碘掺杂聚对苯撑的EPR和σ_(dc)  

EPR SPECTRUM AND σdc OF IODINE-DOPED PPP

作　　者：王刘坤 金长清 王敬伯[1] 

机构地区：[1]中国科学院长春物理研究所

出　　处：《发光学报》1990年第4期327-334,共8页Chinese Journal of Luminescence

基　　金：国家自然科学基金资助课题;863高技术资助课题

摘　　要：本文对聚对苯撑及其掺碘的样品进行了电子顺磁共振和直流电导率的研究,并分别给出了σdc和EPR谱室温线宽ΔHpp对碘浓度N(I)的变化关系。由于掺杂而诱导的单极化子和双极化子态之间产生极化子跃迁,利用这种跃迁过程解释了此材料的导电性质。从电子顺磁共振的实验结果发现,电子顺磁共振信号与掺碘浓度呈现一种新的现象。试图探讨未掺杂及掺杂的聚对苯撑材料中自旋产生的原因。我们提出了在掺碘后的聚对苯撑材料中,由于碘在材料中以不同形式存在,影响单极化子和双极化子的形成,导致单极化子态和双极化子态之间相互转化的概念。We have investigated the properties of electron paramagnetic resonance(EPR) spectra and de electrical conductivity (odc) from undoped and iodine-doped PPP prepared by Kovacic method. The experimental results of odc and EPR in iodine-doped PPP are presented here. It is found that a novel phenomenon occurs for EPR signals with the change of iodine concentration [N(I)] in doped PPP. According to our experimental results, it is suggested that polarons and bipolarons should change into each other in the iodine-doped PPP.In low-conducting PPP, the conductivity is described as interpolaron transfering processes among the polaron and bipolaron states induced by the doping. Because spin-charged polarons or spinless bipolarons, in the case of doped PPP, can be formed in the PPP chains due to doping,the , results show that odc rises with the increase of N(I) (see Fig.1).In the case of undopcd PPP, EPR signals were obviously observed. It is due mainly to the macrocycle defects which were created during preparation procedure,i. e. due to polynuclear aromatic eletron which is deiocalized on a few carbon atoms leading to an EPR spectra with nonhyperfine structure. In the case of iodine-doped PPP, a change of room-temperature EPR linewidth,Hpp,with different N(I) values is shown in Fig.4.Iodine used as dopant in PPP is a relatively weak eletron acceptor so that iodine molecule can have partly charge transfer with PPP chains. Furthermore, iodine may exist in different forms of I2,I-,I3- and I5-. The different electric fields formed respectively in iodine-doped PPP, have a different influence on the polarons and bipolarons in the chains so that relative content of polarons or bipolarons in the PPP chains with the increase of N(I) may change. So Hpp varies in a novel way with the increase of N(I)(see Fig.4). The reactions are shown in equations 4-10.Further investigation is needed to confirm whether iodine exists in the forms of I2, I-, I3- and I3- or not. Content of iodine doped in PPP and Nspiu values are not given quantitatively

关 键 词：聚对苯撑 掺杂 碘 EPR σde 

分 类 号：O632.7[理学—高分子化学]