Electron spin resonance studies on radiolysis of crystalline methanol at 4.2 K
Electron spin resonance studies on radiolysis of crystalline methanol at 4.2 K
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4.2 K 下结晶甲醇辐射分解的电子自旋共振研究
DOI：
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发表时间：
1979
期刊：
影响因子：
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通讯作者：
M. Iwasaki
中科院分区：
文献类型：
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作者：
K. Toriyama;M. Iwasaki
用电子自旋共振谱研究了4.2 K时结晶甲醇的辐解反应及其产生的自由基结构。首次观察到在4.2K辐照纯CH/sub 3/OH时，除了常规的CH/sub 2/OH外，还生成了CH/sub 3/O和CH/sub 3/O作为主要产物。得到了CH/sub 3/O和CH/sub 3/在77 K以下均转化为CH/sub 2/OH的直接证据。CH/sub 3/O转化为CH/sub 2/OH的过程中存在分子内氢原子转移。除了这些孤立的自由基外，还形成了大量的CH/sub 3/和CH/sub 2/OH之间的自由基对。在低于77 K时，该对中的CH/sub 3/也转化为CH/sub 2/OH，在CH/sub 2/OH之间形成自由基对。自由基对分离的变化表明CH/sub 3/从相邻的CH/sub 3/基团中夺取一个氢原子，形成CH/sub 2/OH。有人建议，自由基对形成的电子和阳离子物种的重组。(The讨论了CH/sub 3/O的电子结构和几何结构。自由基是以氧为中心的。pi..自由基和CH/sub 3/基团在4.2K发生隧穿转动。根据A线和E线的更多分裂，在cos/sup 2/ theta规则中的B/sub 0/和B/sub 2/ beta..质子耦合在氧中心.. pi..据估计，自由基分别为5和94 G。9张图，3张表。«少
Radiolysis of crystalline methanol and the structure of radicals produced have been studied at 4.2 K using electron spin resonance spectroscopy. It has been observed for the first time that CH/sub 3/O and CH/sub 3/ are formed as major products together with conventional CH/sub 2/OH in pure CH/sub 3/OH irradiated at 4.2 K. The direct evidence was obtained that both CH/sub 3/O and CH/sub 3/ convert into CH/sub 2/OH below 77 K. Intramolecular hydrogen atom transfer is suggested for the conversion from CH/sub 3/O into CH/sub 2/OH. Besides these isolated radicals, considerable amounts of radical pairs between CH/sub 3/ and CH/sub 2/OH were formed. CH/sub 3/ in this pair also converts into CH/sub 2/OH forming radical pairs between CH/sub 2/OH below 77 K. The change in the radical pair separation indicates that CH/sub 3/ abstracts a hydrogen atom from the neighboring CH/sub 3/ group forming CH/sub 2/OH. It is suggested that the radical pairs are formed from recombination of an electron and a cationic species. (The electronic and geometrical structure of CH/sub 3/O has also been discussed.) The radical is the oxygen-centered ..pi.. radical and the CH/sub 3/ group undergoes tunneling rotation at 4.2 K. From the A- and E-linemore » splittings, B/sub 0/ and B/sub 2/ in the cos/sup 2/ theta rule for the ..beta.. proton coupling in the oxygen-centered ..pi.. radicals have been estimated to be 5 and 94 G, respectively. 9 figures, 3 tables.« less