STUDY OF CHEMICAL REACTION MECHANISM OF INSIDE AND SURFACE OF SOLID BY ION-BEAM IRRADIALATION

我们从高密度电子激发和线性能量转移效应两个方面研究了高能离子束对基本聚合物的辐射效应。在离子束的作用下，聚合物中发生了断链、交联、碳化、烧蚀和溅射等化学反应。然而，这些反应的机制尚不清楚。为了了解离子束辐照聚硅烷薄膜在离子束辐照下的反应机理，我们报道了离子束辐照聚硅烷薄膜的时间依赖性发射光谱。例如，在2.0 MeV He+离子束辐照下，在室温下测量了聚甲基苯基硅烷（PMPS）和聚甲基丙基硅烷（PMPrS）的时间依赖性发射光谱。特别是在354K，313K和270K下获得了聚二正己基硅烷（PDHS）的发射光谱。在带隙跃迁中，PMPS、PMPrS、PDHS分别在355nm、350nm、385 nm和340nm左右发出荧光。此外，在所有温度下都观察到约440nm的辐射。这些光谱在离子束照射下发生了剧烈的变化。我们得出结论，440nm的发射是由于离子束引起的聚硅烷的缺陷和网络结构。

We have been studying radiation effects of high energy ion beams on fundamental polymers in the aspect of the hihg density electronic excitation and linear energy transfer (LET) effects. The chemical reactions in the polymers induced by ion beams are observed as chain scission, cross-linking, carbonization, ablation and sputtering. The mechanisms of these reactions, however, have not been cleared yet. We report on time-dependent emission spectra from ion-beam irradiated polysilane thin films in order to understand reaction mechanisms under the irradiation of ion beams For example, time-dependent emission spectra from poly (methylphenylsilane) (PMPS) and poly (methyl-propylsilane) (PMPrS) were measured at room temperature under irradiation of 2.0 MeV He+ion beams. Especially, emission spectra of poly (di-n-hexylsilane) (PDHS) were obtained at 354K,313K and 270K.Fluorescences around 355nm for PMPS,350nm for PMPrS,and 385 and 340nm for PDHS from band gap transitions were observed. Furthermore, emissions around 440nm were observed at all temperature examined. These spectra drastically changed under ion beam irradiation. We conclude that the 440nm emission is due to the defect and network structures of polysilanes induced by ion beams.