Synthesis and Photoluminescence of New Europium Complex Eu(DBM)_3(DPPZ) with Dipyridophenazine Ligand

Dipyrido [3, 2-a:2,3-c] phenazine moiety has been introduced as neutral ligand in europium complex. Therefore, a new europium complex with saturated emission, strong fluorescent intensity and good solubility was designed and synthesized for the first time. Its photoluminescence and UV properties were examined. The experimental results showed that this new Eu-complex could be used as red electroluminescent materials.

Red Electroluminescence and Photoluminescence from Novel Binuclear Europium Complex with Squaric Acid Ligand

A novel binuclear europium P-diketone complex with squaric acid ligand was synthesized for the first time. Its structure was elucidated by IR, UV, and Elemental Analysis. Red light emitting diode (LED) was fabricated by using the novel europium complex as an emitting layer, tris(8-quinolinolate) aluminum (III) (Alq(3)) as an electron-transporting layer, N, N'-diphenyl-N, N'-(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD) as a hole-transporting layer. A cell structure of indium-tin-oxide/TPD/Eu-complex/Alq(3)/Mg: Ag was employed. Red electroluminescence was observed at room temperature with dc bias voltage of 2 V in this cell. 2 Red emission peaks at about 613 nm with maximum luminance of over 106 cd/m(2). Compared with the EL luminance from those europium complexes reported before, one from the Eu-complex is best in the same cells.

Red Mechanoluminescence and Photoluminescence from Novel Europium Complexes

Two new binuclear (europium and lanthanum) beta-diketone complexes Eu0.9La0.1(TTA)(3)Phen and Eu0.5La0.5(TTA)(3)Phen in which Phen is 1,10-phenanthroline, TTA is an anion of thenoyltrifluoroacetone (HTTA) were synthesized for the first time. They showed intense photoluminescence (PL) and mechanoluminescence (ML), and had their maximum PL and ML spectra peaked at 613.5 nm with half bandwidth of 10 nm respectively. Their PL and ML intensity were obviously stronger than these from Eu(TTA)(3)Phen. It is considered that binuclear (europium and lanthanum) beta-diketones complexes are promising ML and PL materials.

Photoluminescence Spectra of Disordered and Ordered Ga_(0.52)In_(0.48)P

Temperature-dependence and excitation-intensity-dependence of photoluminescence spectra for both disordered and ordered Ga 0.52 In 0.48 P are measured. The disordered sample is characterized by its single peak photoluminescence spectrum which is excitation-intensity independent and has different activation energy at different temperature region. The ordered sample shows double peaks, the intensity of the high-energy peak has an anomalous increase firstly and quenches afterwards. The relative phenomena are reasonably explained in terms of lattice ordering and orientation superlattice model.

The Photoluminescence Spectra of the Aeschynite Group Minerals

Raman and photoluminescence spectra of the metamict and annealing recrystallization titanoaeschynite-(Nd) and nioboaeschynite-(Ce), found in Baiyunobo mineral deposit in China, were measured and discussed. The peaks or bands in the spectra of the metamic minerals are weak, broad and diffuse, but sharpen notably after heating. The results show that the distortion of the structure and disorder state of the elements exists in the minerals when natural crystalline minerals transformed in-to metamict minerals after a long period of self-irradiation structure damaging. And all bands in the photoluminescence spectra of the aeschynite group mineral stem from emission transitions of Nd3+, when 514.5 nm laser is used as the excitation source.

Time-Resolved Photoluminescence Spectra of Porous Si

he photoluminescence spectra of porous Si have been studied. Its timere-solved luminescence spectra show a red shift of luminescencc peak with increasingdelay time after exciting and a nonexponential decay. Several spectral bands withdifferent Gaussian center appear by means of the decomposition of a spetrum. Theresuits of our experiments show quantum confined characters in porous Si, and wespeculate that the short wavelength band at 465 nm is the direct band froni P_(15) toP_(25)

PLE spectra analysis of the sub-structure in the absorption spectra of CdSeS quantum dots

The semiconductor CdSeS quantum dots （QDs） embedded in glass are analysed by means of absorption spectra, photoluminescence （PL） spectra and photoluminescence excitation （PLE） spectra. The peaks of absorption spectra shift to lower energies with the size of QD increasing, which obviously shows a quantum-size effect. Using the PLE spectra, the physical origin of the lowest absorption peak is analysed. In PLE spectra, the lowest absorption peak can be deconvoluted into two peaks that stem from the transitions of 1S3/2-1Se and 2S3/2-1Se respectively. The measured energy difference between the two peaks is found to decrease with the size of QD increasing, which agrees well with the theoretical calculation for the two transitions. The luminescence peak of defect states is also analysed by PLE spectra. Two transitions are present in the PLE, which indicates that the transitions of 1S3/2 1Se and 2S3/2 1Se are responsible for the defect states luminescence.

Photoluminescence of Por-Si with High-ordered Mosaic Structure Received at Long Anodic Etching p-Si (100) in the Electrolyte with an Internal Current Source

Photoluminescence spectra and nature of light-emitting centers of a porous silicon (por-Si) samples are given. The por- Si samples had high-ordered mosaic structure, which was received under long anodic etching p-Si(100) in electrolyte with an internal current source. The photoluminescence spectra were monitored at room temperature before and after annealing in air and vacuum. Comparative analysis of photoluminescence spectra of the por-Si samples annealed at different temperatures in air and vacuum shows that the thermal annealing conditions has significant effect on the intensity and spectral content of the photoluminescence spectra. The nature of the luminescence emission centers at different temperatures and annealing conditions was discussed.

Fabrication and photoluminescence characteristics of nonuniform Yb-Er codoped films

The nonuniform Yb-Er Codoped Al2O3 films were prepared on SiO2/Si substrates using a medium frequency magnetron sputtering system. Two asymmetry targets in the system were introduced to realize the nonuniform dopant. Some curves of Photoluminescence （PL） peak intensity were obtained by adjusting the deposition parameters, such as, the pillar number of erbium and ytterbium in the mixed target and the distance between a sample table and targets. Typically, the curve of PL peak intensity against the offset distance was approximately linear. The ratio of the PL intensity at the two ends of the same sample was 12.6 and the slope was 71.83/mm when the pillar numbers of the erbium and ytterbium in the mixed target are 5 and 60, respectively, and the distance between targets and the sample table is 2.9 cm.

Intense Yellow Photoluminescence from Silicon Oxynitride Films Prepared by Dual Ion Beam Sputtering

In this work, results on the study of the structure and photoluminescence (PL) properties of SiOxNy thin films are presented. The films were deposited at room temperature using a dual-ion-beam co-sputtering system. The XRD and TEM results show that the deposited films have an amorphous structure. In the XPS result, we find N 1s spectra consist of one symmetric single peak at 397.8 eV, indicating that the nitrogen atoms are mainly bonded to silicon. It is in agreement to the result of FTIR. In SiOxNy films, an intense single PL peak at 590 nm is observed. Furthermore, with the increase of the N content in the SiOxNy films, the intensity of the PL peak at 590 nm increases a lot. The PL peak of 590 nm is suggested to originate from N-related defects.

Silicon carbide nanotubes with special morphology prepared by super critical hydrothermal method and photoluminescence character

Silicon carbide nanotubes（SiCNTs） with special morphology synthesized by supercritical hydrothermal method at 470 C and 8 MPa have been reported in this paper.SiCNTs with special morphology were characterized by transmission electron microscopy（TEM） and high-resolution TEM（HRTEM）.There are two kinds of silicon carbide with special morphology：One is oval SiCNTs with small aspect ratio,the other is bamboo cone-shape structure.SiCNTs have been analyzed by fluorescence spectrometer.The results indicate that the SiCNTs have strong photoluminescence（PL） property.The SiCNTs with oval shape are one kind of intermediate state of growth process of nanotube.The growth mechanism of silicon nanotubes has been proposed based on experiment data.The investigations of growth mechanism of SiCNTs with bamboo structure show that the defect produced in the growth process play the important role in SiCNTs with special structure.

Effect of different catalysts and growth temperature on the photoluminescence properties of zinc silicate nanostructures grown via vapor-liquid-solid method

We explore the photoluminescence properties of zinc silicate(Zn_(2)SiO_(4)) nanostructures synthesized by vapor-liquidsolid(VLS)mode of growth using three different catalysts(Sn,Ag,and Mn).Different catalysts significantly influence the growth rate which in turn has an impact on the structure and hence the photoluminescence of the prepared zinc silicate nanostructures.Zn_(2)SiO_(4) has a wide bandgap of about 5.5 eV and in its pure form,it does not emit in visible region due to its inner shell electronic transitions between the 3 d5 energy levels.However,the incorporation of different catalysts(Sn,Ag and Mn)at different growth temperatures into the Zn_(2)SiO_(4) crystal growth kinetics provides wide visible spectral range of photoluminescence(PL)emissions.PL analysis shows broad multi-band spectrum in the visible region and distinct colors(red,yellow,green,blue,cyan and violet)are obtained depending on the crystalline structure of the prepared nanostructures.The allowed transitions due to the effect of different catalysts on zinc silicate lattice offer a huge cross-section of absorption that generates strong photoluminescence.The correlation between the structural and optical properties of the synthesized nanostructures is discussed in detail.The synthesized photoluminescent nanostructures have potential applications in solidstate lighting and display devices.

直流磁控溅射ZnO薄膜的结构和室温PL谱

用直流反应磁控溅射法在硅衬底上沉积 C轴择优取向的 Zn O晶体薄膜 ,薄膜呈柱状结构 ,柱状晶直径约为10 0 nm,晶柱内为结晶性能完整的单晶 ,而晶界处存在较大的应力 .Zn O薄膜在 He- Cd激光器激发下有较强的紫外光发射 ,晶界应力引起 Zn O禁带宽度向长波方向移动 ,提高衬底温度有利于降低晶界应力和抑制深能级的绿光发射 .

基于傅里叶变换红外光谱和siPLS-GA-PLS的水稻叶片氮素含量预测研究

傅里叶变换中红外光谱谱区宽,搜索空间大,需要采用高效率和高质量的算法进行波长选择.敏感波段及其组合的选择是简化分析模型和提高模型预测精度的关键技术之一.本研究以水稻孕穗期叶片干样的中红外光谱透射率和叶片氮素含量为数据源,通过协同偏最小二乘算法（siPLS）从宽谱区中初选出波段范围1583.3-992.2cm^-1,再采用迭代遗传算法（GA）从中选出了84个水稻叶片氮素含量预测的敏感波段.研究结果显示以此敏感波段建立的偏最小二乘回归模型的预测均方根误差（RMSEP）和水稻叶片总氮含量的测量值与预测值之间的相关系数分别为0.1186和0.9120,该预测结果明显优于协同偏最小二乘法（siPLS）和光谱指数NFSA的预测结果,说明傅里叶变换红外光谱技术结合siPLS-GA-PLS算法能够实现水稻叶片氮素含量的预测.

PLS-近红外漫反射光谱法分析磺胺甲基异唑

偏最小二乘（ＰＬＳ）法同近红外漫反射光谱法结合，分析了粉末药品磺胺甲基异唑．讨论了波长对ＰＬＳ定量预测能力的影响．对照样品和试样的预测结果的ＲＳＤ分别为０．１１％和０．５６％，结果令人满意．

PLS回归法建立适应温度变化的近红外光谱定量分析模型

研究了近红外光谱定量分析模型对于样品温度的适应性。以 4 2个不同品种的大豆为实验材料 ,用 2台光谱仪分别独立测定了样品在 5种温度下的近红外光谱。对于 2台光谱仪测定的光谱 ,均依据光谱信息选择部分光谱 ,采用PLS回归法对大豆样品的粗蛋白质和粗脂肪含量分别建立了近红外光谱定量分析模型 ,并以剩余样品对模型进行预测检验。 4个模型的预测结果均表明 :超过 94 %的检验样品的预测相对误差小于 5 % ,说明了预测样品处于 5～ 4 0℃时 ,模型都有较好的预测效果。

PLS-BP法近红外光谱定量分析研究

建立BP模型用于近红外光谱定量分析时,为克服所建模型与训练样本集产生“过拟合”,先用线性算法为其压缩训练数据是必要的。目前多采用主成分法(PCA)和逐步回归法(SRA)。主成分法具有极强的压缩数据能力,用它压缩成的主成分输入BP网所建模型的预测精度一般能满足要求,但它处理数据时未考虑输出变量的影响。逐步回归法根据系统输出选择变量,但所选变量具有自相关性,而且与训练集样品的排列顺序有关,很难选出最好的变量,往往难满足预测精度要求。本研究用偏最小二乘法(PLS),根据输出变量将原始数据压缩为主成分,输入BP网并用所建模型预测30个小麦样品的蛋白质含量。结果表明,与PCA-BP模型的预测决定系数(R2)从92.50提高到97.10,训练迭代次数从12 000减少到4 500。

基于OSC/PLS的茶叶中EGCG含量的近红外光谱法测定

采用正交信号校正法(OSC)对茶叶的近红外光谱进行预处理,并结合偏最小二乘法(PLS)建立表没食子儿茶素没食子酸酯(epigallocatechin gallate,EGCG)含量的预测模型。PLS校正模型采纳的最佳因子数会随着OSC因子的增加而逐渐减少以达到简化模型的效果。试验以预测残差平方和(PRESS)来评价模型的整体性能,当滤除前6个OSC因子时为最佳,此时校正模型采纳的PLS因子数为5,校正时的相关系数r2和校正标准偏差SEC分别为0.955 90和0.38279,预测时的相关系数r2和预测标准偏差SEP分别为0.936 61和0.444 13。研究结果表明,应用近红外光谱法结合OSC/PLS可以快速准确地测定茶叶中EGCG的含量。

基于PLS投影分析的光谱波段选择方法

光谱测量数据需要对其进行波长选择以提高模型预测精度和简化模型。文章提出了一种基于PLS投影相关系数的快速、准确的波段选择方法,它计算某波长点光谱数据对待测组分浓度向量的影响时,考虑了该波长点光谱数据的变化量与光谱PLS回归系数向量在该波长点的投影分量的共同影响。与传统相关系数方法想比较,该方法明显地改善了分析模型的稳健性并大幅度地压缩了建模所需的波长点数。对208个汽油样本的实验表明,经过PLS投影相关系数方法进行光谱波段选择后的光谱波长点数占全谱的比例下降至30%,交互验证均方根偏差(root mean square error of cross validation,RMSECV)由未经过波长选择时的0.44降至0.34。该方法可广泛应用于各类光谱定量分析中的波长选择与数据压缩。

CdZnTe晶体中微米级富Te相与PL谱的对应关系

采用红外透过显微镜(IRTM)观察了不同条件下生长的CdZnTe晶体中微米级富Te颗粒.结合实际生长条件分析了不同富Te颗粒的产生以及形态演化.通过低温光致发光(PL)谱研究了CdZnTe晶体中杂质、缺陷的状态,以及晶体的结晶质量,并测试了相应晶体的电阻率.归纳出不同富Te颗粒的产生与对应晶体10 K温度下PL谱中特征发光峰之间的关系.研究表明:富Te条件下生长的晶体存在圆形、六边形以及三角形富Te颗粒,PL谱中(D0,X)峰强度占主导;按化学计量比生长的晶体存在十字交叉的富Te颗粒,PL谱中DAP峰强度占主导;Cd过量生长的晶体存在星形富Te颗粒,PL谱中(D0,X)半峰宽较宽.