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Masashi Arakawa Last modified date:2019.06.24

Assistant Professor / Physical Chemistry
Department of Chemistry
Faculty of Sciences


Graduate School
Undergraduate School


E-Mail
Homepage
http://www.scc.kyushu-u.ac.jp/quantum/index_j.php
Phone
092-802-4122
Fax
092-802-4122
Academic Degree
Ph.D.
Country of degree conferring institution (Overseas)
No
Field of Specialization
Physical Chemistry
ORCID(Open Researcher and Contributor ID)
0000-0002-5954-8893
Research
Research Interests
  • Physical chemistry of atomic and molecular clusters
    keyword : Physical chemistry, cluster, chemical reaction, water, ice
    2011.04~2020.03.
Academic Activities
Papers
1. M. Arakawa, K. Ando, S. Fujimoto, S. Mishra, G. Naresh Patwari, and A. Terasaki, The role of electronegativity on the extent of nitridation of group 5 metals as revealed by reactions of tantalum cluster cations with ammonia molecules, Physical Chemistry Chemical Physics, 10.1039/c8cp00424b, 20, 13794-13982, 2018.04, Reactions of the free tantalum cation, Ta+, and tantalum cluster cations, Tan+ (n = 2–10), with ammonia are presented. The reaction of the monomer cation, Ta+, with two molecules of NH3 leads to the formation of TaN2H2+ along with release of two H2 molecules. The dehydrogenation occurs until the formal oxidation number of the tantalum atom reaches +5. On the other hand, all the tantalum cluster cations, Tan+, react with two molecules of NH3 and form TanN2+ with the release of three H2 molecules. Further exposure to ammonia showed that TanNmH+ and TanNm+ are produced through successive reactions; a pure nitride and three H2 molecules are formed for every other NH3 molecule. The nitridation occurred until the formal oxidation number of the tantalum atoms reaches +5 as in the case of TaN2H2+ in contrast to other group 5 elements, i.e., vanadium and niobium, which have been reported to produce nitrides with lower oxidation states. The present results on small gas-phase metal- nitride clusters show correlation with their bulk properties: tantalum is known to form bulk nitrides in the oxidation states of either +5 (Ta3N5) or +3 (TaN), whereas vanadium and niobium form nitrides in the oxidation state of +3 (VN and NbN). Along with DFT calculations, these findings reveal that nitridation is driven by the electron-donating ability of group 5 elements, i.e., electronegativity of the metal plays a key role in determining the composition of the metal nitrides..
2. Masashi Arakawa, Tsubasa Omoda, Akira Terasaki, Adsorption and Subsequent Reaction of a Water Molecule on Silicate and Silica Cluster Anions, Journal of Physical Chemistry C, 10.1021/acs.jpcc.6b11689, 2017.01, We present reactions of size-selected free silicate, MglSiOm−, and silica, SinOm−, cluster anions with a H2O molecule focusing on H2O adsorption. It was found that H2O adsorption to MglSiOm− with l = 2 and 3 (m = 4−6) is always followed by molecular oxygen release, whereas reactivity of the clusters with l = 1 (m = 3−5) was found to be much lower. On the contrary, in the reaction of SinOm− (n = 3−8, 2n − 1 ≤ m ≤ 2n + 2), a H2O adduct is observed as a major reaction product. Larger and oxygen- rich clusters tend to exhibit higher reactivity; the rate constants of the adsorption reaction are 2 orders of magnitude larger than those of CO adsorption previously reported. DFT calculations revealed that H2O is dissociatively adsorbed on SinOm− to form two SiO3(OH) tetrahedra. The site selectivity of H2O adsorption is governed by the location of the singly occupied molecular orbital (SOMO) on SinOm−. The present findings give molecular-level insights into H2O adsorption on silica and silicate species in the interstellar environment..
3. Masashi Arakawa, Ryo Yamane, Akira Terasaki, Reaction sites of CO on size-selected silicon-oxide cluster anions: a model study of chemistry in the interstellar environment, Journal of Physical Chemistry A, 10.1021/acs.jpca.5b08900, 120, 139-144, 2016.01.
4. Masashi Arakawa, Kei Kohara, Akira Terasaki, Reaction of aluminum cluster cations with a mixture of O2 and H2O gases: Formation of hydrated-alumina clusters, Journal of Physical Chemistry C, 10.1021/jp511293g, 119, 10981-10986, 2015.04, We present reactions of size-selected free aluminum cluster
cations, AlN+ (N = 1−14), exposed to a mixture of water and oxygen gases.
It is featured that chemical species assignable to Al2O6H7+ and Al2O7H9+
were commonly produced as prominent reaction products from all of the
sizes, except N = 1. These product ions were found to be produced via the
formation of Al2O3+ in the initial stage of reactions with O2 and H2O,
which was followed by successive hydrogenation and hydration. This
reaction pathway was identified by examining reactivity of each
intermediate product step by step. Structures of the product ions were
analyzed by collision-induced dissociation experiments and DFT calculations; for+ example, coexistence of isomers, Al2O5H5(H2O)+ and
Al2O4H3(H2O)2 , with one and two intact H2O molecules, respectively, was suggested for Al2O6H7+. The chemical compositions of the ions +
produced in the present reactions are expressed nominally as Al2O3(H2O)nH , which is similar, except for the proton, to that of hydrated alumina, that is, forms of bulk aluminum abundant naturally. The present finding gives molecular-level insights into formation processes of aluminum minerals in a natural environment..
5. Masashi Arakawa, Kei Kohara, Tomonori Ito, Akira Terasaki, Size-dependent reactivity of aluminum cluster cations toward water molecules, European Physical Journal D, 2013.04.
6. Arakawa M., Kagi H., Fernandez-Baca J. A., Chakoumakos B. C. and Fukazawa H., The existence of memory effect on hydrogen ordering in ice: The effect makes ice attractive, Geophysical Research Letters, in press, 2011.08.
7. Arakawa M., Kagi H. and Fukazawa H., Annealing effects on hydrogen ordering in KOD-doped ice observed using neutron diffraction, Journal of Molecular Structure, doi:10.1016/j.molstruc.2010.02.016, 982, 111, 2010.03.
8. Arakawa M., Kagi H. and Fukazawa H., Laboratory measurements of infrared absorption spectra of hydrogen-ordered ice: a step to the exploration of ice XI in space, Astrophysical Journal Supplement Series, doi:10.1088/0067-0049/184/2/361, 184, 361-365, 2009.09.
9. Arakawa M., Yamamoto J. and Kagi H., Developing micro-Raman mass spectrometry for measuring carbon isotopic composition of carbon dioxide, Applied Spectroscopy, doi:10.1366/000370207781393244, 61, 701-705, 2007.07.
10. Arakawa M., Yamamoto J. and Kagi H., Micro-Raman thermometer for CO2 fluids: Temperature and density dependence on Raman spectra of CO2 fluids, Chemistry Letters, doi:10.1246/cl.2008.280, 37, 280-281, 2008.02.
Presentations
1. Masashi Arakawa, G. Naresh Patwari, Akira Terasaki, The origin of bulk-nitride composition of group 5 metals as revealed by nitridation of tantalum cluster cations by ammonia molecules, International Congress on Pure & Applied Chemistry Langkawi (ICPAC Langkawi 2018), 2018.10.
2. M. Arakawa, K. Ando, S. Fujimoto, S. Mishra, G. Naresh Patwari, and A. Terasaki, Successive nitridation of tantalum cluster cations by ammonia molecules: The origin of bulk-nitride composition of group 5 metals, 19th International Symposium on Small Particles and Inorganic Cluster (ISSPIC XIX), 2018.08, Tantalum nitride is an attractive material with a potential for various applications, e.g., copper diffusion barriers in microelectronics, an interlayer in magnetic random access memories, and photocatalysts for H2 evolution. Elucidation of nitridation mechanism of tantalum at the molecular level would supply a useful recipe for fabricating high-quality tantalum-nitride materials. In this context, gas-phase clusters provide an ideal approach to probe reactions step by step with precise control in the number of atoms and molecules involved in a reaction [1,2]. In the present study, nitridation of free tantalum cation, Ta+, and tantalum cluster cations, Tan+, by ammonia molecules is investigated [3], since it is known that nitridation does not proceed by nitrogen molecules [4].
In the experiment, Tan+ (n = 1–10) was generated by a magnetron-sputter cluster-ion source. They were mass-selected and guided into a reaction cell filled with NH3 molecules. The ions produced by the reaction were identified by a quadrupole mass analyzer.
The reaction of monomer cation, Ta+, with two molecules of NH3 leads to formation of TaN2H2+ along with release of two H2 molecules. The dehydrogenation occurs until the formal oxidation number of the tantalum atom reaches +5. On the other hand, all the tantalum cluster cations, Tan+, react with two molecules of NH3 and form TanN2+ with the release of three H2 molecules. Further exposure to ammonia showed that TanNmH+ and TanNm+ are produced through successive reactions; a pure nitride and three H2 molecules are formed for every other NH3 molecule. The nitridation occurred until the formal oxidation number of tantalum atoms reaches +5 as in the case of TaN2H2+. These reaction pathways of tantalum atom and cluster cations are in contrast to those of other group 5 elements, i.e., vanadium and niobium cluster cations, which have been reported to produce nitrides with lower oxidation states [5,6]. The present results on nitridation of small clusters illustrate correlation with their bulk properties: Tantalum is known to form bulk nitrides in the oxidation states of either +5 (Ta3N5) or +3 (TaN), whereas vanadium and niobium form only an oxidation state of +3 (VN and NbN) [7]. Along with DFT calculations, these findings reveal that electronegativity of the metal (V > Nb > Ta) plays a key role in determining the composition of metal nitrides. In contrast to nitrides, all of vanadium, niobium and tantalum form most stable oxides in the oxidation state of +5 due to high electronegativity of oxygen compared with nitrogen. The present study thus revealed that electronegativity of group 5 metal is crucial for nitridation..
3. M. Arakawa, G. Naresh Patwari, and A. Terasaki, Nitridation mechanism of tantalum cluster cations by ammonia molecules: contrast to other group 5 metals, Gas Phase Model Systems for Catalysis – GPMC 2018, 2018.06, Tantalum nitride is an attractive material with a potential for various applications such as photocatalysts for H2 evolution from water and copper diffusion barriers in microelectronics. Elucidation of nitridation mechanism of tantalum at the molecular level would supply a useful recipe for fabricating high-quality tantalum-nitride materials. In the present study, reactions of free tantalum cation, Ta+, and tantalum cluster cations, Tan+, with ammonia molecules were investigated to probe nitridation reactions step by step with precise control in the number of atoms and molecules involved in the reaction [1].
In the experiment, Tan+ (n = 1–10) was generated by a magnetron-sputter cluster-ion source. They were thermalized through collisions with helium molecules cooled by liquid nitrogen, and were mass-selected and guided into a reaction cell filled with NH3 molecules. The ions produced by the reaction were identified by a quadrupole mass analyzer, and the yield of each reaction product was measured as a function of the cluster size, n.
The reaction of monomer cation, Ta+, with two molecules of NH3 leads to formation of TaN2H2+ along with release of two H2 molecules. The dehydrogenation occurs until the formal oxidation number of the tantalum atom reaches +5. On the other hand, all the tantalum cluster cations, Tan+, react with two molecules of NH3 and form TanN2+ with the release of three H2 molecules. Further exposure to ammonia showed that TanNmH+ and TanNm+ are produced through successive reactions; this is achieved by alternate single and double dehydrogenation upon adsorption of every other NH3 reactant molecule. The nitridation occurred until the formal oxidation number of tantalum atoms reaches +5 as in the case of TaN2H2+. These reaction pathways of tantalum atom and cluster cations are in contrast to those of other group 5 metals, i.e., vanadium and niobium clusters, which have been reported to produce nitrides with lower oxidation states [2,3]. The present results on nitridation of small clusters of group 5 metals illustrate correlation with their bulk properties: Tantalum is known to form bulk nitrides in the oxidation states of either +5 (Ta3N5) or +3 (TaN), whereas vanadium and niobium form only an oxidation state of +3 (VN and NbN) [4]. Along with DFT calculations, these findings reveal that nitridation is driven by the electron-donating ability of the group 5 element, i.e., electronegativity of the metal plays a significant role in determining the composition of metal nitrides..
4. M. Arakawa, Application of cluster chemistry to astrochemistry: Molecular evolution involving mineral clusters, Kaleidoscope: A Discussion Meeting in Chemistry, 2018.07.
5. Masashi Arakawa, Reaction of silicate clusters related to chemistry in the interstellar environment, International Symposium on Molecular Science -Physical Chemistry/ Theoretical Chemistry, Chemoinformatics, Computational Chemistry-,, 2018.03.
6. Masashi Arakawa, Ryo Yamane, Akira Terasaki, Reaction site of a CO molecule on silicon-oxide cluster anions, Symposium on Size Selected Clusters, 2016.02.
7. Masashi Arakawa, Ryo Yamane, Akira Terasaki, Adsorption of a CO molecule on silicon-oxide cluster anions toward elucidation of reaction processes on mineral surfaces in proto-planetary nebulae, PACIFICHEM 2015, 2015.12.
8. Masashi Arakawa, Ryo Yamane, Akira Terasaki, Reaction sites of a CO molecule on silicon-oxide cluster anions as a model of mineral surfaces, Workshop on Nanoscale Atomic and Molecular Systems, 2015.08.
9. Masashi Arakawa, Kei Kohara, Akira Terasaki, Formation of hydrated-alumina clusters toward elucidation of generation process of organic molecules on mineral surfaces, Workshop on Interstellar Matter, 2014.10.
10. Masashi Arakawa, Kei Kohara, Akira Terasaki, Dissociation, oxidation, hydroxylation, and hydration of aluminum cluster cations upon reaction with H2O and O2, Gas Phase Model Systems for Catalysis – GPMC 2014, 2014.04.
11. Masashi Arakawa, Kei Kohara, Akira Terasaki, Formation of stable aluminum hydroxide clusters in aluminum-cluster ion beam exposed to O2 and H2O, Trombay Symposium on Radiation and Photochemistry, 2014.01.
Membership in Academic Society
  • Society of Nano Science and Technology
  • The Chemical Society of Japan
  • Japan Society for Molecular Science
  • The Japanese Society for Planetary Sciences
  • The Japanese Society of Snow and Ice