Quantum confinement effects in luminescence of rare earth (III) ions - doped semiconductor nanocrystals

近年来，量子限制效应已在各种超导纳米晶体中得到证实。研究了掺杂稀土离子的CdS和ZnS纳米粒子嵌入溶胶-凝胶SiO_2玻璃和SiO_2纳米管MCM 41多孔基质中的发光的基质依赖性。通过TEM光谱直接观察到直径为10 nm的颗粒。稀土离子及其配合物掺杂的溶胶-凝胶玻璃在热退火条件下表现出晶场分裂的特征。SiO_2干凝胶和溶胶-凝胶玻璃中Eu^<3+>与稀土（III）离子之间的能量传递受到陷阱限制的能量传递过程的限制。CPL光谱被发现是相当有用的分析一些光学活性金属配合物在主体中的手旋光结构。在不同条件下制备了（Zn，Cd）S：RE（III）（RE=Tb^<3+>，Eu^<3+>等）镶嵌在SiO_2和MCM 41中的纳米粒子，测量了它们的时间分辨发光光谱、寿命及其温度依赖性。与体相晶体的红光发射相比，SiO_2：CdS玻璃中由于表面缺陷引起的黄带发光占主导地位。MCM 41/CdS：Eu^<3+>中的纳米颗粒代表皮秒寿命的存在，小颗粒中亚ms寿命成分的缩短，以及0-2跃迁的光谱蓝移。利用Z扫描方法和飞秒激光光谱系统研究了CdS/ZnS掺杂ZrO_2薄膜的量子限域效应，发现CdS/ZnS掺杂ZrO_2薄膜具有较强的非线性优化效应。

Recently quantum confinement effect has been known in various semiconductor-nanocrystals. Host dependence is investigated in luminescence of CdS and ZnS nanoparticles doped with rare earth (III) ions embedded in the porous hosts of sol-gel SiO_2 glasses and silica nanotubes MCM41. Particles of 10nm in diameter are directly observed by TEM spectroscopy. Rare earth (III) ions and complexes - doped sol-gel glasses show crystal field splitting characteristics of thermal annealing conditions. Energy transfer between Eu^<3+> and rare earth (III) ions is restricted by trap -limited energy transfer processes in SiO_2 xerogel and sol-gel glasses. CPL spectra are found to be quite useful to analyze the chiroptical structures of some optical active metal complexes in the hosts. Nanoparticles of (Zn, Cd) S:RE(III) (RE=Tb^<3+>,Eu^<3+> etc) embedded in SiO_2 and MCM41 are prepared in various conditions to measure time resolved luminescence spectra, lifetimes and their temperature dependence. In comparison to red emission of bulk crystals, yellow band luminescence due to surface defects is dominant in SiO_2:CdS glasses. Nanoparticles in MCM41/CdS:Eu^<3+> represent the presence of pico-seconds lifetime, shortening of sub-ms lifetime components in small particles, and spectral blue shifts of 0-2 transitions. Strong non-linear optimal effects due to quantum confinement effect are also found in CdS/ZnS doped-ZrO_2 thin films using Z-scan method and femto-second laser spectroscopy system.