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用一种操作简单、反应条件温和的方法制备了分散性好的超微小Zn O@Si O2核壳量子点透明溶液,利用透射电子显微镜(TEM)、紫外吸收光谱(UV)、荧光光谱(FL)、纳米粒度和ZETA电位分析仪等技术对所制备纳米粒子的粒径大小、吸收光谱、发光性质进行表征。结果表明,Zn O@Si O2核壳量子点平均粒径在3~5 nm,在紫外灯下发出黄绿色荧光,紫外最大吸收在330 nm左右,可以发射出510 nm的荧光。同时,系统地考察了p H值、温度、不同金属阳离子以及不同阴离子对量子点荧光强度的影响。实验结果表明:当p H≤7时,量子点荧光完全猝灭;当p H>7时,量子点荧光强度随着p H值的增加而增强,当p H为9.0时,荧光强度达到最大,然后随着p H值的升高荧光略有降低。量子点随着温度的升高荧光强度逐渐降低,当温度达到50℃以上荧光完全猝灭。一价金属离子对量子点荧光强度基本没有影响,二价金属离子对量子点荧光削弱程度的大小顺序为Fe2+>Mn2+>Cu2+>Pb2+>Co2+>Ba2+>Mg2+,三价金属离子对量子点荧光削弱程度的大小顺序为Fe3+>Cr3+>Bi3+>Al3+。其中,Fe3+、Fe2+、Bi3+、Cr3+、Mn2+等金属离子对量子点的荧光有猝灭作用,PO43-、HPO42-、H2PO4-等离子对量子点荧光稍有增加作用,HCO3-、CO32-、CH3COO-、SO32-等阴离子对量子点的荧光有削弱甚至猝灭的作用,Cl-、SO42-、NO3-等离子对量子点荧光几乎没有影响。
The ultra-fine Zn O @ Si O2 core-shell quantum dot transparent solution with good dispersibility was prepared by a simple and mild reaction condition. The structure of the quantum dots was characterized by transmission electron microscopy (TEM), ultraviolet absorption spectroscopy (UV) FL), nano-particle size and ZETA potential analyzer technology to characterize the particle size, absorption spectra, luminescent properties of the prepared nanoparticles. The results show that the average particle diameter of Zn O @ Si O2 core-shell quantum dots is in the range of 3 to 5 nm, emitting yellow-green fluorescence under ultraviolet light and the maximum UV absorption is about 330 nm, which can emit 510 nm fluorescence. At the same time, the effect of p H value, temperature, different metal cations and different anions on fluorescence intensity of quantum dots was systematically investigated. The experimental results show that the quantum dot fluorescence quenches completely when p H is less than 7. When p H> 7, the fluorescence intensity of the quantum dot enhances with the increase of p H value. When p H is 9.0, the fluorescence intensity reaches the maximum , Then the fluorescence decreases slightly with increasing p H value. The quantum dot fluorescence intensity decreases with increasing temperature, and the fluorescence quenches completely when the temperature reaches 50 ℃. The monovalent metal ions have no effect on the fluorescence intensity of quantum dots, and the order of the weakening of quantum dots by divalent metal ions is Fe2 +> Mn2 +> Cu2 +> Pb2 +> Co2 +> Ba2 +> Mg2 +. The trivalent metal ions weaken the fluorescence of quantum dots The order of magnitude is Fe3 +> Cr3 +> Bi3 +> Al3 +. Among them, metal ions such as Fe3 +, Fe2 +, Bi3 +, Cr3 +, and Mn2 + quenched the fluorescence of quantum dots. PO43-, HPO42- and H2PO4- ions slightly increased quantum dot fluorescence. HCO3-, CO32- and CH3COO- , SO32- and other anions have the effect of weakening or even quenching the fluorescence of the quantum dots. Cl-, SO42- and NO3- ions have almost no effect on the quantum dot fluorescence.