Elucidation of nuclear-spin conversion mechanism of water molecules by terahertz and infrared spectroscopy
| Project/Area Number |
18K14182
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 32010:Fundamental physical chemistry-related
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| Research Institution | Japan Atomic Energy Agency (2019)
Gakushuin University (2018) |
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Principal Investigator |
Yamakawa Koichiro 国立研究開発法人日本原子力研究開発機構, 原子力科学研究部門 原子力科学研究所 先端基礎研究センター, 研究職 (60633279)
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| Project Period (FY) |
2018-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2019: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2018: ¥3,380,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥780,000)
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| Keywords | 核スピン転換 / 水クラスター / テラヘルツ吸収分光 / 赤外吸収分光 / 第一原理計算 / テラヘルツ分光 / 赤外分光 |
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| Outline of Final Research Achievements |
The nuclear-spin conversion rates of light and heavy water molecules trapped in rare-gas solids were measured with infrared absorption spectroscopy. The temperature dependence of the conversion rates was shown to be well-reproduced by the conversion model for molecular monomers devised by the representative. This result assures the validity of this model. With regard to water clusters, the representative specified the intermolecular fundamentals of the dimer, trimer, and tetramer by using terahertz and infrared absorption spectroscopy covering the wide wavenumber range of 60-7000 cm-1 as well as the ab-initio-computational way newly developed. Based on these accomplishments, the nuclear spin conversion in the water dimer was detected for the first time. The conversion rates of hydrogen and methane molecules were also determined, which will enable the study of the nuclear spin conversion in hetero-clusters.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究で検証した「核スピン転換モデル」は，水以外の分子にも適用可能である．このモデルを用いることで，天体の熱履歴の解明，核スピン異性体の存在比の制御が可能になる．さらに本研究では，「メタン分子の3種異性体間の転換」，「マトリックス中の水素分子の転換」を世界で初めて観測しており，この点からも「単量体の転換研究」を大きく発展させたと言える．
本研究により確定した，水クラスターの2，3，4量体によるテラヘルツ吸収の帰属は，大気中における水蒸気の温室効果の評価に不可欠である．また，理論的に予測されていた「クラスター中の核スピン転換」を初めて観測したことは，今後この分野の研究を発展する際の礎となる．
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Report
(3 results)
Research Products
(28 results)
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[Presentation] Far- and mid-infrared spectroscopy of matrix-isolated clusters and matrix-sublimated ice of D2O2018
Author(s)
Nasu, H., Niwata, K., Azuma, Y., Tanaka, T., Arakawa, I., Yamakawa, K.
Organizer
25th International Conference on High Resolution Molecular Spectroscopy
Related Report
Int'l Joint Research
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