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Journal Articles

The Effects of alloying and segregation for the reactivity and diffusion of oxygen on Cu$$_{3}$$Au(111)

Oka, Kohei*; Tsuda, Yasutaka*; Makino, Takamasa*; Okada, Michio*; Hashinokuchi, Michihiro*; Yoshigoe, Akitaka; Teraoka, Yuden; Kasai, Hideaki*

Physical Chemistry Chemical Physics, 16(36), p.19702 - 19711, 2014/08

 Times Cited Count:11 Percentile:40.66(Chemistry, Physical)

Journal Articles

Initial stages of Cu$$_{3}$$Au(111) oxidation; Oxygen induced Cu segregation and the protective Au layer profile

Tsuda, Yasutaka*; Oka, Kohei*; Makino, Takamasa*; Okada, Michio*; Di$~n$o, W. A.*; Hashinokuchi, Michihiro*; Yoshigoe, Akitaka; Teraoka, Yuden; Kasai, Hideaki*

Physical Chemistry Chemical Physics, 16(8), p.3815 - 3822, 2014/02

 Times Cited Count:14 Percentile:49.2(Chemistry, Physical)

Journal Articles

Temperature dependence of Cu$$_{2}$$O formation on Cu$$_{3}$$Au(110) surface with energetic O$$_{2}$$ molecular beams

Hashinokuchi, Michihiro*; Yoshigoe, Akitaka; Teraoka, Yuden; Okada, Michio*

Applied Surface Science, 287, p.282 - 286, 2013/12

 Times Cited Count:6 Percentile:29.47(Chemistry, Physical)

Journal Articles

Oxidation of TiAl surface with hyperthermal oxygen molecular beams

Hashinokuchi, Michihiro*; Tode, Mayumi*; Yoshigoe, Akitaka; Teraoka, Yuden; Okada, Michio*

Applied Surface Science, 276, p.276 - 283, 2013/07

 Times Cited Count:4 Percentile:20.64(Chemistry, Physical)

Journal Articles

The Temperature dependence of Cu$$_{2}$$O formation on a Cu(110) surface with an energetic O$$_{2}$$ molecular beam

Hashinokuchi, Michihiro*; Yoshigoe, Akitaka; Teraoka, Yuden; Okada, Michio*

Journal of Physics; Condensed Matter, 24(39), p.395007_1 - 395007_8, 2012/10

 Times Cited Count:5 Percentile:24.08(Physics, Condensed Matter)

Journal Articles

The Study of oxidation on TiAl surface with photoemission spectroscopy in conjunction with synchrotron radiation

Hashinokuchi, Michihiro*; Sumimoto, Yuichi*; Tode, Mayumi; Harries, J.; Okada, Michio*; Teraoka, Yuden; Kasai, Toshio*

Denki Gakkai Rombunshi, C, 130(10), p.1723 - 1729, 2010/10

The oxidation processes on a TiAl surface induced by a hyperthermal O$$_{2}$$ molecular beam (HOMB) with a translational energy of 2.2 eV was studied by X-ray photoemission spectroscopy in conjunction with synchrotron radiation. At a surface temperature of 300 K, the simultaneous growth of Al and Ti oxides accompanied with the segregation of Al$$_{2}$$O$$_{3}$$ near the surface was observed. The efficiency of oxidation for the HOMB incidence was smaller than that for O$$_{2}$$ backfilling (25 meV). Furthermore, the chemical compositions of oxide species (Al$$_{2}$$O$$_{3}$$, Ti$$_{2}$$O$$_{3}$$, TiO$$_{2}$$) on the TiAl surface were independent of the translational energy of incident O$$_{2}$$ molecule. The present results suggest that the oxidation on TiAl surface proceeds via precursor molecular states.

Journal Articles

Stereodynamics in dissociative adsorption of NO on Si(111)

Hashinokuchi, Michihiro*; Okada, Michio*; Ito, Hironori*; Kasai, Toshio*; Moritani, Kosuke*; Teraoka, Yuden

Physical Review Letters, 100(25), p.256104_1 - 256104_4, 2008/06

 Times Cited Count:16 Percentile:65.86(Physics, Multidisciplinary)

We report results of studies on surface-temperature dependence of steric effects in dissociative adsorption processes of NO molecules on Si(111)-(7$$times$$7) surface by means of X-ray photoemission spectroscopy. Data presented here show that the reactive sticking probability for N-end collisions is larger than that in O-end collisions at an incident energy of 58 meV. Furthermore, this steric preference is quite sensitive to the surface temperature and the surface coverage. These facts reveal that transient surface trapping of NO molecules in a shallow precursor state plays a key role in the initial step of the NO decomposition on the Si(111)-(7$$times$$7) surface.

Journal Articles

New oriented-molecular-beam machine for surface stereochemistry with X-ray photoemission spectroscopy

Okada, Michio*; Hashinokuchi, Michihiro*; Moritani, Kosuke*; Kasai, Toshio*; Teraoka, Yuden

Japanese Journal of Applied Physics, 47(5), p.3686 - 3691, 2008/05

 Times Cited Count:5 Percentile:22.79(Physics, Applied)

An oriented-molecular-beam technique based on the Stark effect of a molecule in an inhomogeneous hexapole electrostatic field is a potential tool for stereochemical control of surface reactions. This technique allows us to select a specific rotational quantum state and also an orientation of a reagent molecule. We have developed a new UHV-compatible oriented-molecular-beam machine. This apparatus is equipped with components for X-ray photoemission spectroscopy (XPS) in order to detect surface-reaction products. In the dissociative adsorption of NO on an Si(111) surface, we found a steric effect in the reactivity by monitoring the products on the surface with the new machine. The N-end collision is more reactive than the O-end collision at an incident energy of 58 meV. To our knowledge, this is the first measurement of the steric effect appearing in the reaction products on the surface.

Journal Articles

Dissociative adsorption of nitric oxide on Si(111)-(7$$times$$7) surface

Hashinokuchi, Michihiro*; Ito, Hironori*; Teraoka, Yuden; Moritani, Kosuke*; Okada, Michio*; Kasai, Toshio*

Japanese Journal of Applied Physics, 47(3), p.1672 - 1676, 2008/03

 Times Cited Count:4 Percentile:18.82(Physics, Applied)

Dissociative adsorption of nitric oxide (NO) on Si(111)-7$$times$$7 surface between 330-600 K was investigated using X-ray photoelectron spectroscopy. The uptake curves of both N and O atoms as a function of NO dose revealed a prominent temperature dependence of dissociative adsorption of NO on an Si(111)-7$$times$$7 surface. The decrease in the rates of dissociative adsorption of NO with increasing surface temperature suggested existence of a precursor state. Additionally, the N/O ratio on the surface changed from 1.0 at 330 K to 1.2 at 600 K. This increasing N/O ratio with increasing surface temperature suggests that an additional reaction path opens at higher surface temperature.

Journal Articles

Protective layer formation during oxidation of Cu$$_{3}$$Au(100) using hyperthermal O$$_{2}$$ molecular beam

Okada, Michio*; Hashinokuchi, Michihiro*; Fukuoka, Masayuki*; Kasai, Toshio*; Moritani, Kosuke*; Teraoka, Yuden

Applied Physics Letters, 89(20), p.201912_1 - 201912_3, 2006/11

 Times Cited Count:25 Percentile:64.97(Physics, Applied)

Oxidation of Cu$$_{3}$$Au(100) using a hyperthermal O$$_{2}$$ molecular beam (HOMB) was investigated by X-ray photoemission spectroscopy in conjunction with a synchrotron light source. From the incident energy dependence of the O-uptake curve, it was determined that the dissociative adsorption of O$$_{2}$$ implies a higher activation barrier and therefore less reactivity due to the Au alloying. The dissociative adsorption progresses with the Cu segregation on the surface. No prominent growth of Cu$$_{2}$$O even for 2 eV HOMB suggests that the Au-alloying of Cu can serve as a protective layer against further oxidation into the bulk.

JAEA Reports

Rotational states of CH$$_{3}$$CN selected using hexapole electric field (Cooperative research)

Hashinokuchi, Michihiro*; Okada, Michio*; Kasai, Toshio*; Moritani, Kosuke; Teraoka, Yuden

JAEA-Research 2005-002, 16 Pages, 2006/01

JAEA-Research-2005-002.pdf:0.91MB

The dynamical processes such as the energy transfer of a molecule to a surface, etc. play an important role in surface chemical reactions. An oriented-molecular-beam method can provide a great insight into these processes. We have developed a UHV-compatible oriented-molecular-beam machine. In the present study, we performed rotational-state selection of CH$$_{3}$$CN using hexapole electric field. We measured the focusing curve of CH$$_{3}$$CN, which was reproduced by the trajectory simulation including the second-order Stark effect in the inhomogeneous hexapole electric field. The expected orientation distributions suggest our ability to control the molecular orientation in surface reactions.

Journal Articles

Full characterization of an intense pulsed hyperthermal molecular beam

Watanabe, Daisuke*; Che, D.-C.*; Fukuyama, Tetsuya*; Hashinokuchi, Michihiro*; Teraoka, Yuden; Kasai, Toshio*

Review of Scientific Instruments, 76(5), p.055108_1 - 055108_5, 2005/05

 Times Cited Count:6 Percentile:33.47(Instruments & Instrumentation)

A molecular beam technique for generating an intense pulsed hyperthermal molecular beam (HTMB) was developed. The beam source consists of a pulse valve, a cooling-water bottle that protectes the pulse valve from heat transfer of a high temperature nozzle, and the nozzle with a heater. The pulsed HTMB of HCl was practically generated and characterized by means of (2+1) resonance-enhanced multiphoton ionization and ion time-of-flight techniques.

Oral presentation

Stereodynamics of surface chemical reactions on silicon

Okada, Michio*; Goto, Seishiro*; Hashinokuchi, Michihiro*; Moritani, Kosuke*; Teraoka, Yuden; Kasai, Toshio*

no journal, , 

We have been developing a new machine of ultra-high-vacuum compatible oriented-molecular beam apparatus. We report results of a study on the incident-energy and the surface-temperature dependence of the steric effects in the dissociative adsorption of CH$$_{3}$$Cl on an Si(100) surface. The initial sticking probability was measured by the King-Wells method. The data show that the initial sticking probability for the Cl-end collision is larger at an incident energy of 120 meV than that in the CH$$_{3}$$-end collision. Furthermore, this steric preference is quite sensitive to the kinetic energy and the rotational state and the surface temperature. This study shows that the non-equilibrium surface trapping plays a key role in the initial step of the decomposition. We also introduce the on-going experiments using a new apparatus for the reaction of oriented NO molecules with Si(111), we found that a N-end collision is more effective for the reaction than O-end collision.

Oral presentation

Molecular steric effects in dissociative adsorption of NO at Si(111)-7$$times$$7 surface

Hashinokuchi, Michihiro*; Moritani, Kosuke*; Okada, Michio*; Teraoka, Yuden; Kasai, Toshio*

no journal, , 

The dynamical processes such as energy transfer of molecules to surface, etc. play an important role in surface chemical reactions. Therefore, it is expected that molecular orientation affects the reaction rate and product compositions. In this study, we investigated the reaction dynamics in the NO/Si(111)-7$$times$$7 system using oriented molecular beam and XPS. Uptake curves of O1s and N1s for incidence of the oriented NO molecular beam were measured at surface temperature of 400 K. These results indicate that this reaction is the dissociative adsorption which is non-selective for N and O atom adsorption at 400 K. In addition, we found that N-end collision was more effective for the reaction than O-end collision.

Oral presentation

Dynamic steric effect in silicon chemistry

Hashinokuchi, Michihiro*; Okada, Michio*; Moritani, Kosuke*; Teraoka, Yuden; Kasai, Toshio*

no journal, , 

The orientation of an incident molecule is expected to play an important role in surface chemical reactions. In order to elucidate molecular orientation (Steric) effects, we have developed a ultra-high-vacuum compatible oriented-molecular beam line and applied it to investigation of reactions on Si surface. Steric effect of CH$$_{3}$$Cl/Si(001)-2$$times$$1 disociative adsorption was studied using the King-Wells method. It was found that the non-equilibrium surface trapping is a key of CH$$_{3}$$Cl dissociative adsorption on the Si(001) surface. We present a new approach using X-ray photoelectron spectroscopy. We applied this to the NO/Si(111)-7$$times$$7 system. It was found that the dissociative adsorption occurs via a precursor in the incident energy region from 25 to 78 meV. Reaction probability from N-end collision is higher than that of O-end collision. This result indicates that the kinetic energy of incident NO molecules was easy to loss in the N-end collision than O-end collision.

Oral presentation

Stereodynamics in the dissociative adsorption of NO on Si(111)

Hashinokuchi, Michihiro*; Okada, Michio*; Moritani, Kosuke*; Teraoka, Yuden; Kasai, Toshio*

no journal, , 

no abstracts in English

Oral presentation

Stereodynamics of surface chemical reactions on silicon

Okada, Michio*; Hashinokuchi, Michihiro*; Fukuyama, Tetsuya*; Teraoka, Yuden; Kasai, Toshio*

no journal, , 

Oriented supersonic molecular beams of NO and CH$$_{3}$$Cl molecules, which have a parmanent dipole molent, are generated by non-uniform electric fields. The oriented NO and CH$$_{3}$$Cl beams dissociate and adsorbed at Si(111) and Si(001) surfaces, respectively. Molecular orientation effects for the surface reactions were studied. Sticking probabilities were evaluated in the reactions of oriented CH$$_{3}$$Cl molecules with the Si(001) surface by the King and Wells method. High reactivity was obtained in the Cl-end collisions. And, elements on the Si(111) surface were analysed by X-ray photoemission spectroscopy in the NO reactions at the Si(111) surface. High reactivity was clarified in the N-end collisions.

Oral presentation

Stereodynamics of NO dissociative adsorption on Si(111)-(7$$times$$7) surface

Hashinokuchi, Michihiro*; Ito, Hironori*; Teraoka, Yuden; Moritani, Kosuke*; Okada, Michio*; Kasai, Toshio*

no journal, , 

We have studied molecular-orientation effects for the dissociative adsorption of NO on Si(111)-7$$times$$7 surface using an oriented-molecular-beam apparatus designed efficient for X-ray photoelectron spectroscopy. The state-selected NO molecular beam with translational energy of 58 meV impinges on the Si surface of 400 K and adsorbed sites of oxygen and nitrogen on the surface have been analyzed by XPS as O1s and N1s photoelectron peaks. The O1s peak revealed that the yield of dissociatively-adsorbed O atoms for the N-end collision was larger than that for the O-end collision, and that for randomly-oriented NO gave the middle value of the two. The same steric preference was observed for the N1s peak. We would thus conclude that the N-end collision is more reactive than the O-end one.

Oral presentation

Stereodynamics of chemical reactions in heterogeneous systems; Dissociative adsorption of NO on Si(111)

Hashinokuchi, Michihiro*; Okada, Michio*; Ito, Hironori*; Kasai, Toshio*; Moritani, Kosuke*; Teraoka, Yuden

no journal, , 

We present the steric effect recently observed in the dissociative adsorption of NO on Si(111)-7$$times$$7 surface by using an oriented-molecular-beam apparatus especially designed for X-ray photoelectron spectroscopy. The (1/2,1/2,1/2) state-selected NO molecular beam with the kinetic energy of 58 meV was incident to Si(111) surface and adsorbed species were analyzed by XPS. We find that the reaction is more favorable for the N-end than that for the O-end. The steric preference becomes very small at 600K. This result shows that transient trapping into a shallow precursor state plays the key role in the stereodynamics of this surface reaction.

Oral presentation

Chemical reactions dynamics; From atomic level to global view

Kasai, Toshio*; Hashinokuchi, Michihiro*; Okada, Michio*; Ito, Hironori*; Moritani, Kosuke*; Teraoka, Yuden

no journal, , 

It is very important to study on steric effects or orientational effects of inpinging molecules to understand chemical reactions with an atomic and molecular level. Recently, orientational effects of NO molecules for dissociative adsorption at Si(111)-7$$times$$7 surface has been observed by a surface analytical method using X-ray photoemission spectroscopy. Chemical reactivity of N-end collisions was larger than that of O-end collisions. It depended on surface temperature. It was concluded that NO molecules were trapped tentatively on the Si(111) surface.

34 (Records 1-20 displayed on this page)