2021 Fiscal Year Final Research Report
Novel method for radical reaction rate measurement utilizing electron spin polarization and spin coherence
Project/Area Number |
19K05376
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Research Category |
Grant-in-Aid for Scientific Research (C)
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Allocation Type | Multi-year Fund |
Section | 一般 |
Review Section |
Basic Section 32010:Fundamental physical chemistry-related
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Research Institution | Kanagawa University |
Principal Investigator |
Kawai Akio 神奈川大学, 理学部, 教授 (50262259)
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Project Period (FY) |
2019-04-01 – 2022-03-31
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Keywords | ラジカル反応 / パルスESR / 時間分解ESR / スピン分極 / 反応速度定数 |
Outline of Final Research Achievements |
This study aims to develop novel and advanced methods to determine reaction rate constants of free radicals in liquid phase. In the beginning, a photolysis of an oxim ester compound was investigated to find better reaction systems, which enables us to measure spin polarized radicals with high ESR sensitivity. Then, the spin-echo detection method utilizing the pulsed ESR was examined in the reaction systems of radicals and fullerens. The radical scavenging of the fullerenes were found to be diffusion-controlled. Spin-echo method was also applied to the reaction systems of the radicals generated by oxim ester compound. In addition, a novel procedure for rate constant measurements was developed by monitoring free induction decay (FID) of the reacting radicals. FID method was effective to the radicals which show weak spin echo such as benzyl and dehydrogenated dioxane radicals. The two methods were argued in the view points of radical selectivity and experimental difficulties.
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Free Research Field |
物理化学
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Academic Significance and Societal Importance of the Research Achievements |
ラジカルは、反応活性の高い化学種であり、活性酸素反応や光重合、高分子のグラフトなど、人類の活動に大きく関わっている。従ってラジカル反応の速度定数を正確に知ることが重要である。しかしながら、ラジカルは短寿命であるため、網羅的に観測対象とできる時間分解計測手法がなかった。本研究は、この状況を打開すべく、ラジカルのスピン分極を利用する測定感度の改良、およびパルスESRを用いたラジカルのスピンコヒーレンス生成を利用した独創的な速度定数決定法の開拓を行った。これにより、具体的にはラジカル消去剤として知られて様々な製品に用いられているフラーレンに対し、正確なラジカル消去速度定数を決定することができた。
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