γ射线辐射诱导聚碳硅烷自由基的衰变  

Decay of Free Radicals in Polycarbosilane Induced by γ-Rays Irradiation

作　　者：程勇[1,2] 李小虎[1,2] 刘伟华[2] 吴国忠[2] 王谋华[2] 

机构地区：[1]上海大学理学院,上海200444 [2]中国科学院上海应用物理研究所,上海201800

出　　处：《高等学校化学学报》2016年第3期595-599,共5页Chemical Journal of Chinese Universities

基　　金：中国科学院战略性先导科技专项子课题(批准号:XDA02040300);国家自然科学基金(批准号:11575279);上海市自然科学基金(批准号:15ZR1448600)资助~~

摘　　要：利用电子自旋共振波谱(ESR)研究了在N2气中γ射线辐射诱导聚碳硅烷(PCS)自由基的产生和演变行为.ESR谱图分析结果表明,γ射线辐射诱导PCS产生的自由基为硅自由基(≡Si·).低剂量辐照时硅自由基的浓度随吸收剂量的增加而线性增加,硅自由基的辐射化学产额G值约为9,吸收剂量达到200 k Gy后,硅自由基的浓度趋于饱和.室温下硅自由基的浓度随存储时间的延长而逐渐降低,在N2气中存储时硅自由基的半衰期约23 d,在空气中存储时硅自由基的氧化反应导致衰减速率加快,半衰期仅为8 h.温度升高硅自由基衰减速率加快,在N2气中250℃加热处理可以完全清除硅自由基.The formation and decay behavior of the free radicals trapped in polycarbosilane（ PCS） induced byγ-rays irradiation in N2 were investigated by electron spin resonance（ ESR）. ESR analysis showed that the trapped radicals induced by γ-rays irradiation were assigned to Si radicals（ ≡Si·）. The concentration of free radicals increased with absorbed dose linearly at the lower dose,and the G value of the radical formation was calculated to be 9. However,the concentration of free radicals tends to be saturated when the absorbed dose reached 200 k Gy. Upon storage in N2 at ambient temperature the free radicals decayed slowly with a half-life of23 d. On the contrary,the free radicals decayed rapidly after the sample was exposed to air due to their oxidation,the half-life was only 8 h. The rate of radical decay was accelerated by annealing at elevated temperature,the free radicals trapped in PCS could be removed thoroughly after heating up to 250 ℃ in N2.

关 键 词：电子自旋共振 聚碳硅烷 γ射线辐射 自由基 

分 类 号：O631.34[理学—高分子化学] O613.72[理学—化学]