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Journal Articles

Fast ortho-to-para conversion of molecular hydrogen in chemisorption and matrix-isolation systems

Ueta, Hirokazu; Fukutani, Katsuyuki*; Yamakawa, Koichiro

Frontiers in Chemistry (Internet), 11, p.1258035_1 - 1258035_7, 2023/08

https://doi.org/10.3389/fchem.2023.1258035
 Times Cited Count：0 Percentile：0.00(Chemistry, Multidisciplinary)

Molecular hydrogen has two nuclear-spin modifications called ${it ortho}$ and ${it para}$. Because of the symmetry restriction with respect to permutation of the two protons, the ${it ortho}$ and ${it para}$ isomers take only odd and even values of the rotational quantum number, respectively. The ${it ortho}$-to-${it para}$ conversion is promoted in condensed systems, to which the excess rotational energy and spin angular momentum are transferred. We review recent studies on fast ${it ortho}$-to-${it para}$ conversion of hydrogen in molecular chemisorption and matrix isolation systems, discussing the conversion mechanism as well as rotational-relaxation pathways.

Journal Articles

Rotational-energy transfer in H$$_{2}$$ ortho-para conversion on a metal surface; Interplay between electron and phonon systems

Ueta, Hirokazu; Fukutani, Katsuyuki

Journal of Physical Chemistry Letters (Internet), 14(34), p.7591 - 7596, 2023/08

https://doi.org/10.1021/acs.jpclett.3c01209
 Times Cited Count：1 Percentile：12.81(Chemistry, Physical)

Journal Articles

Probing copper and copper-gold alloy surfaces with space-quantized oxygen molecular beam

Tsuda, Yasutaka; Gueriba, J. S.*; Ueta, Hirokazu*; Di$~n$o, W. A.*; Kurahashi, Mitsunori*; Okada, Michio*

JACS Au (Internet), 2(8), p.1839 - 1847, 2022/08

https://doi.org/10.1021/jacsau.2c00156

Journal Articles

Focusing and spin polarization of atomic hydrogen beam

Nagaya, Yuki*; Nakatsu, Hiroki*; Ogura, Shohei*; Shimazaki, Kota*; Ueta, Hirokazu; Takeyasu, Kotaro*; Fukutani, Katsuyuki

Journal of Chemical Physics, 155(19), p.194201_1 - 194201_6, 2021/11

https://doi.org/10.1063/5.0068251
 Times Cited Count：1 Percentile：4.36(Chemistry, Physical)

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

https://doi.org/10.1380/vss.64.430

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

https://doi.org/10.1103/PhysRevB.102.121407
 Times Cited Count：3 Percentile：15.07(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

Development of a cryogenic ion mobility spectrometer for an isomer-selected photoexcitation and reaction studies

Shiina, Yoko*; Takaya, Kazunari*; Ueta, Hirokazu; Hirayama, Takato*; Nakano, Yuji*

Journal of Physics; Conference Series, 1412, P. 122021_1, 2020/06

https://doi.org/10.1088/1742-6596/1412/12/122021
 Times Cited Count：0 Percentile：0.00(Optics)

Oral presentation

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

Ueta, Hirokazu; Fukutani, Katsuyuki

no journal, , 

Oral presentation

H$$_{2}$$ nuclear conversion on surface

Ueta, Hirokazu; Fukutani, Katsuyuki

no journal, , 

no abstracts in English

Oral presentation

Rotational-energy transfer in ortho-para conversion of molecularly chemisorbed H$$_{2}$$ on Pd(210)

Ueta, Hirokazu; Fukutani, Katsuyuki

no journal, , 

Oral presentation

Rotational-energy transfer of hydrogen molecule on solid surface

Ueta, Hirokazu; Fukutani, Katsuyuki

no journal, , 

Oral presentation

Spin effect in surface reactions by atomic Hydrogen on a Ni surface

Ueta, Hirokazu; Ohashi, Yusei*; Ishizaki, Yuji*; Sun, Z.-D.*; Ozawa, Takahiro*; Fukutani, Katsuyuki

no journal, , 

no abstracts in English

Oral presentation

Probing copper and copper-gold surfaces with space-quantized oxygen molecular beams

Tsuda, Yasutaka; Gueriba, J. S.*; Ueta, Hirokazu; Di$~n$o, W. A.*; Kurahashi, Mitsunori*; Okada, Michio*

no journal, , 

Oral presentation

Spin effect in surface reactions by atomic hydrogen on Ni(111)

Ueta, Hirokazu; Ohashi, Yusei*; Sun, Z.-D.*; Ozawa, Takahiro*; Fukutani, Katsuyuki

no journal, , 

no abstracts in English

Oral presentation

Hydrogen interactions with metal surfaces; Nuclear spin conversion and adsorption

Ueta, Hirokazu

no journal, , 

no abstracts in English

Oral presentation

Rotational-energy transfer in H$$_{2}$$ ortho-para conversion on Pd(210)

Ueta, Hirokazu; Fukutani, Katsuyuki

no journal, , 

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

Hydrogenation of segregated germanene on Ag(111)/Ge(111) by atomic hydrogen

Suzuki, Seiya; Ozawa, Takahiro*; Ueta, Hirokazu; 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.

24 (Records 1-20 displayed on this page)