不同气氛下多孔硅中电子偶素湮没行为研究  

Study of annihilation behavior of positronium in porous silicon in different atmospheres

作　　者：李卓昕[1,2] 王丹妮[2] 王宝义[2] 薛德胜[1] 魏龙[2] 秦秀波[2] 

机构地区：[1]兰州大学磁学与磁性材料教育部重点实验室,兰州730000 [2]中国科学院高能物理研究所,核分析技术重点实验室,北京100049

出　　处：《物理学报》2010年第9期6647-6652,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10835006;10705031;60606011)资助的课题~~

摘　　要：使用正电子湮没谱学方法,在不同气氛下对电化学腐蚀法制备的多孔硅中电子偶素的湮没行为进行了系统的研究.正电子湮没寿命谱测试结果表明,样品中存在长达40ns的电子偶素湮没成分,并且进入多孔硅膜层的正电子约有80%形成电子偶素,具有非常高的电子偶素产额;在氧气气氛下,由于气体导致o-Ps发生自旋转化猝灭是使多孔硅样品中电子偶素寿命缩短的主要原因.结合正电子寿命-动量关联谱测量结果,分析了不同气氛下多孔硅样品中电子偶素湮没寿命及动量变化关系,讨论了多孔硅中电子偶素的湮没机理以及气氛对孔径计算理论模型的影响.Porous silicon （PS） prepared by electrochemical etching method has been studied by positron annihilation lifetime spectroscopy （PALS） and age-momentum correlation （AMOC） measurement in different atmospheres. The longest lifetime component in PALS results is ascribed to the annihilation of positronium in cavities of PS sample. It is found that 80% of the positrons implanted in PS film have formed positronium atoms. PALS results show that the lifetime of ortho-positronium has smaller value when the sample was in oxygen gas medium compared with those in other medium. AMOC results reveal that S parameter of three lifetime components in oxygen are all bigger than that in nitrogen atmosphere. These are probably caused by the oxygen leading to the spin-conversion of positronium atoms.

关 键 词：电子偶素 正电子湮没谱学方法 多孔硅 

分 类 号：O572.322[理学—粒子物理与原子核物理]