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Journal Articles

Surface segregation effect for prevention of oxidation in Ni-X (X=Sn, Sb) alloy by in situ photoelectron spectroscopy

Doi, Takashi*; Yoshigoe, Akitaka

Surface and Interface Analysis, 52(12), p.1117 - 1121, 2020/12

 Times Cited Count:1 Percentile:3.25(Chemistry, Physical)

Ni-base alloys has been widely used for chemical plants because of their high strength and excellent oxidation resistance. In particular, the addition of Sn and Sb in Ni-base alloys significantly improves the metal dusting resistance. It is indicated that Sn and Sb are segregated on the alloy surface in the metal dusting environment; however, the details have not been clarified yet. The behavior of the Ni-Sn and Ni-Sb alloys under a high-temperature oxidation environment was investigated by in situ X-ray photoelectron spectroscopy. It was confirmed that Sn and Sb have been segregated at the surface of their alloys during oxidation in low oxygen potential environment. These results indicate that Sn and Sb segregation improves the metal dusting resistance.

Journal Articles

Auger electron spectroscopic analysis of corrosion products formed on A3003 aluminum alloy in model fresh water with different Zn$$^{2+}$$ concentration

Otani, Kyohei; Islam, M. S.*; Sakairi, Masatoshi*; Kaneko, Akira*

Surface and Interface Analysis, 51(12), p.1207 - 1213, 2019/12

 Times Cited Count:1 Percentile:2.39(Chemistry, Physical)

The corrosion morphology and composition of corrosion products of A3003 formed in model fresh water with different Zn$$^{2+}$$ concentrations were investigated by immersion tests combined with surface observations and analysis using an auger electron spectroscope (AES). The cross-sectional AES observations showed that the thickness of the corrosion product layer formed on A3003 decreases with increases in the Zn$$^{2+}$$ concentration of the model fresh water. A cross-sectional AES point analysis suggested that the corrosion products formed on the A3003 in the Zn$$^{2+}$$ containing model fresh water (Zn$$^{2+}$$ $$>$$ 0.1 mM) have a multi-layer structure, and that the inner of Zn-rich layer would have high corrosion protective properties.

Journal Articles

Non-destructive depth analysis of the surface oxide layer on Mg$$_{2}$$Si with XPS and XAS

Esaka, Fumitaka; Nojima, Takehiro; Udono, Haruhiko*; Magara, Masaaki; Yamamoto, Hiroyuki

Surface and Interface Analysis, 48(7), p.432 - 435, 2016/07

 Times Cited Count:15 Percentile:39.1(Chemistry, Physical)

XPS is widely used for non-destructive chemical state analysis of solid materials. In this method, depth profiling can be carried out by a combination with ion beam sputtering. However, the sputtering often causes segregation and preferential sputtering of atoms and gives inaccurate information. The use of energy-tunable X-rays from synchrotron radiation (SR) enables us to perform non-destructive depth profiling in XPS. Here, the analytical depth can be changed by changing excitation X-ray energy. In the present study, we examined methods to perform depth profiling with XPS by changing excitation energy and XAS by changing electron energy for detection. These methods were then applied to the analysis of native surface oxide layers on Mg$$_{2}$$Si crystals. In this XAS analysis, the peak at 1843.4 eV becomes dominant when the electron energy for detection increases, which implies that Si-O or Si-O-Mg structure is formed as the surface oxide layer on the Mg$$_{2}$$Si.

Journal Articles

Investigation of segregation during oxidation of Ni-Cu alloy by ${{it in situ}}$ photoelectron spectroscopy

Doi, Takashi*; Nishiyama, Yoshitaka*; Yoshigoe, Akitaka; Teraoka, Yuden

Surface and Interface Analysis, 48(7), p.685 - 688, 2016/07

 Times Cited Count:4 Percentile:9.94(Chemistry, Physical)

Ni-based alloys has been widely used for plant application because of their high strength and excellent oxidation resistance. In particular, the addition of Cu in Ni-based alloys significantly improves the metal dusting resistance. It is indicated that Cu is segregated on the alloy surface in the metal dusting environment; however, the details have not been clarified yet. The behavior of Ni-2Cu alloy under a high temperature oxidation environment was investigated using ${{it in situ}}$ X-ray photoelectron spectroscopy. It was confirmed that Cu have been segregated at the surface of Ni-2Cu alloy during oxidation. These results propose that the Cu segregation improves the metal dusting resistance.

Journal Articles

Self-accelerating oxidation on Si(111)7$$times$$7 surfaces studied by real-time photoelectron spectroscopy

Tang, J.*; Nishimoto, Kiwamu*; Ogawa, Shuichi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Watanabe, Daiki*; Teraoka, Yuden; Takakuwa, Yuji*

Surface and Interface Analysis, 46(12-13), p.1147 - 1150, 2014/12

 Times Cited Count:1 Percentile:1.75(Chemistry, Physical)

Journal Articles

Orientation of Si phthalocyanine investigated by X-ray absorption spectroscopy and molecular orbital calculation

Sekiguchi, Tetsuhiro; Baba, Yuji; Shimoyama, Iwao; Honda, Mitsunori; Hirao, Norie; Narita, Ayumi; Deng, J.*

Surface and Interface Analysis, 42(6-7), p.863 - 868, 2010/06

 Times Cited Count:1 Percentile:1.8(Chemistry, Physical)

Metal phthalocyanines (Pc) have attracted growing attention due to potential application as organic semiconductors or light emitters. Recently it has been pointed out that orientation of Pc molecules is one of key properties that improve the career mobility. We studied orientation property of Si-phthalocyanine thin films using synchrotron radiation. We report on following topics: (1) Orientation analysis using polarized X-rays, (2) Effect of metal substrates and annealing on orientation, (3) Analysis aided by molecular orbital method, and (4) New method to observe chemical-bond directions in nanometer scale using combined techniques of polarized X-ray absorption fine structure (XAFS) spectroscopy and photoelectron emission microscopy (PEEM).

Journal Articles

Femto- and attosecond electron dynamics in 5'-Guanosine monophosphate interface as probed by resonant Auger spectroscopy

Ikeura, Hiromi*; Sekiguchi, Tetsuhiro

Surface and Interface Analysis, 42(6-7), p.1085 - 1088, 2010/06


 Times Cited Count:5 Percentile:11.31(Chemistry, Physical)

To help in our understanding of the electron transport properties of deoxyribonucleic acid (DNA), it is useful to study the interfacial interaction between each nucleotide building block of DNA. Electron transfer properties between phosphate and groups in microcrystalline 5'-Guanosine monophosphate (GMP) were probed using energy-dependent resonant Auger spectroscopy. Results show that the phosphate group of GMP forms an extended state along the phosphate directions similar to the case of DNA phosphate backbones. Electron delocalization time of the phosphate groups in GMP is faster than those of DNA, as estimated using the core-hole clock method. This suggests that interface between GMP phosphate groups would have the lowest tunneling barrier among DNA related systems. Although the $$pi$$-$$pi$$ coupling of nucleobasis is only recognized as charge-transfer pathway in DNA and related systems, another conduction pathway through phosphate groups would be possible.

Journal Articles

High-energy total reflection X-ray photoelectron spectroscopy for polished iron surface

Nagoshi, Masayasu*; Kawano, Takashi*; Makiishi, Noriko*; Baba, Yuji; Kobayashi, Katsumi*

Surface and Interface Analysis, 40(3-4), p.738 - 740, 2008/04

 Times Cited Count:3 Percentile:7.13(Chemistry, Physical)

Grazing incidence X-ray photoelectron spectroscopy (XPS) has been applied to mirror-polished stainless steel sheets and Si-wafer using incident X-ray with high energy from synchrotron radiation. Monochromatized X-ray with the energy of 1.8 keV to 3.6 keV was irradiated to the sample surfaces with various incident angles. Total reflection condition with the high-energy incident X-ray provides us X-ray photoelectron spectra having remarkably low background intensity. The results will be compared with background calculations in previous researches and discussed in terms of the penetration depth of X-ray and inelastic mean free path of photoelectrons. We also discuss the depth information of the obtained spectra.

Journal Articles

Unoccupied electronic states in polythiophene as probed by XAS and RAS

Ikeura, Hiromi*; Sekiguchi, Tetsuhiro

Surface and Interface Analysis, 40(3-4), p.673 - 675, 2008/03


 Times Cited Count:14 Percentile:35.09(Chemistry, Physical)

Polythiophene is one of the typical conducting polymers. Unoccupied electronic states near the Fermi level of polythiophene polycrystalline powder were probed by S 1s X-ray absorption spectroscopy (XAS) and S$$KL_{2,3}$$, $$L_{2,3}$$ resonant Auger spectroscopy (RAS). Its overall XAS spectral shape is similar to those of 2,-2'-bithiophene and alpha-terthiophene polycrystalline powder. Any hybridization of the energy levels of thiophene unit was not observed in the $$pi^{*}$$-LUMO (the lowest unoccupied molecular orbital). It is found that the position of $$sigma^{*}$$(C-C) resonance shifts to lower energy as increasing thiophene repeating units. This finding reflects the different bond lengths of C-C. Although $$pi^{*}$$ and $$sigma^{*}$$(S-C) states in XAS are not resolved due to their overlap of electronic transitions, those were clearly separated by plotting spectator Auger yields as a function of excitation energy. If the Auger spectator shifts of the corresponding states are different each other, such unresolved states in XAS can be distinguished by RAS technique. RAS also indicates that the $$pi^{*}$$-LUMO of polythiophene has localized character. The present study demonstrated that excitation energy-dependent RAS can overcome the limitation of conventional XAS. The obtained results suggest that polythiophene is poorly conjugated, where the $$pi^{*}$$ delocalization is interrupted by the conformational disorder.

Journal Articles

Characterization of F$$^{+}$$-irradiated graphite surfaces using photon-stimulated desorption spectroscopy

Sekiguchi, Tetsuhiro; Baba, Yuji; Shimoyama, Iwao; Nath, K. G.

Surface and Interface Analysis, 38(4), p.352 - 356, 2006/04

 Times Cited Count:3 Percentile:7.3(Chemistry, Physical)

We investigated the orientation nature at the top-most layers of F$$^{+}$$-irradiated graphite using polarization dependent near-edge X-ray absorption fine structure (NEXAFS) spectroscopy which incorporates partial electron yield (PEY) detection and photon-stimulated ion desorption (PSID) techniques. The fluorine K-edge NEXAFS spectra conducted in PEY mode show no significant dependence on polarization angles. In contrast, NEXAFS spectra recorded in F$$^{+}$$ ion yield mode show enhanced yields at a feature of $$sim$$689.4 eV assigned as a $$sigma$$*(C-F) state relevant to =C-F sites, which depend on polarization angles. The C-F bonds prefer relatively tilting down the surface at the top-most layer, while the C-F bonds are randomly directed at deeper regions. We conclude that the difference in the orientation structures between the top surface and bulk is reflected in the NEXAFS recorded in the two different detection modes. It was also found that H$$^{+}$$- and F$$^{2+}$$- PSID NEXAFS spectra are helpful in understanding desorption mechanism, thus in analysing NEXAFS data.

Journal Articles

AFM observation of nanosized SiC dots prepared by ion beam deposition

Xu, Y.; Narumi, Kazumasa; Miyashita, Kiyoshi*; Naramoto, Hiroshi

Surface and Interface Analysis, 35(1), p.99 - 103, 2003/01

 Times Cited Count:9 Percentile:25.46(Chemistry, Physical)

no abstracts in English

Journal Articles

Formation of promising Co-C nanocompositions

Lavrentiev, V.; Abe, Hiroaki; Yamamoto, Shunya; Naramoto, Hiroshi; Narumi, Kazumasa

Surface and Interface Analysis, 35(1), p.36 - 39, 2003/01

 Times Cited Count:8 Percentile:22.95(Chemistry, Physical)

no abstracts in English

Journal Articles

${it In situ}$ analysis using synchrotron radiation photoemission spectroscopy for initial oxidation of oxygen preadsorbed Si(001) surfaces induced by supersonic O$$_{2}$$ molecular beams

Yoshigoe, Akitaka; Teraoka, Yuden

Surface and Interface Analysis, 34(1), p.432 - 436, 2002/08

 Times Cited Count:3 Percentile:8.75(Chemistry, Physical)

no abstracts in English

Journal Articles

Non-equilibrium intergranular segregation and embrittlement in neutron-irradiated ferritic alloys

Kameda, Jun*; Nishiyama, Yutaka; Bloomer, T. E.*

Surface and Interface Analysis, 31(7), p.522 - 531, 2001/07

 Times Cited Count:10 Percentile:29.18(Chemistry, Physical)

This study describes intergranular segregation and embrittlement in several model ferritic alloys doped with Mn, P, S and/or Cu subjected to neutron irradiation, irradiation-equivalent thermal ageing (ETA) and post-irradiation annealing (PIA). Neutron irradiation produced a larger amount of intergranular P segregation than S segregation. Intergranular C segregation remained small in all the as-irradiated alloys. A PIA study has shown that the P segregation in P-doped alloys subjected to lower temperature PIA proceeds via mobile P-interstitial complexes while the S segregation is controlled by vacancy-enhanced diffusion. The mechanisms of non-equilibrium intergranular segregation induced by neutron irradiation are discussed in light of coupled fluxes of point defects and impurities, and changes in the segregation capacity of grain boundaries. Small punch tests demonstrated how the impurity segregation or desegregation and hardening or softening induced by the irradiation, ETA and PIA influence intergranular embrittlement in the various ferritic alloys.

Journal Articles

Electronic structure of N$$_{2+}$$ and O$$_{2+}$$ ion-implanted Si(100)

Yamamoto, Hiroyuki; Baba, Yuji; Sasaki, Teikichi

Surface and Interface Analysis, 23, p.381 - 385, 1995/00

 Times Cited Count:17 Percentile:54.15(Chemistry, Physical)

no abstracts in English

Journal Articles

Photoelectron spectroscopic and surface resistance measurements of TiO$$_{2}$$ and V$$_{2}$$O$$_{5}$$ after rare-gas sputtering

Sasaki, Teikichi; Baba, Yuji; Yamamoto, Hiroyuki; Sasase, Masato*; *

Surface and Interface Analysis, 20, p.682 - 686, 1993/00

 Times Cited Count:4 Percentile:21.54(Chemistry, Physical)

no abstracts in English

Journal Articles

Application of X-ray-induced Auger electron spectroscopy to state analyses of hydrogen implanted in Y,Zr and Nb metals


Surface and Interface Analysis, 6(4), p.171 - 173, 1984/00

 Times Cited Count:35 Percentile:76.42(Chemistry, Physical)

no abstracts in English

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