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Exploration into the Possibility of the Molecular Hydrogen Formation Mediated by Polyatomic Molecules in Interstellar Space

Research Project

Project/Area Number 11640502
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Physical chemistry
Research InstitutionShizuoka University

Principal Investigator

AIHARA Jun-ichi  Shizuoka University, Faculty of Science, Professor, 理学部, 教授 (40001838)

Project Period (FY) 1999 – 2001
Project Status Completed (Fiscal Year 2001)
Budget Amount *help
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2001: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1999: ¥1,700,000 (Direct Cost: ¥1,700,000)
Keywordsinterstellar molecule / polycyclic aromatic hydrocarbon / PAH / PAH cation / catalyst / molecular hydrogen formation / reaction mechanism / density functional theory / ab initio分子軌道計算 / アントラセン / ピレン / 芳香族性 / フラーレン
Research Abstract

In interstellar space hydrogen exists mainly as hydrogen atoms. A protion of hydroegn also exists as hydrogen molecules. However, the H_2 formation mechanism in space remains quite elusive. According to the popular hypothesis, H_2 is generated on the surface of interstellar grains. However, kinetic aspects of the H_2 formation cannot be explained by this hypothesis. We investigated the possibility of the H_2 formation mediated by polycyclic aromatic hydrocarbon (PAH) radical canons using ab initio molecular orbital (PMP2/6-31G**) and density functional (B3LYP/6-31 G**) theories
We presumed that H_2 is formed via two consecutive reactions. First, a hydrogen atom is added to the PAH^+ cation. Next, a second hydrogen atom approaches and abstarcts one of the methylene hydrogens in the arenium ion to form a hydrogen molecule. PAHs employed were naphthalene, anthracene, pyrene, and coronene. No activation energy is needed for the first reaction. The second reaction was found to require a small activation energy of 0-3 kcal/mol. Therefore, such a pair of reactions can be considered one of the plausible H_2 formation mechanisms in cold space. These reactions might also be effective for enriching deuterium in the PAH molecules
In fact, it is not easy to estimate an accurate activation energy for a hydrogen-transfer reaction because density functional theory overestimates correlation energy for a loosely bound complex. The MP2 procedure overestimates the correlation energy. We then evaluated the activation energy for the second reaction using PMP2/6-31 G** and B3LYP/6-31G**//PMP2/6-31G** and averaged the two values to obtain the reasonable activation energy

Report

(4 results)
  • 2001 Annual Research Report   Final Research Report Summary
  • 2000 Annual Research Report
  • 1999 Annual Research Report
  • Research Products

    (20 results)

All Other

All Publications (20 results)

  • [Publications] Jun-ichi Aihara: "Why Are Some Polycyclic Aromatic Hydrocarbons Extremely Reactive?"Physical Chemistry Chemical Physics. 1. 3193-3197 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Jun-ichi Aihara: "Reduced HOMO-LUMO Gap As an Index of Kinetic Stability for Polycyclic Aromatic Hydrocarbons"Journal of Physical Chemistry A. 103. 7487-7495 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Jun-ichi Aihara: "There Are No Antiaromatic Molecules in Interstellar Space"Internet Electronic Journal of Molecular Design. 1. 52-58 (2001)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Jun-ichi Aihara: "Nucleus-Independent Chemical Shifts and Local Aromaticities in Large Polycyclic Aromatic Hydrocarbons."Chemical Physics Letters. 365. 34-39 (2002)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Mutsumi Hirama: "Possible Molecular Hydrogen Formation Mediated by the Radical Cations of Anthracene and Pyrene"Journal of Computational Chemistry. 24. 1378-1382 (2003)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Jun-ichi Aihara: "Magnetic Resonance Energy and Aromaticity of Polycyclic Aromatic Hydrocarbon Dianions/Dications (BCSJ賞受賞論文)"Bulletin of the Chemical Society of Japan. 77. 651-659 (2004)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Jun-ichi Aihara: "Why Are Some Polycyclic Aromatic Hydrocarbons Extremely Reactive?"Physical Chemistry Chemical Physics. 1(14). 3193-3197 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Jun-ichi Aihara: "Reduced HOMO-LUMO Gap As an Index of Kinetic Stability for Polycyclic Aromatic Hydrocarbons"Journal of Physical Chemistry A. 103(37). 7487-7495 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Jun-ichi Aihara, Mutsumi Hirama: "There Are No Antiaromatic Molecules in Interstellar Space"Internet Electronic Journal of Molecular Design. 1(1). 52-58 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Jun-ichi Aihara: "Nucleus-Independent Chemical Shifts and Local Aromaticities in Large Polycyclic Aromatic Hydrocarbons"Chemical Physics Letters. 365(1). 34-39 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Mutsumi Hirama, Toshimasa Ishida, Jun-ichi Aihara: "Possible Molecular Hydrogen Formation Mediated by the Radical Cations of Anthracene and Pyrene"Journal of Computational Chemistry. 24(12). 1378-1382 (2003)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Jun-ichi Aihara: "Magnetic Resonance Energy and Aromaticity of Polycyclic Aromatic Hydrocarbon Dianions/Dications. Note : This paper won the BCSJ Award"Bulletin of the Chemical Society of Japan. 77(4). 651-659 (2004)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] J.Aihara: "Kinetic Stability of Metallofullerenes as Predicted by the Bond Resonance Energy Model"Physical Chemistry Chemical Physics. 3・8. 1427-1431 (2001)

    • Related Report
      2001 Annual Research Report
  • [Publications] K.Fujine, T.Ishida, J.Aihara: "Localization Energies for Graphite and Fullerenes"Physical Chemistry Chemical Physics. 3・18. 3917-3919 (2001)

    • Related Report
      2001 Annual Research Report
  • [Publications] J.Aihara: "Kinetic Stability of Carbon Cages in Non-classical Metallofullerenes"Chemical Physics Letters. 343・5-6. 465-469 (2001)

    • Related Report
      2001 Annual Research Report
  • [Publications] J.Aihara, M.Hirama: "There Are No Antiaromatic Molecules in Interstellar Space"Internet Electronic Journal of Molecular Design. 1・1. 52-58 (2002)

    • Related Report
      2001 Annual Research Report
  • [Publications] Jun-ichi Aihara: "Correlation Found between the HOMO-LUMO Gap and the Reactivity for Isolated-Pentagon Isomers of Fullerenes."Physical Chemistry Chemical Physics. 2・14. 3121-3125 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] Jun-ichi Aihara: "Reduced HOMO-LUMO Gap as an Index of Kinetic Stability for Polycyclic Aromatic Hydrocarbons"Journal of Physical Chemistry A. 103・37. 7487-7495 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] Jun-lchi Aihara: "Why Are Some Polycyclic Aromatic Hydrocarbons Extremely Reactive?"Physical Chemistry Chemical Physics. 1・14. 3193-3197 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] 相原惇一: "宇宙空間をただようフラーレン"季刊化学総説. 43・1. 245-245 (1999)

    • Related Report
      1999 Annual Research Report

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Published: 1999-04-01   Modified: 2016-04-21  

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