频控变色场致发光器件及机理研究

吸收是发光的前提条件,吸收变了发光的其他特性也会跟着改变。发光寿命长短又会反过来影响吸收的多少,这不仅存在于光致发光中,而且是一个普遍规律。作者从电场引起的场致发光中发现,在同一种材料中掺入两种发光寿命长短相差悬殊的发光中心Cu,Mn,利用激发电源频率的变化明显地显示出器件发光光谱的变化,在一种材料中实现了变色。实验结果证明提高激发频率可以提高短寿命发光中心的激发效率,通过改变激发频率的大小,就可以在掺有两种发光寿命大小不一的材料中实现了发光颜色的变化,这个规律只与发光中心寿命有关,而与激发方式及猝灭原因无关。     

一种在弱酸性介质中有电化学发光性能的鲁米诺衍生物

报道了一种鲁米诺的衍生物-3-(1-乙酰丙酮偶氮)苯二甲酰肼在酸性介质中的电化学发光行为,该化合物与鲁米诺类似,发生两步电化学氧化反应,但其氧化电位较鲁米诺低约0.5V,在氧化铟锡玻璃电极上具有良好的电化学发光性能,有效地避免了氧化铟锡玻璃电极本身的发光干扰.不仅在碱性介质中具有较高的电化学发光效率,而且在酸性介质中也产生较稳定的电化学发光,在1.0×10-6mol/L以上浓度,电化学发光强度与浓度有良好的线性关系.     

彩色发光涂料的光学测量

彩色发光涂料是一种高光效、长余辉的光致发光材料。当对其进行光学测量时,为避免因激发光被探测器接收而对测量结果产生的影响,提出在实验中如何设定特殊的装置,从而保障对发光涂料的光学特性进行有效的测量。根据光度学理论中有关照度和发光亮度的关系,通过实验对三种不同的彩色发光涂料在同样光照条件下的亮度测量,同一种发光涂料在不同颜色光照下的发光亮度比较,以及在彩色发光涂料的亮度衰减情况给出了测量的结果。     

水中流光放电流光丝的再发光和暂停行为

水中流光放电是研究水中放电基本物理、化学过程的主要研究对象.本文利用四分幅超高速相机、采用针-板电极结构、在20—800μS/cm水电导率范围内研究了水中微秒脉冲流光放电流光丝的再发光和暂停行为,探讨了高水电导率下观测不到流光丝的再发光的原因.结果发现:再发光在不同的流光丝之间交替发生并存在两种模式:一种为整根丝熄灭后再发光;一种为只有先端部分发光熄灭随后恢复发光.随着水电导率的增大,观测到流光丝的再发光现象的频度急剧减小, 540μS/cm水电导率时降到零;在20—800μS/cm水电导率条件下都可观测到流光丝伴生冲击波串分段现象,冲击波串分段现象的出现频度在65%以上,表明在20—800μS/cm水电导率条件下流光丝的暂停是一种普遍行为.通过测量两段冲击波的半径差得到流光的暂停时间平均为157 ns,几乎不受水电导率的影响;随着水电导率的增大,流光丝的发光强度显著增大,水电导率大于350μS/cm时,流光丝暂停期间内流光丝的光强度无法衰减到相机分辨水平以下,在相机获得的发光图像上看上去是持续发光的,难以分辨出流光丝"熄灭-再发光"过程.     

得到半导体材料的新方法

很多学者現在正在研究一种新方法:从气相反应直接获得具有任意純度的半导体晶体。这种过程将使半导体二极管和高頻晶体管的生产工艺簡化。在得到这种半导体的反应中,二个碘化鍺分子在晶核表面起反应,而形成一个四碘化鍺分子和一个鍺原子:     

CE为主法,测定化探试样中砷等九元素

选用CE,以碘化铵、沉淀硫、石墨粉为缓冲剂,是多元素分组测定的一种简便快速分析手段,它集中体现目前我国原子发射光谱分析中主要特点和优点。     

有机场致发光中能带模型与分子理论的讨论

在有机场致发光中,能带模型及分子理论从20世纪就存在尖锐的矛盾。在分层优化方案中,经SiO₂加速后的电子能量可以到达10eV,这足以激发发光材料发光,将分层优化方案应用到有机场致发光材料中。发现了固态阴极射线发光(SSCL),经过对它的交叉证明、普适性的验证,肯定了固态阴极射线的发光确实是在发光二极管,无机及有机场致发光之外的一种完全新型的电场诱导的发光。SSCL的特征是在它的光谱中出现短波发光峰,实验证明长波发光峰的减弱是由于电场离化效应。研究了这种效应出现的电压阈值并和SSCL的短波峰出现的电压相比,发现短波峰的出现是在激子的电场离化之后,从而找出了电子处于局域态与扩展态的分水岭,解释了在有机场致发光中能带模型和分子理论并不矛盾,只是适用的条件不同。激子的离化是随电场强度而渐进的变化,因此会有一个两种过程并存的范围。     

粉末材料的场致发光(3)——场致发光的应用

一、场致发光屏的制作 粉末场致发光应用的器件形式,就是做成各种不同类型的发光屏。这种屏的结构类似于一个平板电容器,所以有时候遇到场致发光电容器的称呼。它是由透明导电膜、发光粉和粘结剂、金属电极等主要部分组成的。目前已经实用的有两种,一种是以有机介质作粘结剂、导电玻璃作衬底的玻璃屏,一种是以无机介质作粘结剂、钢板作衬底的搪瓷屏。本文只就有机介质的玻璃屏作一初步介绍。 1.常用制屏工艺。在实验室和工厂中比较常用的制屏方法是刮印法和喷刷法。所谓刮印法,就是把发光粉和粘结剂(如发光     

发光材料的光谱特征(1)

一、发光的颜色 在实际应用中,发光的颜色是很重要的性能之一。用作照明的荧光粉,要求发出和日光相近的白光,并且有好的显色性。黑白电视也需要白光。彩色电视粉由三种材料组成,它们发出三种特定的基色。由此可见,随着使用场合的不同,对发光颜色的要求也就不一样。如何获得所要求的光色,是发光材料研究中的重要课题。     

多孔硅荧光皮秒衰减测量与发光机理分析

荧光光谱、荧光皮秒衰减和红外光谱测量表明,自然氧化多孔硅中有两种不同的发光机理并存,一种是由量子限制效应所决定的,另一种是由氧化引入的发光机理。 关键词：     

Photodynamic Therapy for Cancer Cells Using Metal-Halide Lamps

New metal-halide lamps were developed and their effect on the efficiency of photodynamic therapy (PDT) for cancer cells, murine thymic lymphoma cells (EL-4), was investigated. 5-Aminolevulinic acid-induced protoporphyrin IX was used as a photosensitizer. The metal-halide lamps were made by introducing sodium iodide (Na lamp), lithium iodide (Li lamp), and sodium iodide-lithium iodide mixture (Na-Li lamp) into their discharge tubes. These lamps emitted light in the range of 550 to 750 nm and had specific emission peaks at 580 and 600 nm for the Na lamp, 580, 610, and 680 nm for the Li lamp, and 580, 610, and 675 nm for the Na-Li lamp. Changes in the survival rate of EL-4 with increasing irradiation time indicated that PDT efficiency of the lamps increased in the order Li lamp < Na lamp < Na-Li lamp. We also found that a dark interval during irradiation of the light with the Na-Li lamp enhanced PDT efficiency.     

Gas Phase Emitter Effect of Thulium within Ceramic Metal Halide Lamps in Dependence on Frequency

The gas phase emitter effect within ceramic metal halide (CMH) lamps reduces the effective work function of the electrode material and, therewith, the electrode temperature. An investigation of the gas phase emitter effect of thulium (Tm) within CMH lamps seeded with Tm iodide (TmI3) is carried out. For this purpose, phase resolved images of the arc attachment and measurements of the electrode temperature, Tm atom and ion densities are performed in dependence on operating frequency by pyrometry and optical emission spectroscopy. Additionally, the influence of a sodium iodide (NaI) admixture is studied. The emitter effect is generated by means of a monolayer of Tm atoms on the electrode surface generated by a Tm ion current within the cathodic phase. It overlaps onto the anodic phase at higher frequencies of some hundreds of hertz. The reason is the finite life time of the monolayer, which is determined by the adsorption energy of Tm on the tungsten surface. Due to the low electric field strength in front of the anode and the mass inertia, the emitter ions and atoms remain in front of the anode. They retard the decay of the monolayer and with it the increase of the work function. Moreover, a comparison of a lamp seeded with TmI3 and sodium iodide (NaI) with a lamp seeded only with TmI3 illustrates a slight reduction of the electrode tip temperature caused by a higher Tm saturation vapour pressure and a higher Tm amount within the lamp filling. The influence of Na appears to be quite low. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Electric-discharge He/Xe/I<Subscript>2</Subscript> excimer-halogen UV lamp

The characteristics of a low-size low-pressure UV lamp operating on the atomic iodine resonant line (λ=206 nm) and xenon iodide (λ=253 nm) and dimer iodine (λ=342 nm) bands are investigated. A lamp with an interelectrode distance of 19 cm was pumped by a longitudinal dc glow discharge. The working gas mixtures were He/I₂ and He/Xe/I₂ mixtures with a total pressure of 50–1500 Pa. The output parameters of the electric-discharge excimer-halogen lamp were optimized in terms of the gas mixture pressure and composition and the power deposited in the discharge. It is shown that the total UV power emitted from the entire aperture of the lamp in the spectral range 200–350 nm attains 5–7 W with an efficiency of ≤5%.     

Temperature and concentration dependences of thermal conductivity of solid solutions of gadolinium and dysprosium sulfides

Thermal conductivity of a number of solid solutions of gadolinium and dysprosium sulfides has been studied experimentally within the temperature range 80-400 K. The work offers the data on thermal conductivity coefficient and lattice thermal conductivity of the studied samples. It was found that replacement of gadolinium ions by dysprosium ions leads to significant decrease of the samples?? thermal conductivity and changes its temperature dependence character due to the resonance scattering of phonons by paramagnetic ions of dysprosium. Influence of this mechanism of phonon scattering conditions the area of anomalous change observed on the concentration dependence of thermal conductivity coefficient.     

Near Infrared Broadband Emission from Bismuth-Dysprosium Codoped Chalcohalide Glasses

We investigate the broadband infrared emission of bismuth doped and bismuth/dysprosium codoped chalcohalide glasses. It is found that the bismuth/dysprosium codoping can drastically enhance the f/uorescence as compared with either bismuth or dysprosium doped glasses. Meanwhile, the full width at half maximum of bismuth/dysprosium codoped glasses is over 170 nm, which is the largest value among all the reported rare-earth doped chalcohalide g/asses. An ideal way for energy consumption between bismuth and dysprosium ions is supposed. Such improved gain spectra of both bismuth and dysprosium ions may have potential applications in developing broadband fibre amplifiers.     

Passive mode-locking of a Coumarin dye laser from 505–520 nm using DOCI as the saturable absorber

We report the passive mode-locking of a flash lamp pumped dye laser operating with a mixture of Coumarin 500^F and Coumarin 504 lasing dyes using DOCI (3,3'-diethyl oxacarbocyanine iodide) as the saturable absorber. We also suggest the formation of a transient photoisomer to be responsible for the mode-locking obtained with DOCI at long wavelengths, where the normal form has a very low absorption cross section.     

基于多峰协同和纯元素特征峰面积归一化的重叠峰快速解析算法

由于元素间特征峰的相互干扰,受实验仪器能量分辨率的影响,当多个元素的特征峰峰位相近且展宽较宽时就会形成重叠峰。以分离度低且分解需求精度高的重叠峰为研究对象,提出一种基于多峰协同和纯元素特征峰面积归一化的重叠峰快速解析算法,并结合实际的X射线荧光光谱进行了新方法的验证。选取镝铁合金的X射线荧光光谱图作为实例,在该实验条件下镝L_α特征峰和铁K_α特征峰形成的重叠峰分离度约为0.273 5,同时还存在分离度较大但荧光产额较低的镝L_β特征峰和铁K_β特征峰。首先,配置浓度范围(7.8～8.2 mg·mL^-1)的镝标液和浓度范围(1.8～2.2 mg·mL^-1)的铁标液进行测量获取到纯元素谱图,分别进行面积归一化处理并取平均得到镝L_α峰和铁K_α峰的归一化特征峰。然后,使用镝、铁标液混兑出铁元素质量百分比范围在19.1%～21%,梯度为0.1%的20组样品液进行测量。由于重叠峰部分仅由镝L_α峰和铁K     

Partial Phonon Density of States of Dysprosium and its Compounds Measured Using Inelastic Nuclear Resonance Scattering

Inelastic nuclear resonance scattering measurements, utilizing a submilli eV monochromator, were performed on natural Dy metal, dysprosium oxide, and intermetallic Laves and Chevrel phase dysprosium compounds. The inelastic spectrum directly yields the partial phonon density of states, and thus provides a wealth of information about the modes of vibration occurring in a lattice at the Mössbauer Dy site. The extraction of the partial phonon density of states from a broad range of materials containing dysprosium demonstrates the feasibility of material science studies.     

Investigation of the luminescence properties and thermal stability of dysprosium,terbium, and europium ions singly- and co-doped strontium yttrium borate phosphors

A series of trivalent rare-earth element ions (europium, terbium, dysprosium) singly- and co-doped strontium yttrium borate phosphors was synthesized via the sol–gel method. The phase formation, luminescence properties, decay times, and energy transfer behaviors from terbium ions to europium ions, the thermal stability, and the Commission Internationale de L’Eclairage coordinates were investigated. Under the excitation of ultraviolet light, the singly doped phosphors exhibited green emission of terbium ions, white emission of dysprosium ions, and red emission of europium ions, respectively. For the terbium and europium ions co-doped strontium yttrium borate samples, a white emission can be realized by blending the doping concentration of terbium and europium ions. The critical distance between terbium and europium ions has been calculated to be about 14.52?Å and the energy transfer from terbium to europium occurred through the dipole–quadrupole interaction. At 150°C, the emission intensity of terbium and europium in the 12?mol% terbium and 14?mol% europium co-doped strontium yttrium borate sample was maintained at about 74% and 87% of their corresponding initial values, respectively, and the dysprosium ions singly doped strontium yttrium borate sample showed about 70% of its initial emission intensity at room temperature. The above results suggested that europium, terbium, dysprosium ions singly- and co-doped strontium yttrium borate phosphors have potential applications as ultraviolet-convertible phosphors.     

Magnetic dimensionality of Y(2−x)DyxBaCuO5

In this communication, we report the effect that doping Y₂BaCuO₅ with Dy has on its two-dimensional (2D) magnetic structure. Pure samples at both ends of the series, as well as samples doped with 1, 5, 10 and 25% dysprosium, have been characterised using X-ray diffraction, and AC susceptibility together with neutron diffraction studies on the 1 and 5% samples, which were used to measure the magnetic ordering at low temperatures. The results show that 1% Dy is enough to disrupt the 2D magnetic ordering turning it into a 3D array. The low dysprosium concentration indicates that the 3D ordering is achieved without the existence of a rare earth magnetic sublattice. The change in the ordering temperature from 27 K for the pure Y₂BaCuO₅ to 16 K for the 1 and 5% Dy compounds, together with the parameters from the AC susceptibility fittings, reveal that the effect of the Dy doping affects the electronic structure of the Cu ions that become involved in the superexchange pathways. The discrepancy between the parameters obtained by the Curie-Weiss fittings of the real part of the AC susceptibility and the neutron diffraction results, shows that the exchange mechanism deviates from the mean field model for all dysprosium concentrations.