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Journal Articles

Ortho-para conversion of molecularly chemisorbed H$$_{2}$$ on Pd(210)

Ueta, Hirokazu; Fukutani, Katsuyuki

Vacuum and Surface Science, 64(9), p.430 - 434, 2021/09

Journal Articles

Direct measurement of fast ortho-para conversion of molecularly chemisorbed H$$_{2}$$ on Pd(210)

Ueta, Hirokazu; Sasakawa, Yuya*; Ivanov, D.*; Ono, Satoshi*; Ogura, Shohei*; Fukutani, Katsuyuki

Physical Review B, 102(12), p.121407_1 - 121407_5, 2020/09

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

Ortho-to-para conversion of molecularly chemisorbed H$$_{2}$$ on a Pd(210) surface at a surface temperature of 50 K is reported. A combination of a pulsed molecular beam, photo-stimulated desorption and resonance-enhanced multiphoton ionization techniques was used for probing the change in the rotational states of molecularly chemisorbed H$$_{2}$$ on the surface. Our result shows that fast ortho-para conversion of chemisorbed H$$_{2}$$ occurs. The conversion time was experimentally determined to be about 2 s, which is in good agreement with a previous theoretical calculation. This agreement supports that the ortho-para conversion mechanism of the molecularly chemisorbed H$$_{2}$$ on Pd(210) is the two-step process based on the hyperfine-Coulomb excitation.

Journal Articles

Bias temperature instability characterization of advanced gate stacks

Fujieda, Shinji*; Terai, Masayuki*; Saito, Motofumi*; Toda, Akio*; Miura, Yoshinao*; Liu, Z.*; Teraoka, Yuden; Yoshigoe, Akitaka; Wilde, M.*; Fukutani, Katsuyuki*

ECS Transactions, 6(3), p.185 - 202, 2007/00

In order to find how bias temperature instability occurs in advanced gate stacks, we will review experimental results of our investigation on SiO$$_{2}$$, plasma-nitrided SiON, HfSiON and HfSiON with Ni-silicide electrodes. It thus seems that we need to clarify and control the chemical and physical influences on the insulator bulk and the insulator/Si interface caused by newly incorporated materials and process technologies, in order to ensure the reliability of bias temperature instability for advanced gate stacks.

Oral presentation

Growth mechanism of the ultra-thin oxide films on metal substrates

Wilde, M.*; Fukutani, Katsuyuki*; Moritani, Kosuke; Yoshigoe, Akitaka; Teraoka, Yuden

no journal, , 

Our previous real-time synchrotron X-ray photoelectron spectroscopy (XPS) investigations of the growth kinetics of ultra-thin Al$$_{2}$$O$$_{3}$$ films on NiAl(100) in O$$_{2}$$ have revealed a strong acceleration of the oxidation reaction by water. To clarify the oxidation mechanism, the present study examines whether the growth rate acceleration by H$$_{2}$$O correlates with an increased oxide thickness, as would be expected within the Cabrera-Mott model at large surface hydroxyl (OH) coverages. We thus evaluate the saturation thickness of the Al$$_{2}$$O$$_{3}$$ films from the take-off angle dependence of Al2p XPS emission signals from the oxide overlayer (Al$$^{3+}$$) and the metallic NiAl substrate (Al$$^{0}$$). The results confirm our expectation that at temperatures where OH is stable on Al$$_{2}$$O$$_{3}$$, H$$_{2}$$O oxidation should yield slightly thicker Al$$_{2}$$O$$_{3}$$ films than those grown in O$$_{2}$$. This confirms our hypothesis that the rate acceleration by H$$_{2}$$O below 500K is due to its ability to provide a higher stationary oxidant (OH) coverage than O$$_{2}$$. Consistent with the thermal stability of surface OH groups, the H$$_{2}$$O-related effects decrease at higher oxidation temperatures.

Oral presentation

Atomic configuration of silicene on an Al(111) substrate

Fukaya, Yuki; Matsuda, Iwao*; Fukutani, Katsuyuki

no journal, , 

no abstracts in English

Oral presentation

Structures of silicene and germanene on an Al(111) substrate

Fukaya, Yuki; Matsuda, Iwao*; Fukutani, Katsuyuki

no journal, , 

no abstracts in English

Oral presentation

Atomic configuration of hydrogen-terminated silicene on a Ag(111) substrate

Fukaya, Yuki; Feng, B.*; Fukutani, Katsuyuki; Matsuda, Iwao*

no journal, , 

no abstracts in English

Oral presentation

Rotational state distribution of molecularly chemisorbed H$$_{2}$$ on Pd(210)

Ueta, Hirokazu; Sasakawa, Yuya*; Ivanov, D.*; Ono, Satoshi*; Fukutani, Katsuyuki

no journal, , 

Oral presentation

Rotational-state distribution and ortho-para conversion of molecularly chemisorbed H$$_{2}$$ on Pd(210)

Ueta, Hirokazu; Sasakawa, Yuya*; Ivanov, D.*; Ono, Satoshi*; Ogura, Shohei*; Fukutani, Katsuyuki

no journal, , 

Oral presentation

Rotational-state distribution and ortho-para conversion of molecularly chemisorbed H$$_{2}$$ on Pd(210)

Ueta, Hirokazu; Sasakawa, Yuya*; Ivanov, D.*; Ono, Satoshi*; Fukutani, Katsuyuki

no journal, , 

While hydrogen typically chemisorbs dissociatively on a flat metal surface, it is known that hydrogen can molecularly chemisorb on stepped surfaces, such as Pd(210). In this study, using a combination of a pulsed molecular beam, photo-stimulated desorption and resonance-enhanced multiphoton ionization techniques, the rotational states of molecularly chemisorbed H$$_{2}$$ are probed. We will present the rotational state distribution of photo-desorbed H$$_{2}$$, and the o-p conversion process of molecularly chemisorbed H$$_{2}$$ will be discussed.

Oral presentation

A Study of ortho-para conversion of molecularly chemisorbed H$$_{2}$$ on Pd(210)

Ueta, Hirokazu; Sasakawa, Yuya*; Ivanov, D.*; Ono, Satoshi*; Ogura, Shohei*; Fukutani, Katsuyuki

no journal, , 

Surface defects such as step and kink affect surfaced reaction. While hydrogen typically chemisorbs dissociatively on a flat metal surface, it is known that hydrogen can molecularly chemisorb on stepped surfaces, such as Pd(210). Recently, we developed a technique to probe ortho-para conversion of adsorbed hydrogen which consists of a combination of a pulsed molecular beam, photo-stimulated desorption and resonance-enhanced multiphoton ionization techniques. We report a result of orho-para conversion time of molecularly chemisorbed H$$_{2}$$ on Pd(210).

Oral presentation

Measurement of ortho-para conversion time of molecularly chemisorbed H$$_{2}$$ on Pd(210)

Ueta, Hirokazu; Sasakawa, Yuya*; Ivanov, D.*; Ono, Satoshi*; Ogura, Shohei*; Fukutani, Katsuyuki

no journal, , 

no abstracts in English

Oral presentation

H$$_{2}$$ ortho-para conversion on a stepped Pd surface

Ueta, Hirokazu; Sasakawa, Yuya*; Ivanov, D.*; Ono, Satoshi*; Ogura, Shohei*; Fukutani, Katsuyuki

no journal, , 

We present a direct measurement of fast Ortho-Para conversion of molecularly chemisorbed H$$_{2}$$ on Pd(210) at a surface temperature of 50 K. The determined conversion time was about 2 sec, which is in reasonably agreement with a previous theoretical calculation. This agreement supports that ortho-para conversion mechanism of the molecularly chemisorbed H$$_{2}$$ on Pd(210) is the two-step process based on the hyperfine-Coulomb excitation.

Oral presentation

Hydrogen isotope separation used graphene-palladium electrode

Yasuda, Satoshi; Matsushima, Hisayoshi*; Asaoka, Hidehito; Fukutani, Katsuyuki

no journal, , 

We evaluated H/D separation factor of graphene-palladium electrode in hydrogen pumping cell. We revealed that in case of palladium electrode, the separation factor hardly increases while the factor significantly increased for graphene-palladium electrode.

Oral presentation

Hydrogen isotope gas separation used graphene-metal electrode in hydrogen pumping method

Yasuda, Satoshi; Matsushima, Hisayoshi*; Asaoka, Hidehito; Fukutani, Katsuyuki*

no journal, , 

no abstracts in English

Oral presentation

A Role of rotational energy transfer in H$$_{2}$$ ortho-para conversion

Ueta, Hirokazu; Fukutani, Katsuyuki

no journal, , 

Oral presentation

Development of low energy H$$^{+}$$ ion gun toward evaluation of H$$^{+}$$ permeability of graphene

Terasawa, Tomoo; Fukutani, Katsuyuki; Yasuda, Satoshi; Asaoka, Hidehito

no journal, , 

Low energy ion gun was developed toward the evaluation of the H$$^{+}$$ permeability of graphene. The ion beam with the kinetic energy of 20 eV showed the energy resolution of 0.5 eV after passing through the electrostatic hemispherical monochromater. The separation of H$$^{+}$$ and H$$_{2}$$$$^{+}$$ ions was also achieved by the Wien-type filter. The development of the low energy ion gun is expected to reveal the mechanism of the H$$^{+}$$ permeation of graphene.

Oral presentation

Development of low energy H$$^{+}$$ gun for evaluation of H$$^{+}$$ permeability of graphene

Terasawa, Tomoo; Fukutani, Katsuyuki; Yasuda, Satoshi; Asaoka, Hidehito

no journal, , 

18 (Records 1-18 displayed on this page)
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