Selective Synthesis and Advanced Characteristic of CdSe Semiconductor Quantum Dots by Aqueous Phase

This work mainly investigated the influences of some factors, such as, synthesis methods, precursor alteraatives, and vacuum heat-treating process, etc, on the fluorescent characteristics of the semiconductor quantum dots synthesized by aqueous phase. The research results indicate that the fluorescent characteristic of water- solution sample prepared from Na2 SO3 precursor was sensitive to water bath heating time, and specially, its photohuninescence spectrum shows the unique phenomenon of double excitation and emission peaks. Meanwhile, the fluorescent characteristic of water- solution sample prepared from NaBH4 precursor is slightly influenced by water bath heating time, and the sugface of CdSe quantum dots could be passivated by the excessive amount of NaBH4 precursor, which results in the effective decrease of surface traps and great enhancement of quantum yield. Furthermore, the fluorescent emission peaks of samples could be sharpened by vacuum heat-treating process, with its spectral full width at half of maximum （FWHM） around 30- 40 run, so the emission peaks become redshifi, of which the intensity greatly increases.     

CdS:Co掺杂量子点的合成与表征

通过微波辐射技术,过度金属钴离子可以成功地掺杂到CdS量子点内部.由于钴离子占据了量子点的中心位置,随着辐射时间的增加,钴离子逐渐向外渗透扩散,伴随此过程,掺杂后的量子点的紫外吸收峰和荧光发射峰都相应地发生了红移.通过X射线衍射和高分辨投射电镜表征发现,掺杂后的晶体依然为立体闪锌矿结构,并且具有量子点的晶体特征;经过紫外吸收和荧光光谱表征发现,与CdS量子点相比,除了荧光光谱的发射峰范围扩宽了50 nm,荧光稳定性和化学稳定性得到了很大的提高.     

量子点特性及荧光标记应用

量子点是直径在1～100 ml的一类半导体纳米粒子.与传统的有机荧光标记物相比,具有独特的光谱特性和良好的光化学稳定性,是一种理想的荧光标记物.本文概述了量子点基本知识及特性、标记方法以及在生物材料荧光标记中的应用及发展前景.量子点在荧光分析领域将开辟一种新的方法,在分析领域的应用也将对生命科学研究产生重要的影响.     

水溶性CdTe/CdS量子点的制备及发光特性

采用水相合成法,以三种不同的稳定剂：巯基乙醇,巯基乙酸和巯基乙胺制备了CdTe/CdS核壳结构的量子点.研究了反应时间和稳定剂的种类对量子点荧光的光学特性的变化趋势的影响.结果表明,随着量子点晶体生长时间的增加,量子点的荧光峰向红移,荧光发射强度增加,半峰宽几乎保持不变.稳定剂的种类对量子点的荧光发射峰的波长有较大的影响.采用CdS对CdTe进行包裹,制备壳核结构的CdTe/CdS量子点.包裹后能增强水相制备过程中量子点在水相中的荧光强度和发光稳定性,改变量子点的荧光特性.采用红外光谱,对稳定剂和量子点之间的连接关系进行了初步探讨,并采用透射电子显微镜,对CdTe/CdS量子点的微观形态进行观察.     

Imaging Escherichia coli using streptavidin functionalized quantum dots as a Nano-fluorescent probe

It is extremely important for bacteria detection in many fields,such as medical diagnosis and food safety.In this paper,streptavidin functionalized quantum dots(SA-QDs),as a nano-fluorescent probe,were used to attach with Escherichia coli(E.coli) for the detection and identification of bacteria with immunoreactions and biotin-streptavidin affinity.Fluorescent images of the bacteria and the fluorescence intensity were used to evaluate the conjugation effect with different incubation time.Our results showed that 20 min is a reasonable incubation time for the SA-QDs coupling to E.coli cells.The fluorescent images,which produce a greatly amplified and enhanced signal of E.coli cells,were obtained through the immunological amplification and fluorescent probe enrichment steps.In addition,the bleaching process of SA-QDs without any encapsulation at room temperature was clearly observed during 10 min of being excited.Our work provided a modularized sample treatment method using SA-QDs as a nano-fluorescent probe in cellular imaging and bio-labeling.     

CdTe/CdS/ZnS 量子点的水相合成及光学特性研究

用巯基乙酸作为稳定剂,采用水相合成的方法合成水溶性CdTe量子点、CdTe／CdS核／壳型量子点和CdTe／CdS／ZnS核／壳／壳型量子点．研究了稳定剂的投入量、反应时间和反应环境pH值等合成条件对这三种量子点发光性能的影响．实验结果表明：通过调节稳定剂的投入量、反应时间和pH值等实验条件,可以实现对量子点光学性质的调节,并使其达到最优值．同时,用X衍射分析仪表征了三种量子点的结构,表明三种量子点具有相同的立方（cubic）晶型结构．     

CdTe/CdS核/壳结构纳米晶量子点的结构及荧光性能

采用水相合成法,制备出核/壳结构CdTe/CdS纳米晶量子点,用红外光谱和X射线衍射对其结构进行了表征,并对CdTe纳米晶量子点光稳定性以及CdTe/CdS纳米晶量子点荧光特性影响因素进行了研究.结果表明:随着放置时间的增加,CdTe量子点的光学稳定性下降;随着反应时间的增加和壳/核比例的增加,CdTe/CdS纳米晶量子点的荧光发射波长均发生红移;且反应时间增加,荧光强度增强;当CdS与CdTe壳/核比例为2∶1时,荧光强度最强.     

生物荧光探针的纳米晶体量子点合成技术进展

纳米晶体量子点最有前途的应用领域是在生物体系中作为荧光探针,量子点的光学特性与传统的有机荧光染料相比有明显的优越性,如具有宽的激发光谱、窄的发射光谱、高的荧光量子产率,寿命更长等优点。本文评述了作为生物荧光探针的量子点的合成及用于生物探针时的量子点表面修饰技术的最新进展。     

生物荧光探针的纳米晶体量子点合成技术进展

纳米晶体量子点最有前途的应用领域是在生物体系中作为荧光探针，量子点的光学特性与传统的有机荧光染料相比有明显的优越性，如具有宽的激发光谱、窄的发射光谱、高的荧光量子产率，寿命更长等优点。本文评述了作为生物荧光探针的量子点的合成及用于生物探针时的量子点表面修饰技术的最新进展。     

Synthesis and properties of water-soluble CdSe/ZnS nanocrystals with the type-I core/shell structure

The synthesis of CdSe/ZnS core/shell nanocrystals though aqueous phase using the coprecipitation method was reported. The influences of factors such as injection methods and dosages of precursors, reaction duration of water-bathing and the initial CdSe：ZnS molar ratio were discussed. In comparison to the CdSe plain core nanocrystals, the CdSe/ZnS core/shell nanocrystals show much brighter photoluminescence demonstrated by the photoluminescence spectra. The epitaxial growth of the core/shell structures was verified by TEM and XRD.     

CdS量子点修饰TiO2纳米管及光解水产氢性能研究

二氧化钛（TiO₂）是一种传统的光催化剂材料,但由于其自身带隙宽(3.2 eV)及光生载流子易复合,往往需要通过贵金属或过渡金属掺杂、阴离子掺杂、构建异质结等手段增强其对太阳光的有效吸收,促使光生载流子分离并抑制其复合。采用两步法构建TiO₂/CdS异质结,首先通过多重电压阳极氧化法制备结构化的TiO₂纳米管阵列,再以TiO₂纳米管为基底,通过化学浴沉积法在TiO₂纳米管管壁内外均匀生长CdS量子点。通过X射线衍射、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)和紫外?可见光谱(UV?VIS)对TiO₂/CdS异质结组成、形貌和光学性质进行了表征。结果表明,构建的TiO₂?CdS异质结有效抑制光生载流子复合,促进激发电子的转移,提高光催化产氢效率;样品TiO₂(1.0)?CdS(1.0)产氢效率达到1.30 mmol/（g?h）,是CdS量子点的1.67倍。最后,基于实验分析提出了可见光光解水制氢过程中光生电子在TiO₂?CdS上的转移机制。     

CdS/Cu2O太阳能电池的制备及膜厚对光电性能的影响

采用水浴法和电沉积法制备CdS/Cu2O复合膜,组装成异质结薄膜太阳能电池。通过改变薄膜的厚度,测试了不同厚度的窗口层和吸收层对太阳能电池性能的影响。实验表明,在400 nm厚的CdS薄膜上沉积30次Cu2O薄膜,所获得的复合膜具有最大的填充因子FF(为0.42)和光电转换效率η(0.05%)。并通过实验发现,适当减少CdS窗口层的厚度,可以提高光的透射率,产生更多的光生载流子,提高了光电转换效率。适当增加Cu2O吸收层的厚度,可以提高光的吸收率,产生更多的光生载流子,提高了光电转换效率。     

基于FPGA的SER/DES在量子密码通讯中的应用

在远距离量子密钥分发(QKD)系统中,使用基于场可编程门阵列(FPGA,field programmable gatearray)的串行器/解串器(SER/DES,serializer/deserializer)技术完成了500 Mbit/s的量子传输速率,利用低频(2 MHz)的同步信号完成对发射方和接收方的同步。根据QKD实验的需要,完成了信号甄别、伪随机数产生器、时间同步和数据编码等功能,成功搭建了基于诱骗态的远距离QKD系统。     

一种新型蛋白质大分子印迹杂化聚合物微球的制备

采用反相悬浮法,通过引入磷酸氢二铵,制备了大分子印迹的磷酸钙/海藻酸钙(CP/CA)杂化微球.研究结果表明,采用本文的制备技术可以方便地获得球形和透明性良好的大分子印迹微球,并且湿态凝胶微球的表观机械强度优于纯海藻酸钙微球.红外光谱测试研究结果表明,微球中出现了新的杂化组分.紫外光谱对重结合行为的研究表明,大分子印迹微球的重结合容量得到显著提高.该基材可以作为一种新的蛋白质大分子印迹聚合物基材.     

Using HF rather than NH4F as doping source for spray-deposited SnO2:F thin films

Fluorine doped tin oxide SnO₂:F thin films were prepared by the spray pyrolysis (SP) technique on glass substrates by using SnCl₂·2H₂O as a precursor and NH4F and HF as doping compounds. A comparison between the properties of the films obtained by using the two doping compounds was performed by using I–V characteristics in the dark at room temperature, AC measurements, and transmittance. It is found that the films prepared by using HF have smaller resistivity, lower impedance and they are less capacitive than films prepared by using NH₄F. In addition, these films have higher transmittance, higher optical bandgap energy and narrower Urbach tail width. These results are interesting for the use of SnO₂:F as forecontact in CdS/CdTe solar cells.