed, indicating the formation of a C=O...Al bond at the interface. Surface-modification and interfacial adhesion property are discussed. (C) 2004 American Institute of Physics.

The surface morphology, molecular structure, and the surface restructuring behavior after the deposition of a SiO2 layer on poly(methyl methacrylate) (PMMA) have been investigated by using atomic force microscopy (AFM) in contact mode and sum-frequency generation (SFG) vibrational spectroscopy. AFM images show that the surface of PMMA is quite flat and sporadically contains dendritic features, which are micro-crystalline structures of PMMA. From the SFG measurements, the ester methyl groups of PMMA are pointed away from the surface plane at least in the surface region. By depositing a SiO2 film, the SFG signal intensity is significantly reduced, indicating that the C=O and the ester methyl groups are aligned nearly parallel to the surface plane. (C) 2003 Elsevier Science B.V. All rights reserved.

Microcontact-printing (muCP) method was used to functionalize silicon surfaces with aminosilane forming a pattern. We utilized the surface reactivity on the muCP pattern for vapor deposition polymerization to form patterned polymer films. On the muCP patterned substrates, two sets of monomers were evaporated in vacuum, and the polymerization was controlled by the substrate temperature and the evaporation sequences. By alternative pulsed vapor deposition of two monomers (terephthaloylchloride and 4,4'-diaminodiphenyl-ether) using pulse valves, we produced polyamide films on the patterned substrate at elevated temperature. We found that the aminosilanized areas showed increased thickness and flatter surface structure. One set of monomers did not grow preferentially on the functionalized surface and the resulting films did not exhibit structural or thickness differences. Our results indicate that the reactivity and the retention time of the monomers on the surface caused the different film growth on the activated and inert surfaces. (C) 2002 Elsevier Science B.V. All rights reserved.

The surface modified poly(ethylene terephthalate) (PET) film by its exposure to O-ion beam or O-radical beam, and the buried interface between an oxide layer and PET have been investigated by using sum-frequency generation. The O-ion beam exposure induces the cleavage of main chains and converts the ester moiety to -COOH terminal species. In contrast, O-radical beam does not induce degradation of main chains but it reacts to the polymer chain to form a new carbonyl species. After deposition of the TiO2 layer by using O-radical beam assisted method, C = O and phenyl ring of PET are tilted from the surface plane, In contrast to the case of TiO2/PET, deposition of SiO2 film does not induce changes in the molecular conformation of PET. (C) 2002 Elsevier Science Ltd. All rights reserved.

A new method for preparing aromatic polyamide-polyimide random copolymer films has been developed. Oxydianiline, pyromellitic dianhydride, and terephthaloyl chloride were evaporated separately from thermostatically controlled pulse molecular evaporation sources, which were actuated by solenoid valves, producing a polyimide-polyamide film after curing treatment. By selecting the appropriate combination of monomers, other copolymer films could be obtained through the sequential vacuum deposition polymerization process.

The surface structures after the synchrotron radiation (SR) stimulated removal of native oxide on Si (111) exactly oriented and 4 degrees misoriented surfaces were investigated by scanning tunneling microscopy. The exactly oriented surface showed large regions of atomically flat Si (III)-7X7 structure, and was characterized by the formation of single bilayer steps nicely registered to the underlying crystal structure, clearly different from the disordered step edge obtained by the usual high temperature thermal cleaning. The 4 degrees misoriented sample showed nearly uniformly spaced step bunches and terraces terminated by 7X7 unit cells in both SR assisted and thermal cleanings. (C) 2001 Elsevier Science BY. All rights reserved.

The surface structures of polyamic acid and polyimide films made by vapor deposition polymerization (VDP) technique were investigated using infrared-visible sum-frequency generation (SFG). From the SFG spectra of VDP-made polyamic acid films, the polymer chains have a broad orientational distribution, and residual monomers are observed even for a sample that was kept in air for more than 3 months. The amidization reaction of surface residual monomers is quite slow at room temperature, and the reaction proceeds preferentially in the bulk film. In the early stage of curing, surface species become parallel to the surface plane. After the surface reorientation, the imidization reaction proceeds.

The surface molecular orientation of biaxially stretched poly(ethylene terephthalate) (PET) films and the effect of the oxygen-ion and oxygen-radical beam irradiation on it have been investigated by using infrared-visible sum-frequency generation (SFG). The SFG spectra of PET surface showed a pronounced peak at 1705 cm(-1) which is characteristic of the C=O stretching vibration in an ester function. The SFG spectra indicate that the polymer chains at the surface appear to be well aligned parallel to the surface plane. The oxygen-ion beam exposure induces degradation of the polymer chain and converts the ester moiety to -COOH terminal species. In contrast to the case of oxygen-ion beam, oxygen-radical beam mainly affects the phenyl ring of PET. (C) 2001 Elsevier Science B.V. All rights reserved.

Ultraviolet photoelectron spectra were measured using synchrotron radiation for thin films of poly(1,10-phenanthroline-3,8-diyl) (PPhen) and its potassium-doped state. Upon potassium doping of PPhen, two new states, which could be assigned to bipolaron bands, appear in the originally empty energy gap. The electronic structure of the neutral and potassium-doped states was theoretically analyzed using single-scattering approximation combined with semiempirical molecular orbital calculations. © 1999 American Institute of Physics.

Ultraviolet photoelectron spectra were measured using synchrotron radiation for thin films of poly(1,10-phenanthroline-3,8-diyl) (PPhen) and its potassium-doped state. Upon potassium doping of PPhen, two new states, which could be assigned to bipolaron bands, appear in the originally empty energy gap. The electronic structure of the neutral and potassium-doped states was theoretically analyzed using single-scattering approximation combined with semiempirical molecular orbital calculations. © 1999 American Institute of Physics.

Ultraviolet photoelectron spectra of the metallofullerene, Sc@C82 are measured. The relative intensities of the band in the spectra varies with the incident photon energy change, as observed in other fullerenes. A difference spectrum between Sc@C82 and C82 shows two-peak components just below the Fermi level. Their intensity ratio suggests transfer of two electrons from the Sc atom to the fullerene cage.

Ultraviolet photoelectron spectra of the metallofullerene, Sc@C82 are measured. The relative intensities of the band in the spectra varies with the incident photon energy change, as observed in other fullerenes. A difference spectrum between Sc@C82 and C82 shows two-peak components just below the Fermi level. Their intensity ratio suggests transfer of two electrons from the Sc atom to the fullerene cage.

Ultraviolet photoelectron spectra of higher fullerenes C100 and C110 have been measured with a synchrotron radiation light source. The photoelectron onset energy of pristine C110 is 0.75 eV below the Fermi level (EF), which is the smallest value among the pristine fullerenes reported so far. The spectra show intensity oscillation upon the incident photon energy change, as do those of other fullerenes. A spectral change upon potassium doping has been observed with hν=20 and 40 eV incident photon energies. The appearance of a state between the first band of higher fullerenes and the Fermi level is observed in the hν=20eV spectra upon potassium doping. The onset position of the new state moves toward the EF. In the case of the potassium doping of C110, the spectral onset begins just at the EF, which indicates its possibility of semimetallic nature. When C110 is heavily doped with potassium the lower binding energy bands above 5 eV become faint, and three structures simultaneously appear between 5 and 14 eV and become distinct. As these structures are considered to be of s-electron origin, heavy potassium doping may correspond to reconstruction of the fullerene cage or decomposition of the cage structure. © 1999 The American Physical Society.

Ultraviolet photoelectron spectra of higher fullerenes C100 and C110 have been measured with a synchrotron radiation light source. The photoelectron onset energy of pristine C110 is 0.75 eV below the Fermi level (EF), which is the smallest value among the pristine fullerenes reported so far. The spectra show intensity oscillation upon the incident photon energy change, as do those of other fullerenes. A spectral change upon potassium doping has been observed with hν=20 and 40 eV incident photon energies. The appearance of a state between the first band of higher fullerenes and the Fermi level is observed in the hν=20eV spectra upon potassium doping. The onset position of the new state moves toward the EF. In the case of the potassium doping of C110, the spectral onset begins just at the EF, which indicates its possibility of semimetallic nature. When C110 is heavily doped with potassium the lower binding energy bands above 5 eV become faint, and three structures simultaneously appear between 5 and 14 eV and become distinct. As these structures are considered to be of s-electron origin, heavy potassium doping may correspond to reconstruction of the fullerene cage or decomposition of the cage structure. © 1999 The American Physical Society.

The ultraviolet photoelectron spectra measurements for 1st and 2nd stage potassium-oxygen-graphite intercalation compounds (KO(x)-GICs) were carried out for the electronic structure around the Fermi level E(F). The dependence of the photoelectron spectra upon the incident photon energy suggests the presence of the oxygen electronic states around E(F). The temperature dependence of the thermoelectric power (TEP) of KO(x)-GICs reveals the positive TEP below around 150 K for 1st stage compound, which suggests the contribution of hole carriers to the transport properties m contrast to the expectation of negative TEP endorsed by the donor type character of KO(x)-GIG. These experimental findings prove the contribution of intercalate to the electronic structure and transport properties.

Ultraviolet photoelectron spectra of metallofullerenes, GdC82 and La2C80 were measured with synchrotron orbital radiation. The specimens were dried-up films prepared from their solution instead of the sublimed films commonly adopted for the measurement. GdC82 gave structure rich spectra reflecting its electronic structure. The band intensity of the GdC82 spectra depends on the incident photon energy, as observed in other fullerenes. The similarity of the GdC82 spectra to those of LaC82 indicates that their electronic structures are analogous. The spectrum of La2C80 does not show any characteristic structures that have been observed in those of other fullerenes, and it resembles that of amorphous carbon. The C ls core photoelectron spectra of these metallofullerenes obtained with the Mg Kα radiation are also presented. © 1997 Published by Elsevier Science B.V.

Ultraviolet photoelectron spectra of metallofullerenes, GdC82 and La2C80 were measured with synchrotron orbital radiation. The specimens were dried-up films prepared from their solution instead of the sublimed films commonly adopted for the measurement. GdC82 gave structure rich spectra reflecting its electronic structure. The band intensity of the GdC82 spectra depends on the incident photon energy, as observed in other fullerenes. The similarity of the GdC82 spectra to those of LaC82 indicates that their electronic structures are analogous. The spectrum of La2C80 does not show any characteristic structures that have been observed in those of other fullerenes, and it resembles that of amorphous carbon. The C ls core photoelectron spectra of these metallofullerenes obtained with the Mg Kα radiation are also presented. © 1997 Published by Elsevier Science B.V.

N. Ueno, A. Kitamura, K. K. Okudaira, T. Miyamae, <br /> S. Hasegawa, H. Ishii, H. Inokuchi, T. Fujikawa, <br /> T. Miyazaki, and K. Seki<br /> Angle-resolved ultraviolet photoelectron spectroscopy of <br /> thin films of <br /> bis(1,2,5-thiadiazolo)-p-quinobis(1,3-dithiole) <br /> on MoS&lt;sub&gt;2&lt;/sub&gt; surface.

In this paper we report on the angle-resolved ultraviolet photoelectron spectroscopy on ultrathin films of bis(1,2,5-thiadiazolo)-p-quinobis (1,3-dithiole) (BTQBT) deposited on a MoS2 surface with synchrotron radiation, and describe the quantitative analysis of the angular distribution of photoelectron from the highest occupied state. The observed angular distributions were better explained by those calculated with the single-scattering approximation combined with molecular orbital calculation considering intramolecularly scattered waves than the previously used independent-atomic-center approximation combined with molecular orbital calculation. Further, the low-energy-electron diffraction measurements were performed on the film. From the low-energy-electron diffraction, the two-dimensional lattice of the ultrathin films on the MoS2 was found to be MoS2(0001)-(√13 × √13, R = ± 13.9°)-BTQBT, and from the analysis of the photoelectron angular distributions, it was found that at the lattice points the molecules lie flat with azimuthal orientations of 19° and 47° with respect to each surface crystal axis of MoS2. On the basis of these results, the full structure of the thin film, the two-dimensional lattice, and full molecular orientations at the lattice points, is proposed. © 1997 American Institute of Physics.

We investigate the electronic structure of AuCl3 graphite intercalation compounds by means of discrete variational (DV)-Xα molecular orbital calculation and ultraviolet photoelectron spectra (UPS). DV-Xα calculation of the Au2Cl6 intercalate reveals the importance of relativistic effect due to the presence of heavy Au atoms. The terminal Cl 3p orbital contributes mainly to the lowest unoccupied molecular orbital (LUMO) of Au2Cl6 molecule in addition to the minor contribution of the Au 5d component. The calculation of (Au2Cl6)-0.5, which is considered to be intercalate species realized in graphitic galleries through charge transfer from graphite, suggests that the Au2Cl6 intercalate band is located at around the Fermi level EF as well as the graphitic π-band. As a consequence, the density of states at EF is 2-3 times larger than that expected only by the graphitic π-band, which is consistent with optical reflectance, magnetic susceptibility, and the electronic specific heat. The small hump around EF in the UPS of AuCl3-GIC is considered to be associated with the intercalate band. The overlap population analysis suggests the bonds between gold and chlorine atoms in Au2Cl6 become weaker when the 0.5 electron transfer from graphitic π-band to Au2Cl6 molecule. Therefore, the interatomic distances in the Au2Cl6 molecule are found to become elongated, consistent with the experimental results of the Raman spectra.

We investigate the electronic structure of AuCl3 graphite intercalation compounds by means of discrete variational (DV)-Xα molecular orbital calculation and ultraviolet photoelectron spectra (UPS). DV-Xα calculation of the Au2Cl6 intercalate reveals the importance of relativistic effect due to the presence of heavy Au atoms. The terminal Cl 3p orbital contributes mainly to the lowest unoccupied molecular orbital (LUMO) of Au2Cl6 molecule in addition to the minor contribution of the Au 5d component. The calculation of (Au2Cl6)-0.5, which is considered to be intercalate species realized in graphitic galleries through charge transfer from graphite, suggests that the Au2Cl6 intercalate band is located at around the Fermi level EF as well as the graphitic π-band. As a consequence, the density of states at EF is 2-3 times larger than that expected only by the graphitic π-band, which is consistent with optical reflectance, magnetic susceptibility, and the electronic specific heat. The small hump around EF in the UPS of AuCl3-GIC is considered to be associated with the intercalate band. The overlap population analysis suggests the bonds between gold and chlorine atoms in Au2Cl6 become weaker when the 0.5 electron transfer from graphitic π-band to Au2Cl6 molecule. Therefore, the interatomic distances in the Au2Cl6 molecule are found to become elongated, consistent with the experimental results of the Raman spectra.

Ultraviolet photoelectron spectra were measured using synchrotron radiation for two kinds of π-conjugated polymers, poly(pyridine-2,5-diyl) (PPy) and poly(2,2′-bipyridine-5,5′-diyl) (PBPy) which exhibit n-type electrically conducting properties. The two compounds show similar spectra and they were analyzed with MO calculations and the comparison with the data of related molecules. The ionization threshold energies of PPy and PBPy were found to be 6.3 and 6.35 eV, respectively. These values are higher than those of π-conjugated conducting polymers capable of p doping. Upon potassium doping of PBPy, two new states appeared in the originally empty energy gap and the intensity of the state at 0.65 eV from EF grows as the doping proceeds. This finding and the change of optical absorption spectra upon doping indicate that bipolaron bands are formed in K-doped PBPy. While K-doped PPy also shows similar gap states, it requires higher dopant concentration to create bipolaron bands than in the case of K-doped PBPy. The difference of the dependence on dopant concentration between K-doped PPy and K-doped PBPy is discussed based on the conformational difference between these polymers. © 1995 American Institute of Physics.

Ultraviolet photoelectron spectra were measured using synchrotron radiation for two kinds of π-conjugated polymers, poly(pyridine-2,5-diyl) (PPy) and poly(2,2′-bipyridine-5,5′-diyl) (PBPy) which exhibit n-type electrically conducting properties. The two compounds show similar spectra and they were analyzed with MO calculations and the comparison with the data of related molecules. The ionization threshold energies of PPy and PBPy were found to be 6.3 and 6.35 eV, respectively. These values are higher than those of π-conjugated conducting polymers capable of p doping. Upon potassium doping of PBPy, two new states appeared in the originally empty energy gap and the intensity of the state at 0.65 eV from EF grows as the doping proceeds. This finding and the change of optical absorption spectra upon doping indicate that bipolaron bands are formed in K-doped PBPy. While K-doped PPy also shows similar gap states, it requires higher dopant concentration to create bipolaron bands than in the case of K-doped PBPy. The difference of the dependence on dopant concentration between K-doped PPy and K-doped PBPy is discussed based on the conformational difference between these polymers. © 1995 American Institute of Physics.