金属离子修饰的ZnS/PAMAM纳米复合材料的荧光性能研究

用荧光分光光度法研究了Zn2+,Mn2+,Cd2+,Na+,K+,Ag+,Cu2+和Pb2+等金属离子修饰的ZnS/PAMAM树形分子纳米复合材料的荧光发射性能。结果表明：不同金属离子修饰效果不同。Zn2+,Mn2+和Cd2+修饰后,ZnS/PAMAM树形分子纳米复合材料的荧光发射强度有不同程度提高;Ag+,Cu2+和Pb2+的修饰对荧光有不同程度的猝灭作用;而Na+和K+的修饰对荧光发射无明显影响。与修饰前相比,Cd2+离子修饰的ZnS/PAMAM树形分子纳米复合材料标记的潜指纹发射的蓝色荧光更加明亮,与背景反差更加明显。这对提高潜指纹的显现精度和准确率有很好的借鉴价值。     

CdS/PAMAM树形分子纳米复合材料的荧光性能研究

采用荧光发射法研究了不同Cd2+与树形分子的摩尔比(负载比)条件下硫化镉(CdS)/聚酰胺-胺(RAMAM)树形分子纳米复合材料(NCs)水溶液的荧光性能,并探索了其荧光产生的机理.结果表明:在波长330 nm光的激发下,CdS/G4.0-NH2PAMAM NCs的荧光发射光谱中出现了2个峰,一个是PAMAM树形分子的...     

组分对Cu-Zn-In-S/ZnS核壳量子点发光性能的影响

利用热注射法通过调控Cu/Zn比例制备了不同组分的Cu-Zn-In-S/ZnS核壳量子点,通过紫外-可见吸收光谱以及稳态和时间分辨光谱分析Cu/Zn比例对量子点发光性能的影响.结果表明,不同组分Cu-Zn-In-S/ZnS核壳量子点呈现闪锌矿结构且晶粒尺寸接近;随着Cu/Zn比例的减小,Cu-Zn-In-S/ZnS核壳量子点的带隙变宽,导致吸收光谱发生蓝移;当Cu/Zn比例从6/1减小到1/6时,量子点的发光峰位从640nm蓝移529nm.由于Zn2+替代Cu+能够减少Cu原子缺陷的形成,从而提高了量子点的荧光效率;当Cu/Zn=1/6时,样品中观测到Cu+离子发光和较长的荧光寿命.     

表面修饰的ZnS:Mn量子点的发光性质及其对生物分子的检测

采用水热法制备了ZnS:Mn量子点,探讨了掺杂离子浓度对ZnS:Mn量子点的晶体结构和发光性质的影响。通过荧光光谱对样品进行表征。结果表明:掺杂离子的摩尔分数达到2%时,ZnS:Mn量子点在595 nm附近的发光最强;继续增加掺杂浓度反而出现荧光猝灭的现象。本文还研究了表面修饰对量子点形貌和发光性质的影响。通过透射电子显微镜(TEM)观察样品的形貌,发现经过3-巯基丙酸(MPA)修饰后的样品表面团聚现象得到改善,并且尺寸单一、单分散性较好,平均粒径约为5 nm。经过修饰后的样品减少了表面非辐射性缺陷中心,使掺杂Mn2+所引起的595 nm附近的发射峰强度增大。将MPA修饰后的ZnS:Mn量子点与牛血清白蛋白(BSA)分子进行生物偶联,并利用BCA法对偶联上的蛋白含量进行定量检测,结果显示经过修饰后的量子点偶联蛋白的能力更强。     

Er/Li离子共掺ZnS量子点的水相法合成及性能

水相法合成Er/Li离子共掺ZnS量子点,并对其进行结构表征、形貌观察和荧光性能分析.结果表明:水相法合成的闪锌矿结构的Er/LiZnS量子点,形貌近似球形,粒度大小约为10nm.Er/Li∶ZnS量子点的发光峰为445nm和470nm,分别对应S空位缺陷发光和Zn空位发光,表明Er3+和Li+的掺杂对紫外-可见波段的荧光峰没有影响.     

脂溶性CdSe/ZnS量子点脂质体复合物的制备及表征

在油相中成功合成了脂溶性CdSe/ZnS核壳量子点纳米粒,粒径平均为4.5 nm,量子产率达29%,发射波长为540 nm。通过薄膜分散法,以蛋黄卵磷脂、胆固醇为膜材,将脂溶性的CdSe/ZnS核壳量子点包覆于脂质体磷脂双分子层中,由于磷脂分子的两亲性,使得脂溶性的CdSe/ZnS核壳量子点同时又具有亲水性。通过透射电镜对脂质体形态进行了表征,倒置荧光显微镜证实了发光CdSe/ZnS核壳量子点成功包埋于脂质体双分子层中,包裹的发光CdSe/ZnS核壳量子点具有更稳定的发光及抗光漂白性质。     

ZnO@SiO_2核壳量子点的制备及其荧光性能的研究

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 H7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。     

2-(3’,4’-二羧基苯氧基)苯甲酸配体桥联的锌(Ⅱ)配合物的合成、结构及荧光性质

以2-(3’,4’-二羧基苯氧基)苯甲酸(H3DPBA)和1,3-二(4-吡啶基)-丙烷(bpp)为配体,与Zn(Ac)2通过水热反应,获得了一维链状配合物Zn(DPBA)(bpp)。该配合物的一个不对称单元包括一个Zn(Ⅱ)离子,一个DPBA配体和一个bpp配体。Zn(Ⅱ)离子与四个氧原子及一个氮原子配位,其配位数为5。固态配合物在375nm处出现强的发射峰,来自于配体的π~*—π跃迁。与配体的荧光发射光谱比较,配合物的荧光发射峰发生了蓝移,而且配合物的荧光发射强度有大幅度增强。讨论了配合物在常见溶剂中和金属阳离子中的荧光性质。实验结果表明不同有机小分子或不同金属阳离子对配合物的荧光强度有不同程度的影响,有机小分子硝基苯和Fe~(3+)使配合物荧光猝灭,该Zn(Ⅱ)-配合物可用于硝基苯的检测以及水和乙醇体系中Fe~(3+)的检测。     

一种基于C＝N异构化的高选择性镁离子荧光探针

设计合成了荧光传感分子2-羟基-1-萘甲醛缩1-氨基海因(L),通过吸收和荧光光谱研究其对金属离子的识别作用,结果表明该化合物对镁离子表现出高选择性响应,在最大发射波长448nm处,乙腈中加入Mg2+,荧光强度增强30倍,Job曲线表明该受体分子与Mg2+以2∶1计量比配位,并初步探讨了该受体分子与镁离子的结合模式和荧...     

三维超分子配合物[Zn（C_（12）H_8N_3）_2·H_2O]的水热合成、晶体结构及光致发光1

通过水热法合成了一种三维超分子配合物Zn（C12H8N3）2.H2O,经元素分析、紫外和红外光谱对其进行表征。用X射线单晶衍射测定了其晶体结构,该配合物晶体属单斜晶系,P21/c空间群,晶胞参数为：a=1.25239（10）nm,b=1.30233（11）nm,c=1.33167（11）nm,β=102.6950（10）°,Z=4,[Zn（C12H8N3）2.H2O],Mr=471.81,V=2.1189（3）nm^3,Dc=1.479g·cm^-3,μ=1.189mm^-1,F（000）=968,R1=0.0300,WR2=0.1017,GOF=1.005。该化合物由1个Zn（Ⅱ）离子、2个2-（2-吡啶基）苯并咪唑阴离子和1分子配位水组成。其中2-（2-吡啶基）苯并咪唑的1位氮原子、吡啶环上氮原子及水分子中氧原子与锌（Ⅱ）离子配位,形成五配位的畸变三角双锥结构,单胞分子之间通过氢键O（w）-H…N和π-π堆积作用相互构成三维网状超分子体系。固态荧光测试显示,该配合物具有强的蓝色荧光发射（λmax=456nm）。     

The optical properties and energy transition process in nanocomposite of polyvinyl-pyrrolidone polymer and Mn-doped ZnS

This study has been carried out on the optical properties of polyvinyl-pyrrolidone (PVP), the energy transition process in nanocomposite of PVP capped ZnS:Mn nanocrystalline and the influence of the PVP concentration on the optical properties of the PVP capped ZnS:Mn nanocrystalline thin films synthesized by the wet chemical method. The microstructures of the samples were investigated by X-ray diffraction, the atomic absorption spectroscopy, and transmission electron microscopy. The results showed that the prepared samples belonged to the sphalerite structure with the average particle size of about 2–3 nm. The optical properties of samples are studied by measuring absorption, photoluminescence (PL) spectra and time-resolved PL spectra in the wavelength range from 200 to 700 nm at 300 K. From data of the absorption spectra, the absorption edge of PVP polymer was found about of 230 nm. The absorption edge of PVP capped ZnS:Mn nanoparticles shifted from 322 to 305 nm when the PVP concentration increases. The luminescence spectra of PVP showed a blue emission with peak maximum at 394 nm. The luminescence spectra of ZnS:Mn–PVP exhibits a blue emission with peak maximum at 437 nm and an orange–yellow emission of ion Mn²⁺ with peak maximum at 600 nm. While the PVP coating did not affect the microstructure of ZnS:Mn nanomaterial, the PL spectra of the PVP capped ZnS:Mn samples were found to be affected strongly by the PVP concentration.     

Effect on photophysical properties of colloidal ZnS quantum dots by doping with cobalt, copper, and cobalt�Ccopper mixtures

Colloidal ZnS quantum dots (QDs) are prepared by passing H₂S gas through a solution of Zn(CH₃COO)₂ in acetonitrile. Photophysical properties are investigated using UV?CVisible and photoluminescence (PL) spectroscopy. The spectrum shows an absorption shoulder at 271 nm representing a band gap of 4.6 eV. The doping of ZnS QDs with Co, Cu, and a mixture of Co and Cu not only increased the band gap to 0.2 eV but also turns these otherwise colorless QDs to blue in color due to cobalt, and green due to Cu. The observed emission in the visible region suggests that the dopants may have induced additional excited states to the ZnS QDs. This absorbance in the visible region can be utilized in the optoelectronic applications.     

Growth of single-crystal ZnS nanobelts through a low-temperature thermochemistry route and their optical properties

ZnS nanobelts have been synthesized on a large scale using a simple thermochemistry method where the sources were Zn and ammonium polysulphide. The nanobelts had a uniform single-crystal hexagonal wurtzite structure with width ranging from 50 to 150 nm and length up to several tens of micrometers. The growth of ZnS nanobelts is controlled by vapor-solid (VS) crystal growth mechanism. Photoluminescence (PL) measurement shows that the nanobelts have a strong blue emission at about 450 nm and a green light emission at 530 nm. PACS 73.61.Ga; 78.55.Et; 81.15.Gh; 68.37.Hk; 68.37.Lp     

Synthesis and characterization of Cu doped ZnS nanoparticles using TOPO and SHMP as capping agents

Undoped and Cu²⁺ doped (0.2-0.8%) ZnS nanoparticles have been synthesized through chemical precipitation method. Tri-n-octylphosphine oxide (TOPO) and sodium hexametaphosphate (SHMP) were used as capping agents. The synthesized nanoparticles have been analyzed using X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectrometer (FT-IR), UV-vis spectrometer, photoluminescence (PL) and thermo gravimetric-differential scanning calorimetry (TG-DTA) analysis. The size of the particles is found to be 4-6 nm range. Photoluminescence spectra were recorded for ZnS:Cu²⁺ under the excitation wavelength of 320 nm. The prepared Cu²⁺-doped sample shows efficient PL emission in 470-525 nm region. The capped ZnS:Cu emission intensity is enhanced than the uncapped particles. The doping ions were identified by electron spin resonance (ESR) spectrometer. The phase changes were observed in different temperatures.     

Enhanced visible light emission from Co doped ZnS nanoparticles

ZnS nanoparticles with Co²⁺ doping have been prepared at room temperature through a soft chemical route, namely the chemical co-precipitation method. The nanostructures of the prepared nanoparticles have been analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), selected-area electron diffraction (SAED), and UV-vis spectrophotometer. The sizes of as prepared nanoparticles are found to be in 1–4 nm range. Room-temperature photoluminescence (PL) spectrum of the undoped sample exhibits emission in the blue region with multiple peaks under UV excitation. On the other hand, in the Co²⁺ doped ZnS samples enhanced visible light emissions with emission intensities of ~35 times larger than that of the undoped sample are observed under the same UV excitation wavelength of 280 nm.     

Preparation, characterization and study of optical properties of ZnS nanophosphor

In this work the preparation, characterization and photoluminescence studies of pure and copper-doped ZnS nanophosphors are reported, which are prepared by using solid-state reaction technique at a temperature of 100 °C. The as-obtained samples were characterized by X-ray diffraction (XRD) and UV-VIS Reflectance spectroscopy. The XRD analysis confirms the formation of cubic phase of undoped as well as Cu²⁺-doped ZnS nanoparticles. Furthermore it shows that the average size of pure as well as copper-doped samples ranges from 15 to 50 nm. The room-temperature PL spectra of the undoped ZnS sample showed two main peaks centered at around 421 and 450 nm, which are the characteristic emissions of interstitial zinc and sulfur vacancies, respectively. The PL of the doped sample showed a broad-band emission spectrum centered at 465 nm accompanied with shoulders at around 425, 450 and 510 nm, which are the characteristic emission peaks of interstitial zinc, sulfur vacancies and Cu²⁺ ions, respectively. Our experimental results indicate that the PL spectrum confirms the presence of Cu²⁺ ions in the ZnS nanoparticles as expected.     

Synthesis, characterization and optical properties of water-soluble ZnS:Mn nanoparticles

ZnS nanoparticles with Mn²⁺ doping (0.5-20%) have been prepared through a simple chemical method, namely the chemical precipitation method. The structure of the nanoparticles has been analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and UV-vis spectrometer. The size of the particles is found to be 3-5 nm range. Photoluminescence spectra were recorded for undoped ZnS nanoparticles using an excitation wavelength of 320 nm, exhibiting an emission peak centered at around 445 nm. However, from the Mn²⁺-doped samples, a yellow-orange emission from the Mn²⁺⁴T₁-⁶A₁ transition is observed along with the blue emission. The prepared Mn²⁺-doped sample shows efficient emission of yellow-orange light with the peak emission 580 nm with the blue emission suppressed. The maximum PL intensity is observed only at the excitation energy of 3.88 eV (320 nm). Increase in stabilizing time up to 48 h in de-ionized water yields the enhancement of emission intensity of doped (4% Mn²⁺) ZnS. The correlation made through the concentration of Mn²⁺ versus PL intensity resulted in opposite trend (mirror image) of blue and yellow emissions.     

Hydrothermal synthesis and optical properties of full-color-emission ZnS:Cu, Al nanocrystals

ZnS:Cu, Al nanocrystals were synthesized by a hydrothermal method at 200 degrees C and their optical properties were studied. The analysis of XRD and TEM show that the spherical-like nanocrystals had a grain size of approximately 15 nm and were well dispersed, with a zinc blende structure. The energy dispersive X-ray spectroscopy (EDX) and atomic absorption spectrometry were applied to the analysis of S, Zn and Cu content in the sample. The results proved that a large number of zinc vacancies exist and Cu is incorporated into the sample lattice. The photoluminescence (PL) spectra were investigated. The PL mechanism is discussed. The excitation spectrum is broad. Under 337 nm excitation the sample emits bright green light. Under 370-410 nm excitation the sample emits white light. The broad emission spectra are almost coincident with any excitation wavelength of between 370 and 410 nm making them attractive as conversion phosphors for LED applications and full-color fluorescence display devices. The emitted white light under 375 nm excitation was found to be the result of blue, green, and orange emission bands. For Cu/Zn, Cu/Al and S/Zn molar ratios of 3 x 10(-4), 2 and 3, respectively, the near blue white light can be observed with the naked eye in daylight.