Preparation of Excited Electron System and Its Dynamics

这个研究项目包括三个研究。1.有机聚合物中PBI_2微晶的光学性质。研究了嵌入E-MAA共聚物的超薄PbI_2微晶在低温下的吸收光谱。从这些结果可以得出激子的平动运动是量子化的。发光测量结果表明，由于尺寸约束效应和周围聚合物的介电约束效应，激子的结合能变得非常大。此外，我们还测量了激子能量和共振拉曼散射作为层数的函数与水压的关系。这些结果阐明了PbI_2单、双、三层晶体的原子键转变为离子键。近年来，利用泵浦-探针实验研究了激子-表面和激子-声子相互作用，并利用磁光方法研究了激子波函数的收缩。2.NaCl晶体中CuCl微粒的光学性质。在激子带的尺寸选择性激发下，测量了发光衰减时间的尺寸依赖性。发现由于巨振子强度效应，激子超辐射在细粒子中发生。发光带宽度的温度依赖性表明激子在低温下被声子散射。3.沸石中PbI_2，HgI_2,BiI_3,Na，K，Rb簇的电子性质研究了载于沸石中的PbI_2、HgI_2、BiI_3、团簇的吸收光谱中激子能量和振子强度的量子尺寸效应。在高负载的PbI_2簇中，可以观察到簇序的反射率非常高。在含有Na，K，Rb的沸石中，由于簇的两能级之间的电子跃迁而出现吸收带，并且由于表面类似等离子体的形成而出现吸收带。特别是在中等浓度含K簇的沸石中，在3K左右观察到铁磁相。少

This research project consists of three studies. 1.Optical properties of PBI_2 microcrystals embedded in organic polymer.Absorption spectra of ultra thin PbI_2 microcrystals embedded into E-MAA copolymer have been measured at low temperatures. From these results it is concluded that the translational motion of the exciton is size quantized. From the luminescence measurements, it is suggested that the binding energy of the exciton becomes very large both for the size confinement effect and the dielectric confinement effect by the surrounding polymer. Moreover, we have measured the hydropressure dependence of the exciton energy and the resonant Raman scattering as a function of the layer number.these results clarify that the atomic bonding of the PbI_2 mono-,double-and triple-layer crystals changes to the ionic one. Recently, the exciton-surface and exciton phonon interactions are studied by the pump-probe experiments,and shrinkage of the exciton wave function by the magneto-optical meas … More urements. 2.Optical properties of CuCl fine particles embedded in NaCl crystal. Under the size selective excitation of the exciton band,the size dependence of the luminescence decay time has been measured. It is found that the exciton superradiance due to the giant oscillator strength effect is taken place in the fine particles. The temperature dependence of the luminescence band width suggests the exciton is scattered by acoustic phonons at low temperatures. 3.Electronic properties of PbI_2,HgI_2,BiI_3,Na,K,Rb Clusters in zeolite.Quantum size effects of the exciton energy and the oscillator strength have been observed in the absorption spectra of PbI_2,HgI_2,BiI_3,clusters loaded in zeolite. In highly loaded PbI_2 clusters,the extremely high reflectivity is observed for the ordering of the cluster. In the zeolite containing Na,K,Rb,there appear absorption bands due to electronic tgransition between two levels of the cluster and a band due to the surface plasmon like formation. Especially,ferromagnetic phase is observed at about 3K in the zeolite containing K clusters with medium concentration. Less