Photochemical Properties of Size-quantized Semiconductor Microcrystals and Their Applications

本论文研究了尺寸量子化半导体微晶的光化学性质及其潜在的应用。主要研究成果如下：1.聚环氧乙烷中量子化CdS的荧光性质。在聚氧化乙烯（PEO）薄膜中制备的量子化CdS微晶显示出强烈的橙子荧光。通过电解法将Ni^<2+>离子引入到PEO薄膜中，提高了CdS的荧光强度。2.量子化InAs和GaAs微晶的制备及其光学非线性。用金属有机法合成了量子化的InAs和GaAs微晶。这些微晶的粒径范围从1到8 nm，和大的尺寸量子化效应被证实。实验还表明，量子化的InAs和GaAs微晶在Nd：YAG激光的二次谐波辐照下，表现出很大的光学非线性. ...更多信息 大小分离的CdS微晶上的nsfer。甲基紫精的还原率与使用凝胶电泳分级制备的CdS微晶的颗粒尺寸减小而增加。观察到的结果成功地分析了由于尺寸量子化导致的导带边的位移。4.对羟基苯硫酚修饰PbS微晶的表面结构及其对光生电荷转移的影响。采用[Pb^2+]/[S^<2->] = 1.2和3.0两种不同的浓度比和固定的[ArSH]/[Pb^2+] = 4.0的浓度比制备了量化的、单分散的对羟基苯硫酚（ArSH）包覆的PbS微晶。在原子尺度上分析了ArSH封端的PbS微晶的表面结构，通过检查PbS颗粒的化学分析数据对两种表面结构模型（完全和部分被封端的ArSH占据的表面位置）的评估组合物的拟合。通过实验发现的颗粒团聚倾向和添加Pb^2+离子对甲基紫精在颗粒上的光诱导还原速率的影响的差异，使所提出的表面结构合理化。少

Photochemical properties and potential applications of size-quantized semiconductor microcrystals were investigated in the present research. Major achievements are as follows;1.Fluorescence properties of quantized CdS prepared in poly(ethylene oxide). Quantized-CdS microcrystals prepared in poly(ethylene oxide) (PEO) film exhibited a strong orange fluorescence. The fluorescence intensity of CdS incorporated in PEO film was increased by the introduction of Ni^<2+> ions into the film by electrolysis.2.Preparation and optical nonlinearity of quantized InAs and GaAs microcrystals. Quantized InAs and GaAs microcrystals were synthesized by organometallic methods. The particle size of these microcrystals ranged from 1 to 8 nm, and great size-quantization effects were confirmed. It was also demonstrated that quantized InAs and GaAs microcrystals exhibited a large optical nonlinearity when these colloids were irradiated with the second harmonics of Nd:YAG laser beams.3.Photoinduced electron tra … More nsfer on size-separated CdS microcrystals. The rate of reduction of methylviologen on CdS microcrystals prepared by fractionation with the use of gel electrophoresis increased with decreasing the particle size. The observed results were successfully analyzed in terms of shifts in the conduction bandedge due to the size-quantization.4.Surface structures of PbS microcrystals modified with 4-hydroxythiophenol and their influences on photoinduced charge transfer. Quantized and monodispersed PbS microcrystals capped with 4-hydroxythiophenol(ArSH) were prepared using two different concentration ratios of [Pb^<2+>]/[S^<2->] = 1.2 and 3.0 with fixed concentration ratio of [ArSH]/[Pb^<2+>] = 4.0. The surface structures of ArSH-capped PbS microcrystals were analyzed in atomic scale by examining the fitness of the chemical analyses data of the PbS particles to the evaluated compositions for two kinds of surface structure models (fully and partially occupied surface sites with the capped ArSH). The proposed surface structures were rationalized by experimentally found differences both in agglomeration tendencies of the particles and in the effect of the addition of Pb^<2+> ions on the rate of photoinduced reduction of methylviologen on the particles. Less