Researcher Profile and Settings

Master

Affiliation (Master)

• Institute of Low Temperature Science　Frontier Ice and Snow Science

Affiliation (Master)

• Institute of Low Temperature Science　Frontier Ice and Snow Science

researchmap

Profile and Settings

Affiliation

• Hokkaido University, Institute of Low Temperature Science, Frontier Ice and Snow Science, Assistant Professor

Profile and Settings

• Name (Japanese)

  Hidaka

• Name (Kana)

  Hiroshi

• Name

  200901004379035152

Affiliation

• Hokkaido University, Institute of Low Temperature Science, Frontier Ice and Snow Science, Assistant Professor

Achievement

Research Interests

• 星間塵   低温表面反応   REMPI   水素分子   反応熱   星間化学   惑星間空間   重水素濃集   低温   原子反応   地球外物質化学   氷表面反応   表面   アモルファス氷   トンネル反応   極低温表面反応   同位体分別   星間分子   

Research Areas

• Natural sciences / Space and planetary science
• Natural sciences / Solid earth science

Research Experience

• 2012 Hokkaido University Institute of Low Temperature Science

Education

•        - 2003  Tokyo Metropolitan University  Graduate School of Science  Department of Physics
•        - 2003  Tokyo Metropolitan University  Graduate School, Division of Natural Science
•        - 2000  Tokyo Metropolitan University  Graduate School of Science
•        - 2000  Tokyo Metropolitan University  Graduate School, Division of Natural Science
•        - 1998  Hosei University
•        - 1998  Hosei University  Faculty of Engineering

Published Papers

• Determination of the Branching Ratio of CH3OH + OH Reaction on Water Ice Surface at 10 K

  Atsuki Ishibashi, Hiroshi Hidaka, W. M. C. Sameera, Yasuhiro Oba, Naoki Watanabe

  The Astrophysical Journal 2024/01/01 [Refereed]
  
• Methanol Formation through Reaction of Low-energy CH3 + Ions with an Amorphous Solid Water Surface at Low Temperature

  Y. Nakai, W. M. C. Sameera, K. Furuya, H. Hidaka, A. Ishibashi, N. Watanabe

  The Astrophysical Journal 2023/08/01
• A systematic mechanistic survey on the reactions between OH radical and CH₃OH on ice

  W. M. C. Sameera, Avon P. Jayaweera, Atsuki Ishibashi, Hiroshi Hidaka, Yasuhiro Oba, Naoki Watanabe

  Faraday Discussions 245 508 - 518 1359-6640 2023 

  Our systematic computational study suggests that the nature of the binding site or the reaction site has a significant effect on the computed binding energies or reaction barriers.
• Direct Determination of the Activation Energy for Diffusion of OH Radicals on Water Ice

  A. Miyazaki, M. Tsuge, H. Hidaka, Y. Nakai, N. Watanabe

  The Astrophysical Journal Letters 940 (1) L2 - L2 2041-8205 2022/11/14 [Refereed][Not invited]
   

  Abstract Using a combination of photostimulated desorption and resonance-enhanced multiphoton ionization methods, the behaviors of OH radicals on the surface of an interstellar ice analog were monitored at temperatures between 54 and 80 K. The OH number density on the surface of ultraviolet-irradiated compact amorphous solid water gradually decreased at temperatures above 60 K. Analyzing the temperature dependence of OH intensities with the Arrhenius equation, the decrease can be explained by the recombination of two OH radicals, which is rate-limited by thermal diffusion of OH. The activation energy for surface diffusion was experimentally determined for the first time to be 0.14 ± 0.01 eV, which is larger than or equivalent to those assumed in theoretical models. This value implies that the diffusive reaction of OH radicals starts to be activated at approximately 36 K on interstellar ice.
• Modelling the Radical Chemistry on Ice Surfaces: An Integrated Quantum Chemical and Experimental Approach

  W. M. C. Sameera, Bethmini Senevirathne, Thanh Nguyen, Yasuhiro Oba, Atsuki Ishibashi, Masashi Tsuge, Hiroshi Hidaka, Naoki Watanabe

  Frontiers in Astronomy and Space Sciences 9 2022/05/30 

  Heterogeneous radical processes on ice surfaces play a vital role in the formation of building blocks of the biologically relevant molecules in space. Therefore, quantitative mechanistic details of the radical binding and radical reactions on ices are crucial in rationalizing the chemical evolution in the Universe. The radical chemistry on ice surfaces was explored at low temperatures by combining quantum chemical calculations and laboratory experiments. A range of binding energies was observed for OH, HCO, CH₃, and CH₃O radicals binding on ices. Computed reaction paths of the radical reactions on ices, OCS + H and PH₃ + D, explained the experimentally observed products. In both radical reactions, quantum tunnelling plays a key role in achieving the reactions at low temperatures. Our findings give quantitative insights into radical chemistry on ice surfaces in interstellar space and the planetary atmospheres.
• UV-Induced Formation of Ice XI Observed Using an Ultra-High Vacuum Cryogenic Transmission Electron Microscope and its Implications for Planetary Science

  Akira Kouchi, Yuki Kimura, Kensei Kitajima, Hiroyasu Katsuno, Hiroshi Hidaka, Yasuhiro Oba, Masashi Tsuge, Tomoya Yamazaki, Kazuyuki Fujita, Tetsuya Hama, Yukihiro Takahashi, Shunichi Nakatsubo, Naoki Watanabe

  Frontiers in Chemistry 9 2021/12/08 

  The occurrence of hydrogen atom-ordered form of ice Ih, ice XI, in the outer Solar System has been discussed based on laboratory experiments because its ferroelectricity influences the physical processes in the outer Solar System. However, the formation of ice XI in that region is still unknown due to a lack of formation conditions at temperatures higher than 72 K and the effect of UV-rays on the phase transition from ice I to ice XI. As a result, we observed the UV-irradiation process on ice Ih and ice Ic using a newly developed ultra-high vacuum cryogenic transmission electron microscope. We found that ice Ih transformed to ice XI at temperatures between 75 and 140 K with a relatively small UV dose. Although ice Ic partially transformed to ice XI at 83 K, the rate of transformation was slower than for ice Ih. These findings point to the formation of ice XI at temperatures greater than 72 K via UV irradiation of ice I crystals in the Solar System; icy grains and the surfaces of icy satellites in the Jovian and Saturnian regions.
• Efficient Formation Pathway of Methyl Formate: The Role of OH Radicals on Ice Dust

  A. Ishibashi, H. Hidaka, Y. Oba, A. Kouchi, N. Watanabe

  The Astrophysical Journal Letters 2021/11/01 [Refereed]
  
• Transmission Electron Microscopy Study of the Morphology of Ices Composed of H2O, CO2, and CO on Refractory Grains

  Akira Kouchi, Masashi Tsuge, Tetsuya Hama, Yasuhiro Oba, Satoshi Okuzumi, Sin-iti Sirono, Munetake Momose, Naoki Nakatani, Kenji Furuya, Takashi Shimonishi, Tomoya Yamazaki, Hiroshi Hidaka, Yuki Kimura, Ken-ichiro Murata, Kazuyuki Fujita, Shunichi Nakatsubo, Shogo Tachibana, Naoki Watanabe

  The Astrophysical Journal 918 (2) 45 - 45 0004-637X 2021/09/01 [Refereed]
  
• CH3O Radical Binding on Hexagonal Water Ice and Amorphous Solid Water

  W. M. C. Sameera, Bethmini Senevirathne, Stefan Andersson, Muhsen Al-lbadi, Hiroshi Hidaka, Akira Kouchi, Gunnar Nyman, Naoki Watanabe

  The Journal of Physical Chemistry A 125 (1) 387 - 393 1089-5639 2021/01/14 [Refereed]
  
• Delivery of Electrons by Proton-Hole Transfer in Ice at 10 K: Role of Surface OH Radicals

  Kensei Kitajima, Yoichi Nakai, W. M. C. Sameera, Masashi Tsuge, Ayane Miyazaki, Hiroshi Hidaka, Akira Kouchi, Naoki Watanabe

  The Journal of Physical Chemistry Letters 12 (1) 704 - 710 1948-7185 2021/01/14 [Refereed]
  
• Photostimulated desorption of OH radicals from amorphous solid water: Evidence for the interaction of visible light with an OH-ice complex

  A. Miyazaki, N. Watanabe, W. M. C. Sameera, Y. Nakai, M. Tsuge, T. Hama, H. Hidaka, A. Kouchi

  Physical Review A 102 (5) 2469-9926 2020/11/20 [Refereed]
  
• Diffusive Hydrogenation Reactions of CO Embedded in Amorphous Solid Water at Elevated Temperatures ∼70 K

  Masashi Tsuge, Hiroshi Hidaka, Akira Kouchi, Naoki Watanabe

  The Astrophysical Journal 900 (2) 187 - 187 2020/09/15 [Refereed]
  
• Formation experiments of organic molecules by catalytic reactions in low-temperature and low-pressure environments

  Yuki Kimura, Rikako Sato, AkiraTsuchiyama, YusukeTamenori, Tetsuya Hama, Hiroshi Hidaka, Naoki Watanabe, Akira Kouchi, Hiroko Nagahara

  Low Temperature Science 78 79 - 90 2020/03 [Refereed]
  
• Ultraviolet-photon exposure stimulates negative current conductivity in amorphous ice below 50 K

  N. Watanabe, W. M. C. Sameera, H. Hidaka, A. Miyazaki, A. Kouchi

  Chemical Physics Letters 737 136820  2019 [Refereed][Not invited]
  
• 超高真空極低温透過型電子顕微鏡の開発─氷のその場観察をめざして─

  香内晃, 日高宏, 羽馬哲也, 木村勇気, 渡部直樹, 中坪俊一, 藤田和之, 新堀邦夫, 池田正幸

  日本雪氷学会誌 雪氷 in press 2018 [Refereed][Not invited]
  
• Liquid-like behavior of UV-irradiated interstellar ice analog at low temperatures.

  Shogo Tachibana, Akira Kouchi, Tetsuya Hama, Yasuhiro Oba, Laurette Piani, Iyo Sugawara, Yukiko Endo, Hiroshi Hidaka, Yuki Kimura, Ken-Ichiro Murata, Hisayoshi Yurimoto, Naoki Watanabe

  Science advances 3 (9) eaao2538  2017/09 [Refereed][Not invited]
   

  Interstellar ice is believed to be a cradle of complex organic compounds, commonly found within icy comets and interstellar clouds, in association with ultraviolet (UV) irradiation and subsequent warming. We found that UV-irradiated amorphous ices composed of H2O, CH3OH, and NH3 and of pure H2O behave like liquids over the temperature ranges of 65 to 150 kelvin and 50 to 140 kelvin, respectively. This low-viscosity liquid-like ice may enhance the formation of organic compounds including prebiotic molecules and the accretion of icy dust to form icy planetesimals under certain interstellar conditions.
• Simulations and spectra of water in CO matrices

  Rafael Escribano, Emilio Artacho, Akira Kouchi, Tetusya Hama, Yuki Kimura, Hiroshi Hidaka, Naoki Watanabe

  PHYSICAL CHEMISTRY CHEMICAL PHYSICS 19 (10) 7280 - 7287 1463-9076 2017/03 [Refereed][Not invited]
   

  Models for the inclusion of water molecules in carbon monoxide matrices are developed using density functional theory applied to amorphous solid systems. The models cover a large range of systems for smaller or larger CO matrices with different water content, consisting of either individual H2O molecules or small clusters linked by H-bonds. The vibrational spectra of the samples are predicted at the minimum of their potential energy surface. The spectra allow instances where the water molecules remain isolated or form aggregates to be discerned, and they also provide an indication of the strength of the H-bonding, when present. The calculations support recent experimental observations that linked IR bands at 3707 cm(-1) and 3617 cm(-1) to the presence of unbound water molecules in water-poor CO/H2O mixed ices. Assignment of some observed bands to water dimers or trimers is suggested as well. The residual static pressure in fixed-volume simulation cells is also calculated.
• Hydrogenation and Deuteration of C2H2 and C2H4 on Cold Grains: A Clue to the Formation Mechanism of C2H6 with Astronomical Interest

  Hitomi Kobayashi, Hiroshi Hidaka, Thanja Lamberts, Tetsuya Hama, Hideyo Kawakita, Johannes Kaestner, Naoki Watanabe

  ASTROPHYSICAL JOURNAL 837 (2) 155 - 169 0004-637X 2017/03 [Refereed][Not invited]
   

  We quantitatively investigated the hydrogen addition reactions of acetylene (C2H2) and ethylene (C2H4) on amorphous solid water (ASW) at 10 and 20 K relevant to the formation of ethane (C2H6) on interstellar icy grains. We found that the ASW surface enhances the reaction rates for C2H2 and C2H4 by approximately a factor of 2 compared to those on the pure- solid C2H2 and C2H4 at 10 K, probably due to an increase in the sticking coefficient and adsorption energy of the H atoms on ASW. In contrast to the previous proposal that the hydrogenation rate of C2H4 is orders of magnitude larger than that of C2H2, the present results show that the difference in hydrogenation rates of C2H2 and C2H4 is only within a factor of 3 on both the surfaces of pure solids and ASW. In addition, we found the small kinetic isotope effect for hydrogenation/deuteration of C2H2 and C2H4 at 10 K, despite the requirement of quantum tunneling. At 20 K, the reaction rate of deuteration becomes even larger than that of hydrogenation. These unusual isotope effects might originate from a slightly larger number density of D atoms than H atoms on ASW at 20 K. The hydrogenation of C2H2 is four times faster than CO hydrogenation and can produce C2H6 efficiently through C2H4 even in the environment of a dark molecular cloud.
• Matrix sublimation method for the formation of high-density amorphous ice

  A. Kouchi, T. Hama, Y. Kimura, H. Hidaka, R. Escribano, N. Watanabe

  CHEMICAL PHYSICS LETTERS 658 287 - 292 0009-2614 2016/08 [Refereed][Not invited]
   

  A novel method for the formation of amorphous ice involving matrix sublimation has been developed. A CO-rich CO:H2O mixed ice was deposited at 8-10 K under ultra-high vacuum condition, which was then allowed to warm. After the sublimation of matrix CO at 35 K, amorphous ice remained. The amorphous ice formed exhibits a highly porous microscale texture; however, it also rather exhibits a density similar to that of high-density amorphous ice formed under high pressure. Furthermore, unlike conventional vapor-deposited amorphous ice, the amorphous ice is stable up to 140 K, where it transforms directly to cubic ice Ic. (C) 2016 Elsevier B.V. All rights reserved.
• Stepwise formation of H3O+(H2O)(n) in an ion drift tube: Empirical effective temperature of association/dissociation reaction equilibrium in an electric field

  Yoichi Nakai, Hiroshi Hidaka, Naoki Watanabe, Takao M. Kojima

  JOURNAL OF CHEMICAL PHYSICS 144 (22) 224306  0021-9606 2016/06 [Refereed][Not invited]
   

  We measured equilibrium constants for H3O+(H2O)(n-1) + H2O <-> H3O+(H2O)(n) (n = 4-9) reactions taking place in an ion drift tube with various applied electric fields at gas temperatures of 238-330 K. The zero-field reaction equilibrium constants were determined by extrapolation of those obtained at non-zero electric fields. From the zero-field reaction equilibrium constants, the standard enthalpy and entropy changes, Delta H-n,n-1(0) and Delta S-n, n-1(0), of stepwise association for n = 4-8 were derived and were in reasonable agreement with those measured in previous studies. We also examined the electric field dependence of the reaction equilibrium constants at non-zero electric fields for n = 4-8. An effective temperature for the reaction equilibrium constants at non-zero electric field was empirically obtained using a parameter describing the electric field dependence of the reaction equilibrium constants. Furthermore, the size dependence of the parameter was thought to reflect the evolution of the hydrogen-bond structure of H3O+(H2O)(n) with the cluster size. The reflection of structural information in the electric field dependence of the reaction equilibria is particularly noteworthy. Published by AIP Publishing.
• 21pBG-3 Reaction equilibria for stepwise formation of H_3O(H_2O)_n^+ cluster ions in an electric field of an ion drift tube

  Nakai Yoichi, Hidaka Hiroshi, Watanabe Naoki, Kojima Takao M.

  Meeting Abstracts of the Physical Society of Japan 一般社団法人日本物理学会 70 632 - 632 2189-079X 2015
• Formation of deuterated formaldehyde on low temperature surfaces: isotope effect of quantum tunneling reactions

  H. Hidaka, M. Watanabe, A. Kouchi, N. Watanabe

  FIRST INTERNATIONAL CONFERENCE ON CHEMICAL EVOLUTION OF STAR FORMING REGION AND ORIGIN OF LIFE (ASTROCHEM2012) 1543 318 - 325 0094-243X 2013 [Refereed][Not invited]
   

  The elucidation of formation pathways and mechanisms of deuterated species that have been detected by astronomical observations is important in studying chemical evolution in space. Formaldehyde and methanol are well-known molecules not only as reaction products on grain surfaces, but also as highly deuterated molecules. We have conducted experimental studies to clarify the formation mechanisms of deuterated formaldehyde and methanol on low temperature solid surfaces. In this paper, we summarize our experimental findings of the exposure of solid H2CO and D2CO on amorphous solid water to D and H atoms at 10-20 K, respectively. The isotope exchange reactions were observed in both reaction systems of D + H2CO and H + D2CO. In contrast, the addition reactions were only observed in the H + D2CO system because D addition to H2CO is much slower than isotope exchange. This isotope dependence on the reaction pathways can be explained by the quantum tunneling effect.
• Water formation through a quantum tunneling surface reaction, OH + H 2, at 10K

  Y. Oba, N. Watanabe, T. Hama, K. Kuwahata, H. Hidaka, A. Kouchi

  Astrophysical Journal 749 (1) 67 - 78 1538-4357 2012/04/10 [Refereed][Not invited]
   

  The present study experimentally demonstrated that solid H2O is formed through the surface reaction OH+ H2 at 10K. This is the first experimental evidence of solid H2O formation using hydrogen in its molecular form at temperatures as low as 10K. We further found that H 2O formation through the reaction OH+ H2 is about one order of magnitude more effective than HDO formation through the reaction OH+ D2. This significant isotope effect results from differences in the effective mass of each reaction, indicating that the reactions proceed through quantum tunneling. © 2012. The American Astronomical Society. All rights reserved.
• 星間分子雲での微粒子表面における水素の化学物理過程

  渡部直樹, 香内晃, 羽馬哲也, 日高宏, 大場康弘, 千貝健

  表面科学 33 (12) 662 - 668 0388-5321 2012 [Not refereed][Not invited]
  
• FTIR study of ammonia formation via the successive hydrogenation of N atoms trapped in a solid N_2 matrix at low temperatures

  HIDAKA H.

  Physical Chemistry Chemical Physics 13 (35) 15798 - 15802 1463-9076 2011 [Refereed][Not invited]
  
• Formation of ammonia molecules by H addition reactions to N atom on interstellar grain surfaces at low temperatures

  Hidaka Hiroshi, Kouchi Akira, Watanabe Naoki

  Abstracts of Annual Meeting of the Geochemical Society of Japan 日本地球化学会 58 292 - 292 2011 

  分子雲でアンモニア分子が生成される過程として提案されている，低温星間塵表面における窒素原子への水素原子付加反応の検証を実験的手法により行った．実験は，超高真空槽内に設置した低温基板（10K）にNおよびH原子を照射し，赤外吸収分光により生成分子の観測を行った．その結果，10Kという低温表面でも上記表面反応によりアンモニアが生成されることが明らかになった．
• Formation of H2O Ice through the Surface Reaction O2 + H at Low Temperatures: Reaction Kinetics and Structure of the Ice

  Oba, Y, Miyauchi, N, Chigai, T, Hidaka, H, Watanabe, N, Kouchi, A

  Physics and Chemistry of Ice 2010, eds. Y. Furukawa, G. Sazaki, T. Uchida, N. Watanabe, Hokkaido University Press, Sapporo, ISBN: 978-4-8329-0361-6 361 - 368 2011 [Not refereed][Not invited]
  
• Sequential hydrogenation of molecular oxygen on cold surfaces: reaction kinetics and structure of formed H2O ice

  Y.Oba, N.Miyauchi, H.Hidaka, T.Chigai, N.Watanabe, A.Kouchi

  Proceedings of the International Astronomical Union 280 2011 [Refereed][Not invited]
  
• Formation of amorphous H₂O ice from the reactions of cold H atoms with solid O₂ at 10 K

  A. Kouchi, N. Watanabe, H. Hidaka, N. Miyauchi, Y. Oba, T. Chigai

  Astron. Soc. Pacific Conf. Ser. 414 338 - 346 2010 [Refereed][Not invited]
  
• Physicochemical processes of atomic hydrogen on amorphous solid water at very low temperatures

  Watanabe Naoki, Kouchi Akira, Hidaka Hiroshi, Kimura Yuki, Hama Tetsuya

  Abstracts of Papers of the American Chemical Society 239 2010 [Refereed][Not invited]
  
• Hydrogen isotope exchange and H(D) atom addition reaction of solid formaldehyde on amorphous solid water at low temperatures

  Hiroshi Hidaka, Motohiro Watanabe, Akira Kouchi, Naoki Watanabe

  Journal of Physics: Conference Series 194 (13) 132024  1742-6596 2009/12/24 [Not refereed][Not invited]
   

  Reaction routes when H2CO and D2CO were exposed to the D and H atoms on amorphous solid water (ASW) at 10-20 K, respectively, were studied experimentally by IR spectroscopy. For D + H2CO on ASW, H2CO was converted to HDCO and D2CO by the H-D substitution reactions. Although CD3OD was slightly observed, doubly- and triply-deuterated methanol, CH2DOD and CHD2OD, were not observed. This implies that the D additions to H2CO (formation of deuterated methanol) is a minor reaction route. On the other hand, for H + D2CO, H addition reactions to form CHD2OH proceed significantly as much as conversions to HDCO and H2CO, which evolve to CH2DOH and CH3OH by the further H additions, respectively. Therefore, in this reaction system, two kind of reaction routes for D2CO HDCO H2CO CH3OH and D2CO CHD2OH are competitive.
• REACTION ROUTES IN THE CO-H2CO-d(n)-CH3OH-d(m) SYSTEM CLARIFIED FROM H(D) EXPOSURE OF SOLID FORMALDEHYDE AT LOW TEMPERATURES

  H. Hidaka, M. Watanabe, A. Kouchi, N. Watanabe

  ASTROPHYSICAL JOURNAL 702 (1) 291 - 300 0004-637X 2009/09 [Refereed][Not invited]
   

  Grain surface reaction has been expected to be a key process for deuterium enrichment in interstellar molecules. We focus on formaldehyde, which is predicted to be formed on cold grain surface in astrophysical models and is known to be deuterium-enriched in a molecular cloud. Reaction routes and effective reaction rate constants are experimentally investigated when H2CO and D2CO are exposed to D and H atoms on amorphous solid water (ASW) at 10-20 K, respectively. For D + H2CO on ASW, H2CO was converted to HDCO and D2CO by the H-D substitution reactions. Although CD3OD was slightly observed, doubly and triply deuterated methanol, CH2DOD and CHD2OD, were not observed. This implies that D addition to H2CO (formation of deuterated methanol) is a minor reaction route. On the other hand, for H + D2CO, H addition reactions to form CHD2OH proceed at a significant rate. Simultaneously, a competitive reaction, the substitution reaction by H atoms and subsequent H addition (D2CO -> HDCO -> H2CO -> CH3OH) also proceed at a significant rate. However, no H addition to HDCO was observed. The effective surface reaction routes when CO is exposed to H and D atoms are summarized using the present experimental results and the previous results of our group.
• FORMATION OF COMPACT AMORPHOUS H2O ICE BY CODEPOSITION OF HYDROGEN ATOMS WITH OXYGEN MOLECULES ON GRAIN SURFACES

  Y. Oba, N. Miyauchi, H. Hidaka, T. Chigai, N. Watanabe, A. Kouchi

  ASTROPHYSICAL JOURNAL 701 (1) 464 - 470 0004-637X 2009/08 [Refereed][Not invited]
   

  Formation of H2O molecules through the codeposition of oxygen molecules and hydrogen atoms is examined in situ using IR spectroscopy at 10-40 K under various O-2 and H fluxes. It is found that H2O and H2O2 are continuously formed by reaction, even at 40 K. The H2O ice formed is amorphous, but has a compact (not microporous) structure compared to vapor-deposited amorphous H2O ice, because dangling OH bonds are not observed in the IR spectrum. This is consistent with astronomical observations in molecular clouds and theoretical predictions, which suggest that hydrogenation of O-2 is one of the potential routes for reproducing these IR spectral characteristics. The composition of the ice formed by codeposition varies with the O-2/H ratio and temperature. Although no data are available at present for the H2O/H2O2 ratio of ice in molecular clouds, this study suggests that hydrogenation of O-2 has a potential to yield a H2O/H2O2 ratio of 5 or more in molecular clouds.
• Hydrogen isotope exchange and H(D) atom addition reaction of solid formaldehyde on amorphous solid water at low temperatures

  H. Hidaka, M. Watanabe, A. Kouchi, N. Watanabe

  Journal of physics: Conference series 194 132024  2009 [Refereed][Not invited]
  
• Formation of CO2 molecules by a surface reaction CO+OH at low temperatures.

  OBA Yasuhiro, WATANABE Naoki, HIDAKA Hiroshi, KOUCHI Akira, PIRRONELLO Varelio

  Abstracts of Annual Meeting of the Geochemical Society of Japan 日本地球化学会 56 66 - 66 2009 

  二酸化炭素は分子雲中星間塵アイスマントルの主要な構成成分であるが、気相反応によってその存在量を説明することができないため、その生成には塵表面での反応が重要だと考えられている。これまでの研究では、UVなどの外部エネルギーをH2OやCOなどを含む混合氷に照射してCO2生成が確認されてきたが、外部エネルギー無しにCO2が生成するかどうかは明らかにされていなかった。本講演では、100Kに冷却されたOHラジカルとCOの固体表面上での反応でCO2生成が確認されたので、その結果について報告する。
• Formation of water molecule by surface atomic reactions on interstellar grains at low temperatures

  OBA Yasuhiro, MIYAUCHI Naoya, CHIGAI Takeshi, HIDAKA Hiroshi, WATANABE Naoki, KOUCHI Akira

  Chikyukagaku 日本地球化学会 43 (4) 117 - 131 0386-4073 2009 [Refereed][Not invited]
   

  Formation of water by reaction of oxygen molecules (O₂) with hydrogen atoms (H) were investigated at low temperatures (10-40 K) in order to reveal the possible reaction pathways to yield water on grain surfaces in molecular clouds. Two types of experiments for surface reaction between O₂ and H were performed: one of which was that solid O₂ was deposited onto the surface, followed by H irradiations to the O₂, another of which was that gaseous O₂ was continuously codeposited with H onto the surface and was reacted with each other. H₂O (D₂O) and H₂O₂ (D₂O₂) were quickly produced through successive reactions of O₂ with H (D). Reaction kinetics and isotope effect are discussed for the former experiment. For the latter experiment, the dependence of compositions of the products on the temperature and O₂/H ratio, and also the structure of the H₂O ice produced are examined.
• Nonenergetic reactions between atomic hydrogen and molecules on interstellar grain surfaces

  N. Watanabe, A. Kouchi, H. Hidaka, Y. Oba, N. Miyauchi

  Journal of Physics: Conference Series 194 (1) 012044  1742-6596 2009 [Refereed][Not invited]
   

  Reactions of atomic hydrogen with CO and O2 on amorphous solid water (ASW), relevant to chemical evolution on cosmic ice dust, were experimentally investigated at around 10 K. Successive addition of hydrogen atoms to CO and O2 produces H2CO, CH3OH, and H2O2, H2O, respectively. At such low temperatures, some of hydrogen additions such as H + CO HCO proceed via tunneling reactions rather than thermally-activated reactions. Effective reaction rates and isotope effect of the tunneling reactions to produce HCO and H2O were measured. The surface of ASW was found to enhance the effective rate of hydrogen addition to CO at relatively higher temperatures, namely around 20 K. © 2009 IOP Publishing Ltd.
• 1. Formation of interstellar ice by low temperature surface atomic reactions

  A. Kouchi, Y. Oba, N. Miyauchi, H. Hidaka, N. Watanabe

  Cryobiology Elsevier {BV} 59 (3) 370  2009 [Refereed][Not invited]
  
• 332 極低温表面原子反応O₂+Hによる水分子生成 : アモルファス氷の触媒効果(原始惑星系円盤II,オーラルセッション11)

  大場 康弘, 宮内 直弥, 千貝 健, 日高 宏, 渡部 直樹, 香内 晃

  日本惑星科学会秋期講演会予稿集 日本惑星科学会 2008 (0) 93 - 93 2008/11 [Not refereed][Not invited]
  
• Structural effects of ice grain surfaces on the hydrogenation of CO at low temperatures

  H. Hidaka, N. Miyauchi, A. Kouchi, N. Watanabe

  Chemical Physics Letters 456 (1-3) 36 - 40 0009-2614 2008/04/21 [Refereed][Not invited]
   

  Experiments on the hydrogenation of CO on crystalline and amorphous ice at 15 K were carried out to investigate the structural effects of the ice surface. The effective rate of H atom addition to CO on the amorphous ice was found to be larger than that on the crystalline ice, while CO depletion on crystalline ice became larger after long exposure. We demonstrated that the CO-coverage on the ice surfaces dominates the effective reaction rate rather than the surface structure. The larger depletion of CO on crystalline ice, as compared to amorphous ice, suggests easier desorption of CO and/or products by the heat of the reaction. © 2008 Elsevier B.V. All rights reserved.
• Formation of hydrogen peroxide and water from the reaction of cold hydrogen atoms with solid oxygen at 10 K

  N. Miyauchi, H. Hidaka, T. Chigai, A. Nagaoka, N. Watanabe, A. Kouchi

  CHEMICAL PHYSICS LETTERS 456 (1-3) 27 - 30 0009-2614 2008/04 [Refereed][Not invited]
   

  The reactions of cold H atoms with solid O-2 molecules were investigated at 10 K. The formation of H2O2 and H2O has been confirmed by in situ infrared spectroscopy. We found that the reaction proceeds very efficiently and obtained the effective reaction rates. This is the first clear experimental evidence of the formation of water molecules under conditions mimicking those found in cold interstellar molecular clouds. Based on the experimental results, we discuss the reaction mechanism and astrophysical implications. (C) 2008 Elsevier B.V. All rights reserved.
• Formation of water from surface-atomic reactions at low temperatures

  OBA YASUHIRO, MIYAUCHI NAOYA, CHIGAI TAKESHI, HIDAKA HIROSHI, WATANABE NAOKI, KOUCHI AKIRA

  Abstracts of Annual Meeting of the Geochemical Society of Japan 日本地球化学会 55 371 - 371 2008 

  水分子は星間塵アイスマントル中で最も多く存在する分子であるが、その生成メカニズムはいまだはっきりしない。本研究では星間塵上表面原子反応による水分子生成反応の検証を行った。酸素分子を10Kに冷却された基板上に蒸着させ、そこに水素分子をプラズマ解離させて生成する水素原子を照射した。水素原子照射により酸素分子へ水素原子が付加され、過酸化水素、水の生成が確認された。これは酸素分子への水素原子逐次付加反応O2+H->HO2、HO2+H->H2O2、H2O2+H->H2O+OHが起こったことによる。
• 分子雲で生じる低温表面反応：表面実験で探る分子進化

  日高宏, 渡部直樹, 香内晃

  低温科学 66 13  2008 [Refereed][Not invited]
  
• Interstellar amorphous ice ggrain: The role in chemical evolution

  Naoki Watanabe, Akira Kouchi, Orie Mouri, Akihiro Nagaoka, Hiroshi Hidaka

  Shinku/Journal of the Vacuum Society of Japan 50 (4) 282 - 290 0559-8516 2007 [Refereed][Not invited]
   

  Surface reaction on interstellar ice grains is a key process for the chemical evolution in molecular clouds. We have performed a series of experiments to simulate the chemical evolution of the primordial CO molecule on the ice grains. Photochemical and hydrogen atom reactions of CO-H 2O binary ice at 15 K were studied because those are anticipated to be the most dominant chemical processes on the surface of grains. It was found that the photochemical reactions produce CO 2 with the highest yield, HCOOH, H 2CO, CH 3OH, and so on and that even at very low temperatures (much lower than activation energies), addition reactions of hydrogen atoms to CO proceed efficiently due to the tunneling effect and produce H 2CO and CH 3OH. Branching ratio of the yields in photochemical reactions strongly depends on the structure of ice, while hydrogen atom reactions are very sensitive to both the structure and temperature of ice. Considering the physical and chemical conditions of molecular clouds, the experimental results are consistent with the astronomical observation of ice grains.
• Temperature, composition, and hydrogen isotope effect in the hydrogenation of CO on amorphous ice surface at 10-20 K

  H. Hidaka, A. Kouchi, N. Watanabe

  Journal of Chemical Physics 126 (20) 204707  0021-9606 2007 [Refereed][Not invited]
   

  An experiment on the addition reaction of a D atom (deuteration) to CO on a cold ice surface is performed by deuterium atom exposure of three types of samples (pure solid CO, CO-capped H2 O ice, and CO- H2 O mixed ice) at 10-20 K. The variation of IR absorption spectra for the samples was measured by a Fourier transform infrared spectrometer during exposure to deuterium atoms. Reactions on pure solid CO were observed only at 10 K, while reactions on CO-capped H2 O ice and CO- H2 O mixed ice were observed to proceed even at 20 K. This indicates that the coexistence of H2 O at the surface raises the reactive temperature. In addition, the experiment on H atom exposure was also carried out at 15 K to compare the reaction rate constant between the H and D atoms. The ratio of reaction rate constant kD kH obtained is about 0.08 at 15 K. The authors provide information on the potential energy for the H+CO reaction at the surface by using the ratio kD kH and by a model calculation of the potential tunneling with the asymmetric Eckart potential. © 2007 American Institute of Physics.
• Dependence of the effective rate constants for the hydrogenation of CO on the temperature and composition of the surface

  N. Watanabe, A. Nagaoka, H. Hidaka, T. Shiraki, T. Chigai, A. Kouchi

  PLANETARY AND SPACE SCIENCE 54 (11) 1107 - 1114 0032-0633 2006/09 [Refereed][Not invited]
   

  Experiments on the hydrogenation of CO on pure CO and CO-H2O mixed ice have been performed at temperatures between 8 and 20 K. We obtained temperature and compositional dependence of the effective reaction rate constants. Results indicate that hydrogenation proceeds efficiently on pure solid CO and CO-H2O mixed ice at temperatures below 10 and 20 K, respectively. Rate constants for pure CO decreased significantly at 12 K compared to those obtained with CO-H2O mixed ice. Hydrogenation of CO at temperatures greater than 12 K were catalyzed by the H2O adjacent to the CO. The importance of the experimental results for some relevant astrophysical environments has also been outlined. (c) 2006 Elsevier Ltd. All rights reserved.
• 星間塵表面での低温水素原子反応による分子進化

  渡部直樹, 長岡明宏, 日高宏, 香内晃

  固体物理 特集号 ＜新しい水素の科学＞ 41 (1) 59 - 68 2006 [Refereed][Not invited]
  
• 星間塵表面での低温水素原子反応による分子進化

  渡部直樹, 長岡明宏, 日高宏, 香内晃

  固体物理11 41 755 - 764 2006 [Refereed][Not invited]
  
• Relative reaction rates of hydrogenation and deuteration of solid CO at very low temperatures

  Naoki Watanabe, Hiroshi Hidaka, Akira Kouchi

  AIP Conference Proceedings 855 122 - 127 0094-243X 2006 [Refereed][Not invited]
   

  Using cold atomic hydrogen and deuterium beams, hydrogenation and deuteration of solid CO on the surface of H2O ice were investigated in the surface-temperature range 8-20 K. In hydrogenation experiments, formaldehyde and methanol were produced efficiently by successive hydrogenation of CO below 20 K in conditions similar to those in molecular clouds. In deuteration experiments, we found, for the first time, that D2CO and CD3OD are formed from CO, with the reaction proceeding similarly to hydrogenation although at a much slower rate. From the attenuation curve of the parent CO at 15 K, the relative reaction rate of CO-deuteration to -hydrogenation was determined to be about 0.1. This isotope effect is considered to be due to tunneling reaction. © 2006 American Institute of Physics.
• Deuterium fractionation in the reactions of D + H2CO and H + D2CO at 15 K

  Hiroshi Hidaka, Naoki Watanabe, Akira Kouchi

  AIP Conference Proceedings 855 107 - 112 0094-243X 2006 [Refereed][Not invited]
   

  The reaction of cold H and D atoms with solid formaldehyde (D2CO and H2CO) deposited on amorphous H2O ice at 15 K was studied experimentally by in-situ FTIR spectroscopy. New routes of formation of deuterated formaldehyde (HDCO and D2CO) were identified. In the reaction of D atoms with H2CO, H-D substitution was observed, H 2CO → HDCO → D2CO, and for the reaction of H atoms with D2CO, the analogous D-H substitution was observed, D 2CO → HDCO → H2CO. In the reaction of D atoms with H2CO, the rate of H-D substitution was greater than that of formation of deuterated methanol-d2-4 by addition of 2D atoms to formaldehyde-d0-2. However, in the reaction of H atoms with D 2CO, the rate of D-H substitution was comparable to that of addition of 2H atoms to D2CO. © 2006 American Institute of Physics.
• D-enrichment in molecular clouds: H-D substitution in solid methanol

  Nagaoka Akihiro, Watanabe Naoki, Hidaka Hiroshi, Kouchi Akira

  Abstracts for Annual Meeting of the Mineralogical Society of Japan 日本鉱物科学会 2005 136 - 136 2005 

  Deuterium enrichment of interstellar methanol is reproduced experimentally for the first time via grain-surface H-D substitution in solid methanol at 10 K. The mechanism proposed here represents a key route for D-enrichment that reproduces the high observed abundances of deuterated methanol (D/H ratio of up to 0.4, compared to the cosmic ratio of about 10-5), including multiple deuterations.
• 星間塵表面反応による星間分子の重水素濃集メカニズム

  渡部直樹, 長岡明宏, 日高宏, 香内晃

  日本惑星科学会誌 14 175 - 182 2005 [Refereed][Not invited]
  
• Conversion of H2CO to CH3OH by reactions of cold atomic hydrogen on ice surfaces below 20 K

  H Hidaka, N Watanabe, T Shiraki, A Nagaoka, A Kouchi

  ASTROPHYSICAL JOURNAL 614 (2) 1124 - 1131 0004-637X 2004/10 [Refereed][Not invited]
   

  The conversion of formaldehyde (H2CO) to methanol (CH3OH) by successive hydrogenation on H2O ice was measured at 10, 15, and 20 K using atomic hydrogen beams of 30 and 300 K. The conversion rates and CH3OH yields under the 30 K beam are very similar to those under the 300 K beam at all ice temperatures, demonstrating that the reaction is independent of beam temperature. The dependence of the conversion rates on ice temperature is consistent with that for previous experiments on CO hydrogenation. The conversion rate for H2CO --> CH3OH at 15 K was found to be about half that for CO --> H2CO. The dependence of the reactions on the initial thickness of H2CO was also measured. More than 80% of H2CO was converted to CH3OH for H2CO layers of less than 1 monolayer in average thickness. Irradiation of CH3OH with H atoms did not produce H2CO, demonstrating that the reverse process, CH3OH --> H2CO (H abstraction), is minor compared to the forward process.
• 星間塵表面反応による有機分子生成および重水素濃集機構

  渡部直樹, 香内晃, 白木隆裕, 長岡明宏, 日高宏

  日本惑星科学会誌 13 226 - 232 2004 [Refereed][Not invited]
  
• Influence of ice composition on the formation on interstellar formaldehyde and methanol on dust grains

  A. Nagaoka, N. Watanabe, T. Shiraki, H. Hidaka, A. Kouchi

  Proceedings of the 37th isas luna and planetary symposium 4 91 - 94 2004 [Refereed][Not invited]
  
• Mobility of NO+ in helium gas at 77 and 4.3 K

  H Hidaka, S Jinno, H Tanuma, N Kobayashi

  JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS 36 (8) 1515 - 1524 0953-4075 2003/04 [Refereed][Not invited]
   

  The mobility of NO+ in helium has been measured at 77 and 4.3 K using a very low temperature drift tube mass spectrometer. The dependence of mobility on the reduced electric field E/N at 77 K is similar to that of rare-gas ions in helium at 82 K. The mobility measured at 4.3 K reaches a maximum at an effective temperature around 450 K and a minimum around 15 K. Below 100 K the mobility is lower than the polarization limit, which is given by the longrange polarization interaction between the ion and the neutral atom or molecule. As possible reasons for this phenomenon, the clustering reaction, the rotational excitation by the collision and the attractive r(-6) term in the interaction potential are discussed.
• Molecular ion mobility in helium gas at very low temperature

  H. Hidaka, S. Matoba, S. Jinno, H. Tanuma, N. Kobayashi

  Atomic collision research in japan -Progress report- 28 (28) 18 - 19 2002 [Refereed][Not invited]
  
• Swarm study of Kr2+ ions in helium gas at very low temperature

  H Tanuma, H Hidaka, N Kobayashi

  PHYSICS OF ELECTRONIC AND ATOMIC COLLISIONS 500 699 - 703 0094-243X 2000 [Refereed][Not invited]
   

  Doubly charged helium cluster ions Kr2+-He-n (n less than or equal to 40) have been produced when Kr2+ ions are injected into helium gas cooled by liquid helium. Magic numbers n = 12 and 32 have been observed in the size distribution of these cluster ions. These magic numbers suggest the shell structure in which an icosahedron consisting of twelve helium atoms performs as a core in the cluster ion. Not only the clustering, charge transfer between Kr2+ and He also takes place as a competitive reaction of the cluster formation. Behavior of each electronic states of the incident ions in collisions with helium have been discussed on a crude potential crossing model.

MISC

• Activation energy of OH-radical diffusion on water ice surface

  Ayane Miyazaki, Naoki Watanabe, W. M. C. Sameera, Tetsuya Hama, Hiroshi Hidaka, Akira Kouchi  ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY  258-  2019/08  [Not refereed][Not invited]
  
• Reaction experiments on H exposure of solid methanol at low temperatures

  Yukiko Yarnall, Hiroshi Hidaka, Yasuhiro Oba, Tetsuya Hama, Akira Kouchi, Naoki Watanabe  ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY  255-  2018/03  [Not refereed][Not invited]
  
• 様々な手法を用いた非晶質珪酸塩薄膜の生成実験

  土`山明, 三宅亮, 羽馬哲也, 橘省吾, 寺崎英紀, 近藤忠, 安達裕, 日高宏, 渡部直樹, 木村勇気, 香内晃  日本鉱物科学会2015年年会  2015  [Not refereed][Not invited]
  
• 27aCH-12 Current status for production of hydrated cluster ion using injected 4

  Nakai Yoichi, Hidaka Hiroshi, Watanabe Naoki, Kojima Takao M.  Meeting abstracts of the Physical Society of Japan  69-  (1)  175  -175  2014/03/05
• 27aCH-13 Formation of water cluster ions by NO^+ injection into a drift tube filled with H_2O/buffer gases : effect of the metastable NO^+

  Hidaka Hiroshi, Nakai Yoichi, Kojima Takao M., Watanabe Naoki  Meeting abstracts of the Physical Society of Japan  69-  (1)  175  -175  2014/03/05
• Role of quantum tunneling for the formation of H2O by reaction of H-2 with OH on interstellar grains

  Yasuhiro Oba, Naoki Watanabe, Tetsuya Hama, Kazuaki Kuwahata, Hiroshi Hidaka, Akira Kouchi  ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY  247-  2014/03  [Not refereed][Not invited]
  
• Current status for production of hydrated cluster ion using injected-ion drift tube 2 - production of water cluster ions

  Nakai Yoichi, Hidaka Hiroshi, Watanabe Naoki, Kojima Takao M.  Meeting abstracts of the Physical Society of Japan  68-  (2)  155  -155  2013/08/26
• Isotope effect on the surface diffusion of hydrogen atom on ASW at low temperature

  Kuwahata Kazuaki, Hama Tetsya, Hidaka Hiroshi, Kouchi Akira, Watanabe Naoki  Meeting abstracts of the Physical Society of Japan  68-  (2)  156  -156  2013/08/26
• 26aEB-5 Isotope effect on the number density of hydrogen adatom on water ice during atomic irradiation

  Kuwahata Kazuaki, Hama Tetsuya, Hidaka Hiroshi, Kouchi Akira, Watanabe Naoki  Meeting abstracts of the Physical Society of Japan  68-  (1)  182  -182  2013/03/26
• 24pAB-3 Current status for production of hydrated cluster ion using injected-ion drift tube 2 : production of water cluster ions

  Nakai Yoichi, Hidaka Hiroshi, Watanabe Naoki, Kojima Takao M.  Meeting abstracts of the Physical Society of Japan  67-  (1)  185  -185  2012/03/05
• 24pEA-1 Current status for production of hydrated cluster ion using injected-ion drift tube

  Nakai Yoichi, Hidaka Hiroshi, Watanabe Naoki, Kojima Takao M.  Meeting abstracts of the Physical Society of Japan  66-  (2)  191  -191  2011/08/24
• 28aRA-11 Ammonia formation by the successive hydrogenation of N atom in solid N_2 at low temperatures

  Hidaka Hiroshi, Kouchi Akira, Watanabe Naoki  Meeting abstracts of the Physical Society of Japan  66-  (1)  220  -220  2011/03/03
• 27pRB-6 Current status report of ion induced nucleation : Development of apparatus for production of hydrated cluster ion

  Nakai Yoichi, Hidaka Hiroshi, Watanabe Naoki, Kojima Takao M.  Meeting abstracts of the Physical Society of Japan  66-  (1)  213  -213  2011/03/03
• Laboratory investigations of physico-chemical processes occurring in icy mantles on interstellar dust grains

  V. Pirronello, M. Accolla, T. Hama, H. Hidaka, A. Kouchi, G. Manico, Y. Oba, N. Watanabe  Physics and Chemistry of ice 2010  361  -368  2011  [Refereed][Not invited]
  
• Ammonia formation by the successive hydrogenation of N atoms trapped in solid N-2 at 10 K

  Hiroshi Hidaka, Motohiro Watanabe, Akira Kouchi, Naoki Watanabe  ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY  239-  2010/03  [Not refereed][Not invited]
  
• 210 Formation of ammonia molecules by reactions of H and N atoms on the low temperature surfaces

  Hidata H., Watanabe M., Kouchi A., Watanabe N.  Abstracts Fall Meeting of the Japanese Society for Planetary Sciences  2009-  38  -38  2009/09/28
• P202 Clarification of the key routes for deuteration of formaldehyde on icy grain surface

  渡辺 元浩, 日高 宏, 渡部 直樹, 香内 晃  Abstracts Fall Meeting of the Japanese Society for Planetary Sciences  2009-  87  -87  2009/09/28
• 24aRB-6 Hydrogen atom addition reaction on surface of low temperature oxygen molecular solid

  Miyauchi N., Hidaka H., Nagaoka A., Watanabe N., Kouchi A.  Meeting abstracts of the Physical Society of Japan  63-  (1)  166  -166  2008/02/29
• 24aRB-7 Structural effects office surfaces on the hydrogenation of CO at low temperature

  Hidaka H., Miyauchi N., Kouchi A., Watanabe N.  Meeting abstracts of the Physical Society of Japan  63-  (1)  166  -166  2008/02/29
• 19pXH-6 Surface reaction of methanol molecule with deuterium atoms at 10 K

  Nagaoka A., Hidaka H., Kouchi A., Watanabe N.  Meeting abstracts of the Physical Society of Japan  62-  (1)  149  -149  2007/02/28
• 19pXH-7 Isotope effect on H/D atom addition reaction to CO on amorphous ice surfaces at low temperatures

  Hidaka H., Nagaoka A., Kouchi A., Watanabe N.  Meeting abstracts of the Physical Society of Japan  62-  (1)  149  -149  2007/02/28
• Deuterium fractionation in interstellar methanol by grain-surface reactions

  NAGAOKA Akihiro, WATANABE Naoki, HIDAKA Hiroshi, KOUCHI Akira  Planetary people  15-  (1)  4  -11  2006/03/25
• 28pYB-5 Chemical reactions on the surface of amorphous ice : chemical evolution on interstellar ice dusts

  Watanabe N., Kouchi A., Nagaoka A., Hidaka H.  Meeting abstracts of the Physical Society of Japan  61-  (1)  886  -886  2006/03/04
• Formation of Methanol by the addition of Hydrogen atoms to Formaldehyde on Formaldehyde ice

  Hidaka H., Shiraki T., Watanabe N., Kouchi A.  Meeting abstracts of the Physical Society of Japan  58-  (2)  104  -104  2003/08/15
• Molecular ion mobility in helium gas at very low temperature V

  Matoba S., Hidaka H., Tanuma H., Kobayashi N.  Meeting abstracts of the Physical Society of Japan  58-  (1)  206  -206  2003/03/06
• 26pXL-11 Molecular ion mobility in helium gas at very low temperature II

  Hidaka H., Jinno S., Tanuma H., Kobayashi N.  Meeting abstracts of the Physical Society of Japan  57-  (1)  158  -158  2002/03/01
• 26pXL-12 Mobility of O_2He_n^+ cluster ions in helium gas at very low temperature

  Jinno S., Hidaka H., Tanuma H., Kobayashi N.  Meeting abstracts of the Physical Society of Japan  57-  (1)  158  -158  2002/03/01
• Mobility of helium cluster ion in helium gas at very low temperature

  Jinno S., Hidaka H., Tanuma H., Kobayashi N.  Meeting abstracts of the Physical Society of Japan  56-  (2)  118  -118  2001/09/03
• Molecular ion mobility in helium gas at very low temperature

  Hidaka H., Jinno S., Tanuma H., Kobayashi N.  Meeting abstracts of the Physical Society of Japan  56-  (2)  117  -117  2001/09/03
• Mobility of metastable state O_2^+ in helium gas II

  Jinno S., Hidaka H., Tanuma H., Kobayashi N.  Meeting abstracts of the Physical Society of Japan  56-  (1)  138  -138  2001/03/09
• Ion mobility measurements for O_2^+ in helium gas

  Jinno S., Hidaka H., Tanuma H., Kobayashi N.  Meeting abstracts of the Physical Society of Japan  55-  (2)  94  -94  2000/09/10
• Helium cluster ion formation as a competitive process of charge transfer reaction

  Hidaka H., Jinno S., Tanuma H., Kobayashi N.  Meeting abstracts of the Physical Society of Japan  55-  (1)  69  -69  2000/03/10
• 28a-ZC-7 Study of Mobility and Cluster Formation of Kr2+ in He at Very Low Temperature II

  Hidaka H., Tanuma H., Kobayashi N.  Meeting abstracts of the Physical Society of Japan  54-  (1)  745  -745  1999/03/15
• Mobility and Cluster Formation of Kr^<2+> In He at Very Low Temperature

  HIDAKA H., TANUMA H., KOBAYASH N.  Meeting abstracts of the Physical Society of Japan  53-  (2)  883  -883  1998/09/05

Presentations

• Reactive desorption of methanol from amorphous solid water at 10K  [Invited]

  HIDAKA Hiroshi

  Cosmic dust 2019  2019/08
• Tunneling chamical reactions on low-temperature interstellar grain surfaces  [Invited]

  日髙 宏

  One-day symposium on E-ring based molecular science  2013/02
• Formation of deuterated formaldehyde on low temperature surface: isotope effect of quantum tunneling reactions  [Invited]

  日髙 宏

  ASTROCHEM2012  2012
• Formation routes of deuterated formaldehyde and methanol by tunneling reaction on amorphous solid water at 10-20K  [Invited]

  日髙 宏

  COSPAR2012  2012
• 低温氷表面での水素原子反応における氷構造の影響-アモルファスと結晶の比較-  [Invited]

  日髙 宏

  水素量子アトミクス 第6回研究会  2007/12

Association Memberships

• 日本惑星科学会   原子衝突研究協会   日本物理学会   The Japanese Society for Planetary Sciences   The Societry for Atomic Collision Research   The Physical Society of Japan   

Research Projects

• Molecular-scale elucidation of the reaction elementary processes on the model dust surfaces by single-molecule surface spectroscopy

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2020/11 -2025/03 

  Author : 今田 裕, 杉本 宜昭, 清水 智子, 金 有洙, 数間 恵弥子, 日高 宏, 香内 晃

   

  本研究では3つの研究項目（1. 塵モデル表面の作製・評価、2. 氷形成過程と構造の分子・原子レベル解明、3. 表面反応素過程の単一分子レベル解明）に分けられる。項目1では、塵表面のモデルシステムとなるケイ酸塩薄膜はパルスレーザー堆積法（PLD）装置の立上げを最初に行った。次に、チタン酸ストロンチウム(STO)基板にルテニウム酸ストロンチウム薄膜を堆積し、その構造をX線回折、原子間力顕微鏡および走査型トンネル顕微鏡を用いて評価した。PLDにおける各種パラメータに加え、STO基板の洗浄方法を最適化することでSRO薄膜の欠陥を減らせることが明らかとなった。項目2では、アモルファス氷(a-H2O)上のCO、CO2の表面拡散の活性化エネルギー(Esd)を測定した。COの場合は、porousなa-H2O上の方がcompact なa-H2O上よりもEsdが大きいことも分かった。a-H2O上に生成されるCO結晶が、a-H2Oを一様に覆うのではなく、１個のCO単結晶がa-H2Oに付着するような形態で成長することを見出した。さらに、結晶氷表面を微視的に理解することは、氷表面上の様々な化学反応を理解する重要なステップであることから、様々な基板を用いて結晶氷を作製して原子間力顕微鏡によって、その構造を原子レベルで解析した。Pt(111)およびRh(111)基板上に作成した氷は、膜厚によって積層の仕方が異なるが、表面構造は膜厚に依らず同じであった。理想表面は得られず、短距離的秩序を持つ構造が共通に得られ、定説を覆す結果となった。項目3では、星間分子の単分子反応としてAOCSを対象とし、塵モデル表面の対照実験として、Ag表面の上の吸着状態を走査トンネル顕微鏡(STM)により調べた。Ag表面上でOCSは島状構造を形成する一方、孤立分子は観察されず、紫外光または電子によってOCSが反応した様子を確認した。
• 高感度・非破壊・表面吸着分子分析装置の開発で開拓するラジカル反応研究

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Pioneering)

  Date (from‐to) : 2021/07 -2024/03 

  Author : 日高 宏

   

  本研究課題は，分子雲から原始惑星系円盤に至る天体の進化にともなって生じる，様々な有機分子の生成過程を解明するため，氷星間塵表面で生じるラジカル分子が関与する化学反応の実験研究を可能にする，高感度非破壊表面吸着分子分析装置の開発を行うことである．本分析技術の確立は，固体表面に吸着した微量分子が関与する様々な科学課題に対しても，実験による新たな研究可能領域の開拓に寄与するものである． 本装置の開発はCsイオンピックアップ法を基に，①反跳イオンの捕集効率の向上，②捕集イオンの質量分析後の異性体分離機構を導入するという方針で行う．初年度となる本年度は，まず，反跳イオンを捕集するレンズシステムの改良および，イオンが反跳する基板に対する，捕集レンズシステムの設置確度を調整できる真空槽の設計・製作を行った．これにより，現在使用している試作捕集レンズおよび設置角度が固定されている真空槽というセットアップと比較して，微量な反跳イオンをより少ない損失で質量分析エリアに導入することが可能になる． さらに，異性体分離をするために導入予定であった，イオンファネルと移動管質量分析器の組み合わせによる分析システムの有効性の検討を行った．その結果，有限なリソースの中で幅広い種類の異性体の分離を行うには移動管法は適していない可能性があることが分かった．よって，異性体分離法の代替案として，イオントラップとレーザーを用いた冷イオン振動前期解離分光法を採用することとし，最適なイオントラップ形状決定のため，線径トラップ型イオントラップのイオン軌道シミュレーションを開始した．
• Elucidation of ion-surface reactions on a interstellar dust surface: exploring their unknown roles in molecular evolution

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2018/04 -2021/03 

  Author : Nakai Yoichi

   

  We have performed experimental studies of the reactions between low-energy molecular ions and the surface of interstellar dust ice, for which there was little experimental information. For this purpose, we have developed an experimental apparatus using a reactive scattered ion mass spectrometry (RIS), which is more sensitive than the conventional detection methods for chemical species existing on the surface. The method was improved so that the advantage of RIS could be utilized for chemical species on the low-temperature ice surface. As a result, we have achieved high detection sensitivity for chemical species on low-temperature ice surface. The reaction products were observed after irradiating the surface of the ice thin film formed on the cooled metal substrate with low-energy CH3+ ions. We obtained experimental results indicating the formation of methanol molecules due to the irradiation of the CH3+ ions to the ice surface.
• 分子雲における氷・有機物生成

  文部科学省: 科学研究補助金(新学術領域研究(研究領域提案型))

  Date (from‐to) : 2013/06 -2018/03 

  Author : 香内 晃
• 星間塵表面での分子進化と新しい同位体分別機構

  文部科学省: 科学研究補助金(基盤研究(S))

  Date (from‐to) : 2012/05 -2017/03 

  Author : 渡部 直樹
• Quantitative investigation for ion-induced nucleation under non-equilibrium conditions of association/dissociation reactions: experimental approaches for elementary formation processes

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2013/04 -2016/03 

  Author : NAKAI Yoichi, WATANABE Naoki, KOJIMA Takao, HIDAKA Hiroshi

   

  We performed stable and precise measurements compared with previous studies for Gibbs free energy changes of stepwise association reactions of a water molecule to H3O+(H2O)n ions using a ion drift tube with a selected ion injection. Furthermore, an empirical effective temperature of the reaction equilibrium constants was obtained for association/dissociation reactions of a water molecule to/from H3O+(H2O)n ions in a pure water vapor. The effective temperature means a representative physical quantity of collision energy influenced by an electric field. It was found that a new parameter describing electric field dependence of the effective temperature presumably reflects structures of H3O+(H2O)n ions. We also performed R&D of ion handling methods in an RF ion trap, such as an ion mass selection, in order to make use of RF ion traps for cluster formation experiments.
• 極低温原子間力顕微鏡によるアモルファス氷の表面構造および表面電位の解明

  文部科学省: 科学研究補助金(基盤研究(C))

  Date (from‐to) : 2014/05 -2016/03 

  Author : 日髙 宏
• 氷生成過程のその場観察・構造解析のための極低温超高真空透過型電子顕微鏡の開発

  文部科学省: 科学研究補助金(基盤研究(A))

  Date (from‐to) : 2013/10 -2016/03 

  Author : 香内 晃
• Quantitative elucidation for ion induced nucleation in the atmosphere: Approach through the experiments for elementary processes

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2010/04 -2013/03 

  Author : NAKAI Yoichi, WATANABE Naoki, KOJIMA Takao, HIDAKA Hiroshi

   

  Experimental study for cluster ion formation, early stages of ion induced nucleation, has been performed. We developed the experimental equipment, in which the region for production of initial ions is separated from that for generation of cluster ions, in order to define the reaction paths. Gibbs free energy changes for the stepwise association of an H2O molecule were measured for H3O+(H2O)n cluster ions and our method has provided more stable and precise results compared with previous measurements. In the use of initial NO+ ions, we have reduced influence of metastable NO+ ions in produced initial ions, using hydrogen buffer gas.
• Elucidation of the mechanism of deuterium enrichment for ammonia molecule on the interstellar grain surface and use the enrichment fraction for temperature estimation of molecular clouds

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2012 -2012 

  Author : HIDAKA Hiroshi

   

  ECR (Electron Cyclotron Resonance) nitrogen atomic source using microwave frequency 2.45GHz has been developed for use in the experimental study of the ortho-para ratio and the degree of deuterium enrichment of ammonia molecule which formed on the interstellar grain surface by the atom-atom addition reactions in molecular clouds. Magnetic field configuration for the plasma confinement was designed by 3D magnetostatic analysis, in order to achieve the nitrogen atomic source with the high flux and the high dissociation fraction.
• Observation of surface structure of amorphous ice and role of amorphous ice in surface atomic reactions at low temperatures

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2010 -2012 

  Author : KOUCHI Akira, WATANABE Naoki, HIDAKA Hiroshi

   

  An ultrahigh vacuum low temperature atomic force microscope for in-situ deposition of amorphous ice and for observation of ice surface has been developed. We have succeeded to observe the surface structure of amorphous ice and found that the surface of amorphous ice is very porous. This might cause the catalytic properties of amorphous ice in surface atomic reactions.
• Ice surface processes: tunneling reactions and isotope fractionation

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2009 -2011 

  Author : WATANABE Naoki, HIDAKA Hiroshi

   

  Ice surface reactions relevant to chemical evolution and deuterium fractionation were experimentally investigated. Activation energies for ice-surface diffusion of H and D atoms were determined. It was found that effective mass of reaction system is a control-factor of tunneling reactions. The reactivities of tunneling reactions related to deuterium fraction of formaldehyde can be well explained by the effective masses. A novel route of CO_2 formation on the ice surface was found.
• Deuterium fractionation of water molecule via grain surface reactions at very low temperatures

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2009 -2011 

  Author : WATANABE Naoki, HIDAKA Hiroshi

   

  Water molecule formation and its deuterium fractionation via surface tunneling reactions were investigated experimentally, relevant to chemical evolution in a molecular cloud. We found that H_2O molecule is produced by tunneling reaction, OH + H_2, at very low temperature surfaces and that, from the isotope effect on the above reaction, the formation of OD is essential for deuterium fractionation of water rather than HD or D_2 formation.
• Study for the energy partition process in H2 formation by the H-H recombination on interstellar grain surface

  Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(若手研究(B))

  Date (from‐to) : 2007 -2008 

  Author : Hiroshi HIDAKA

   

  極低温星間塵表面上で生成・脱離した水素分子の反応熱分配過程を実験的に明らかにするため,低温基板表面で水素原子の結合反応により水素分子を生成し,脱離した水素分子の運動・振動・回転エネルギー分布を測定する実験装置を構築した.
• Role of cosmic-grain surface reactions in the deuterium fractionationof interstellar molecules

  Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(B))

  Date (from‐to) : 2007 -2008 

  Author : Naoki WATANABE, HIROSHI HIDAKA

   

  星間分子の重水素濃集プロセスとして研究代表者らが提唱している極低温星間塵表面反応を, 実験により定量的に評価した. 特に, 高度な重水素濃集が観測で確認されているホルムアルデヒド, メタノールの重水素化表面反応に焦点をあて, 重要な反応経路について実効的な反応速度定数を決定し, 上記分子種に関する重水素濃集の星間塵表面反応ネットワークを完成させた.