铋化物发光玻璃中银表面等离激元对铒离子的发光增强作用

局域表面等离激元可以由自由空间的光直接激发,这也是局域表面等离激元的优点所在。研究铋化物发光玻璃中纳米银颗粒的表面等离激元对铒离子发光的增强效应、进一步的提高铋化物发光玻璃中铒离子的发光性能很有意义。首先,测量了(A)Er 3+(0.5%)Ag(0.5%):铋化物发光玻璃与(B)Er 3+(0.5%):铋化物发光玻璃样品的吸收谱,发现(A)Er 3+(0.5%)Ag(0.5%):铋化物发光玻璃在约600.0 nm处有一个较弱的宽的银表面等离激元共振吸收峰。同时发现两者都有典型的铒离子的吸收峰,它们的吸收几乎完全一样:在波峰形状、峰值强度和峰值波长等方面都很相近。测量了(A)Er 3+(0.5%)Ag(0.5%):铋化物发光玻璃和(B)Er 3+(0.5%):铋化物发光玻璃样品的激发谱,发现有位于379.0,406.0,451.0,488.0和520.5 nm的5个550.0 nm可见光的可见激发谱峰,和位于379.0,406.5,451.0,488.5,520.5,544.0,651.5和798.0 nm的8个1531.0 nm红外光的红外激发谱峰,容易指认出依次为Er 3+的4I 15/2→4G 11/2,4I 15/2→2H 9/2,4I 15/2→(4F 3/2,4F 5/2),4I 15/2→4F 7/2,4I 15/2→2H 11/2,4I 15/2→4S 3/2,4I 15/2→4F 9/2和4I 15/2→4I 9/2跃迁的吸收峰,通过测量发现(A)Er 3+(0.5%)Ag(0.5%):铋化物发光玻璃相对于(B)Er 3+(0.5%):铋化物发光玻璃样品的可见和红外激发谱的最大增强依次分别是238%和133%。最后,测量了它们的发光谱,发现有位于534.0,547.5和658.5 nm的三组可见发光峰,容易指认出依次为Er 3+的2H 11/2→4I 15/2,4S 3/2→4I 15/2,4F 9/2→4I 15/2荧光跃迁。还发现红外发光峰位于978.0和1531.0 nm,依次为Er 3+的4I 11/2→4I 15/2和4I 13/2→4I 15/2的荧光跃迁。通过测量发现(A)Er 3+(0.5%)Ag(0.5%):铋化物发光玻璃相对于(B)Er 3+(0.5%):铋化物发光玻璃样品的可见和红外发光谱的最大增强依次分别是215%和138%。对于银表面等离激元增强铒离子发光的机理,认为主要为纳米银颗粒的局域表面等离激元共振,造成金属纳米结构附近产生的局域电场的强度要远大于入射光的电场强度,从而导致了金属纳米结构对入射光产生强烈的吸收和散射,进而导致了荧光的增强;即局域表面等离子体共振局域场的场增强效应。     

含纳米晶颗粒的Yb3+/Er3+共掺透明碲酸盐玻璃陶瓷的光谱性质研究

在组成为15Li2O-15Nb2O5-70TeO2-0.1Er2O3-0.4Yb2O3（%, 摩尔分数）的碲酸盐玻璃基础上, 采用两步热处理法制备了透明的含纳米晶颗粒碲酸盐玻璃陶瓷. 通过X射线衍射（XRD）测试表明, 玻璃陶瓷中的晶体颗粒组成为Yb6Te5O19.2或Er6Te5O19.2, 晶粒尺寸约为55 nm. 根据Judd-Ofelt理论计算了Er^3＋离子在基质玻璃和玻璃陶瓷中的光谱参数Ωt（t＝2, 4, 6）以及Er^3＋：4I15/2→4I13/2跃迁自发辐射几率, 根据McCumber理论计算了Er^3＋：4I13/2→4I15/2跃迁的发射截面. 测试了基质玻璃和玻璃陶瓷的拉曼光谱, 对比研究了铒离子在基质玻璃和玻璃陶瓷中1.5 μm处荧光和上转换光谱特性.     

基于线粒体co I 基因探讨无尾目10个科的分子系统关系

运用PCR技术和相关生物软件，对大头蛙Limnonectes kuhlii和脆皮大头蛙Limnonectes fragilis的线粒体coⅠ基因全序列进行了测定与分析．结合GenBank上已公布的无尾目10个科22个物种的同源序列，以爬行纲楔齿蜥Sphenodon punctatus和密河鳄Alligator mississippiensis为外群，基于核苷酸序列（选取前两位密码子）和氨基酸序列两种数据形式，分别构建NJ树和MP树．结果表明：系统树将无尾目10个科分为两大支，一支为新蛙亚目Neobatrachia的5科15个物种，一支为古蛙亚目Archaeobatrachia的5个科9个物种（其中包括锄足蟾科Pelobatidae和负子蟾科Pipidae），并推测这两个亚目均为单系群．古蛙亚目一支内的盘舌蟾科Discoglossidae与铃蟾科Bombinatoridae亲缘关系较近；新蛙亚目内蟾蜍科Bufonidae与雨蛙科Hylidae，蛙科Ranidae与树蛙科Rhacophoridae两两亲缘关系较近．蛙科中泽陆蛙Fejervarya limnocharis与大头蛙属3个种首先形成姐妹群，表明其较近的亲缘关系，同时推断大头蛙与福建大头蛙Limnonectes fujianensis亲缘关系近于脆皮大头蛙．     

Physical Properties of Novel Lead-Bismuthate Glasses with Large Transmitting Windows

Novel lead-bismuthate glasses with low OH concentration have been obtained in the Bi2O3-PbO-SrO system. The role of the different components in the glass formation has been explored from the density, refractive index measurements, indicating that the physical properties are mainly agected by Bi2O3 and PbO contents. The densities and refractive indices of these glasses are in the ranges of 7.639-7.699 g/cm^3 and 2.47-2.94, respectively. A wide transmitting window from visible to infrared (IR) regions and good thermal stability for some compositions of these g/asses have been observed, which make them appealing candidates for different optical applications suc has upconverting phosphors, new laser materials, optical waveguides and crystal-free fibre drawing.     

荧光捕获效应对Yb3+磷酸盐玻璃光谱性质的影响

测试了不同掺杂浓度和不同厚度下Yb³⁺磷酸盐玻璃的吸收光谱、荧光光谱和荧 光寿命，计算了积分吸收截面、吸收截面、受激发射截面、自发辐射寿命以及荧光有效线宽等光谱参数，讨论了荧光俘获效应对Yb³⁺磷酸盐玻璃光谱性质的影响.结果表明荧光俘 获效应随样品厚度和掺杂浓度的增加而增大.由于荧光俘获效应的存在使得测量的Yb^{3+磷酸盐玻璃荧光寿命明显长于计算的荧光寿命，在0.2mol%Yb₂O₃低掺 杂浓度下 关键词： 荧光俘获 掺镱磷酸盐玻璃 荧光光谱}     

Spectroscopic properties of Er~(3+)-doped AlF_3-La_2O_3-Al_2O_3-SiO_2 glasses

Er~(3+)-doped fluoride lanthanum aluminosilicate glasses with compositions of (65-x/2)SiO_2·(25-x/2)Al_2O_3·xAlF_3·9.1La_2O_3·0.6Er_2O_3·0.3Yb_2O_3(x=4, 8, 12, 20, 30) (mol%) were prepared and their glass transition temperatures and spectroscopic properties were investigated.The Ω_2, Ω_4, and Ω_6 intensity parameters of glasses were calculated by Judd-Ofelt theory from absorption curves. It was found that glasses transition temperature and melting temperature decreased with the increase of fluoride content in glass,Ω_2 decreased gradually with the increase of AlF_3 content,but both Ω_4 and Ω_6 did not increase until AlF_3 content increased to 30 mol%.The quantum efficiency of ~4I_(13/2) to ~4I_(15/2) transition of Er~(3+) ions increases with the increase of AlF_3 content in glass.Fluorescent lifetime is longer in glass containing more AlF_3 content.     

Visible Upconversion Emission in Er3＋—Doped GeO2—PbO—PbF2 Glass

The upconversion fluorescence emission of Er3 -doped 60GeO2-2OPbO-2OPbF2 glass was experimentally investigated under the pump of 976-nm laser diode. The results reveal the existence of intense emission bands centred around 524, 545, and 657nm at room temperature. The green emission at 524 and 545nm is due to the 4S3/2 2 Hll/2→ 4I15/2 transition and the red emission of 657nm originates from the 4F9/2-→4I15/2 transition of Er3 . The quadratic dependence of the green and red emissions on excitation power indicates that a two-photonabsorption process occurs under the 976-nm excitation. The excited- state absorption from 4I ll/2 and the cross relaxation between two Er3 ions in the 4I ll/2 state contribute to the green emission. The red emission at 657nm is attributed to the excited-state absorption and cross relaxation processes in the 4I13/2 level as well as the 4S3/2 level nonradiative transition of Er3 .     

Study of refractive index and thickness of TiO2／ormosil planar waveguide

Hybrid titania/ormosil waveguide films have been prepared by sol-gel method at low thermal treatment temperature of 150℃. The influence of processing parameters including the molar ratios of Ti(OBu)_{4}/glycidoxypropyltrimethoxysilane (GLYMO) and H_{2}O/Ti(OBu)_{4} (expressed as R), especially aging of sol, on the refractive index and thickness of film was investigated. The optical properties of films were measured with Scanning Electron Microscope and m-line spectroscopy. The results indicate that the film thickness increases with the aging time of sol, but the variation of refractive index as a function of aging time of sol depends on the relative ratio of GLYMO to Ti-alkoxide. The relation between film thickness and corresponding sol viscosity is linear as the volume of GLYMO is 80% within the range of measured data.     

Blue Upconversion Luminescence in Tm^3＋／Yb^3＋-Codoped Lead Chloride Tellurite Glass

The upconversion properties of Tm^3 /Yb3 -codoped lead chloride tellurite glass under 980hm excitation were investigated. The intense blue (476nm) emission and weak red (649 nm) emission corresponding to the ^1G4→4 ^3H6 and ^1G4→^3H4 transitions of Tm^3 ions, respectively, were simultaneously observed at room temperature. The dependence of upconversion intensities on excitation power and the possible upconversion mechanisms are evaluated. The intense blue upconversion luminescence of Tm^3 /Yb^3 -codoped lead chloride tellurite glass can be used as potential host material for the development of blue upconversion optical devices.     

Evaluation of Spectroscopic Properties of Yb^3＋ in Silicate—Based Heavy Metal Oxide Glasses

The absorption,stimulated emission cross section and potential laser parameters of heavy metal silicate glasses doped with Yb^3 ions have been investigated.The emission cross section has been evaluated by using the measured absoprtion spectra and principle of reciprocity.It is found that Yb^3 in SiO2-Bi2O3-B2O3 glass has high stimulated emission cross section of 0.09pm^2 for the 2F5/1→2F7/2 transition and exists short measured fluorescence lifetime of 0.78ms.On the other hand,the stimulated emission cross section of Yb^3 -doped SiO2-PbO glass was 0.49pm^2,Its measured fluorescence lifetime was 2.00ms.Evaluated from the good potential laser parameters,Yb^3 -doped SiO2-PbO glass may be a good candidate for fibre laser applications.