Nd AO_W.H. LeiOptical evaluation on Nd3+-doped phosphate glasses for O-band amplification

第15卷　第6期 强激光与粒子束Vol.15,No.6 2003年6月 HIGH POWER LASER AND PAR TICL E B EAMS J un.,2003　文章编号:　100124322(2003)0620538205高反射膜激光零几率损伤阈值的实验研究Ξ刘　强1,　林理彬1,　甘荣兵1,　唐方元1,　扎西次仁1,2(1.四川大学物理系,四川成都610064;　2.西藏大学数理系,西藏拉萨850000) 摘　要:　在确定光学薄膜激光损伤阈值的实验数据处理过程中,发现一些样品的数据点分布偏离直线型式。

对此,用国际标准规定的零几率来确定损伤阈值的同时,对测试数据点采用了不同的非直线拟合,也得到一个零几率损伤阈值。

比较两者差异,并与实验测试结果对照,发现这些样品采用非直线拟合得出的零几率损伤阈值与实际情况更接近一些。

关键词:　镀膜;　测试;　拟合方式;　零几率损伤阈值;　阈值比较 中图分类号:　TN24 文献标识码:　A 在高功率激光系统中,需要具有不同功能的光学元件,如高反镜、增透镜等。

这就需要在元件基片上镀以不同的介质薄膜,以提高或改善光学元件的性能。

在实验中发现,光学元件的激光损伤(尤其是光学膜层的激光损伤)限制了激光系统输出的最大功率。

因此,为了提高和评价光学元件的抗激光损伤能力,光学元件的激光损伤机理研究和激光损伤阈值的测定已成为惯性约束核聚变研究中的重要课题之一,研究人员给予了广泛关注并做了大量研究,取得了许多成果。

人们对激光阈值的测试方法进行了大量研究,包括显微观测法、光热光声法、扫描电镜法、干涉法、全息探测法、等离子体闪光法、雾气法[1]、散射光法[1,2]和透射反射法[3]等等。

相对说来,对实验数据的处理(处理方法不同,直接影响阈值确定)研究的很少。

比如,对同一类样品,各实验者所测定的损伤阈值之间的可比性差。

确定零损伤阈值的国际标准颁布后,这种状况有了较大改善。

然而,由于受众多因素的影响,即使按规定的测试方法对同一类样品进行测试,不同实验室测出的阈值结果仍有一定差异,对此有待深入研究。

3B SCIENTIFIC® PHYSICSBasic Experiments in Optics on the Optical Bench U17145Instruction sheet05/11/ALF/MEC1. Overview of the Experiments Experiment 1: Demonstration of the various raybeamsExperiment 2: Reflection of a ray of light from aplane mirrorExperiment 3: Reflection of a light beam from aplane mirrorExperiment 4: Reflection of a light beam from aconcave or convex mirror Experiment 5: Snell's law of refraction Experiment 6: Refraction of light through aplaneparallel plateExperiment 7: Refraction of light through aprismExperiment 8: Inverting prismsExperiment 9: Concave and convex lenses2. Scope of delivery1 Optical bench U, 120 cm (U17150)3 Optical rider U, 75 mm (U17160)1 Optical rider U, 30 mm (U17161)1 Experiment lamp, halogen (U17140)1 Spare lamp, halogen 12 V, 50 W (U13735)1 Object holder on a stem (U8474000)1 Convexlens,f = + 150 mm; 50 mm Ø (U17103)1 Set of slits and apertures (U17040)1 Optical disc with accessories (U17128)1 Storage strip (U17120)3. Safety instructions•Warning! Lamps become extremely hot when operated for prolonged periods of time.•Do not clean any of the optical components with aggressive fluids or solvents. This could cause damage!4. Experiment examples Experiment 1: Demonstration of various raybeams1.1 Equipment1 Opticalbench1 Experimentallamp1 Object holder, shaft-mounted1 Fivefold slit from U170401 Convexlensf = +150 mm3 Optical riders 75 mm1 Optical rider 30 mmAdditionally required:1 TransformerU139001 Projection screen U171301.2 Set up•Place the experimental lamp horizontally on the rail at the 10 cm position.•Place the object holder with five-fold slit hori-zontally on the rail at the 20 cm position. •Place the convex lens at the 25 cm position. •Mount the projection screen on the small rider.1.3 Procedure•When the convex lens is not used, the ray beam is divergent.•When the convex lens is placed at the 25 cm position we obtain a parallel beam of rays. •When the convex lens is moved away from the light source a converging beam of rays is pro-duced.Experiment 2: Reflection of a ray of light froma plane mirror2.1 Equipment1 Opticalbench1 Experimentallamp1 Object holder, shaft mounted1 Diaphragm with single slit from U170401 Convexlensf = +150 mm1 Optical disc1 Plane mirror from U171283 Optical riders 75 mm1 Optical rider 30 mmAdditionally required:1 TransformerU139002.2 Set up•Place the experimental lamp horizontally on the rail at the 10 cm position.•Place the object holder with single-slit dia-phragm horizontally on the rail at the 20 cm position.•Place the concave lens at the 25 cm position. •Mount the optical disc with plane mirror on a small optical rider at the 40 cm position.2.3 Procedure•Fasten the plane mirror mounted on the opti-cal disc to the 90° to -90° line.•Set the height of the disc so that the incident light ray is reflected from the 0° line.•By rotating the disc we can verify the law of reflection, which states that the angle of inci-dence is equal to the angle of reflection.Experiment 3: Reflection of a light beam froma plane mirror3.1 Equipment1 Opticalbench1 Experimentallamp1 Object holder, shaft mounted1 Fivefold slit from U170401 Convexlensf = +150 mm1 Optical disc1 Plane mirror from U171283 Optical riders 75 mm1 Optical rider 30 mmAdditionally required:1 TransformerU139003.2 Set up•Place the experimental lamp horizontally on the rail at the 10 cm position..•Place the object holder with the five-fold slit at the 20 cm position.•Place the convex lens at the 25 cm position. •Mount the optical disc with plane mirror on a small optical rider at the 40 cm position.3.3 Procedure•Attach the plane mirror on the optical disc at the 90°-90° line.•Adjust the height of the disc so that the middle ray of light propagates along the 0° line and all rays are reflected into each other.•By rotating the disc it is demonstrated that a parallel incident beam of light is also parallel after being reflected.•By moving the lens away from the light source it can be demonstrated that a converging light beam is also reflected as a converging light beam.•Without the use of the convex lens it can be demonstrated that a divergent light beam also diverges upon reflection.Experiment 4: Reflection of a light beam froma concave or convex mirror4.1 Equipment1 Opticalbench1 Experimentallamp1 Object holder, shaft mounted1 Fivefold slit from U170401 Convexlensf = +150 mm1 Optical disc1 Plane mirror from U171283 Optical riders 75 mm1 Optical rider 30 mmAdditionally required:1 TransformerU139004.2 Set up•Place the experimental lamp horizontally on the rail at the 10 cm position.•Place the object holder with five-fold slit hori-zontally on the rail at the 20 cm position. •Place the convex lens at the 25 cm position. •Place the optical disc with convex mirror on the small rider at the 40 cm position.4.3 Procedure•Fasten the concave mirror on the optical disc on the 90°-90° line.•Adjust the height of the disc so that the middle ray of light travels along the 0° line and is re-flected into itself.•Use the lens to generate a parallel beam. •The incidenting rays are reflected so that they all pass through and converge at a single pointF. This point is the focal point of the mirror. •Repeat the experiment with converging and diverging light beams.•Result: a concave mirror causes the rays to converge.•Rotate the optical disc by 180° so that the incident rays are reflected by the convex mir-ror. Carry out the same procedural steps as stated above.• A convex mirror causes the rays to diverge.Experiment 5: Snell's law of refraction5.1 Equipment1 Opticalbench1 Experimentallamp1 Object holder, shaft mounted1 Diaphragm with single slit from U170401 Convexlensf = +150 mm1 Optical disc1 Semi-circular body from U171283 Optical riders 75 mm1 Optical rider 30 mmAdditionally required:1 TransformerU139005.2 Set up•Place the experimental lamp horizontally on the rail at the 10 cm position.•Place the object holder with single slot dia-phragm horizontally on the rail at the 20 cmposition.•Place the concave lens at the 25 cm position. •Mount the optical disc with semi-circular body on the small rider at the 40 cm position.5.3 Procedure•Fasten the semi-circular body on the optical disc on the 90°-90° line so that the plane sideis facing the light source.•Adjust the height of the disc so that the inci-denting light ray propagates along the 0° lineand is incident at the precise center of thesemicircular body. The ray of light then propa-gates uninterrupted along the 0° line.•When the disc is rotated, the light ray is re-fracted toward the normal at the point of inci-dence.•The disc is now rotated by 180° so that the convex disc is facing the light source. The lightray is now refracted away from the normal atthe point of incidence.βn n•When the light ray passes from one medium with the refractive index n 1 to another medium with the refractive index n 2 its directional change is determined by Snell's law of refrac-tion:sin sin α=βconstant or12sin sin n n α=β • α is the angle of incidence in medium n 1 and β is the angle of refraction in medium n 2.•The bigger the angle of incidence is, the larger the angle of refraction becomes. I f n 1 < n 2, there is a critical angle α. At this angle the re-fracted ray of light is refracted along the inter-face between two media. I f the angle of inci-dence is greater than the critical angle, then there is no longer any refraction and all light is reflected. This case is referred to as total inter-nal reflection.Experiment 6: Refraction in a plane-parallelplate6.1 Equipment 1 Optical bench 1 Experimental lamp 1 Object holder, shaft mounted 1 Diaphragm with single slit from U17040 1 Convex lens f = +150 mm 1 Optical disc 1 Trapezoidal body from U17128 3 Optical riders 75 mm 1 Optical rider 30 mm Additionally required: 1 Transformer U139006.2 Set up• Place the experimental lamp horizontally onthe rail at the 5 cm position.• Set up the object holder including diaphragmwith single slit at the 20 cm position.• Place the concave lens at the 25 cm position. • Set up the optical disc with trapezoidal bodyon the small optical rider at the 40 cm posi-tion.6.3 Procedure• Fasten the trapezoidal body on the optical discalong the 90° to -90° line so that its long side faces the light source. The middle section of the trapezoidal body acts like a plane-parallel plate.• Adjust the height of the disc so that the inci-denting light beam propagates on the 0° line and is not refracted by the trapezoidal body. • Rotate the disc so that the beam is now re-fracted.• The direction of the outgoing light ray is notaltered.• The outgoing light ray is nevertheless divertedfrom its original path by a distance d . For a plate of h density, this gives the following ford : sin()cos d h α−β=⋅βExperiment 7: Refraction at a prism7.1 Equipment 1 Optical bench 1 Experimental lamp 1 Object holder, shaft mounted 1 Diaphragm with single slit from U17040 1 Convex lens f = +150 mm 1 Optical disc 1 Trapezoidal body from U17128 1 Right-angled prism from U17128 3 Optical riders 75 mm 1 Optical rider 30 mm Additionally required: 1 Transformer U139007.2 Set up•Place the experimental lamp at the 5 cm posi-tion.•Set up the object holder with diaphragm in-cluding single slit at the 20 cm position. •Place the concave lens at the 25 cm position. •Set the optical disc with trapezoidal body on the small optical rider at the 40 cm position.7.3 Procedure•Fasten the trapezoidal body onto the optical disc along the 90° to -90° line so that the pyramid points upwards.•Adjust the height of the disc so that the inci-dent light ray travels on the 0° line.•After the disc is rotated, the light ray incidents on the upper section of the trapezoidal body, which now functions, like a prism.•n an acrylic prism the light ray incident at point A is refracted from the axis of incidence.At the emerging point B the ray is refracted away from the axis of incidence. The sum total of all refraction angles is called the deflection angle δ. This is the angle between the incident and emerging light rays.•It can be demonstrated that the incident angle α at the minimum deflection angle δminis equal to the emerging angle β. The refracted ray then propagates inside the prism parallel to the side, which is not passed through.Experiment 8: Inverting prisms8.1 Equipment1 Opticalbench1 Experimentallamp1 Object holder, shaft mounted1 Diaphragm with single and fivefold slit from 1 Convexlensf = +150 mm1 Optical disc1 Right-angled prism from U171283 Optical riders 75 mm1 Optical rider 30 mmAdditionally required:1 TransformerU13900 8.2 Set up•Place the experimental lamp horizontally on the rail at the 5 cm position.•Place the object holder including a diaphragm with single or five-fold slot horizontally on rail at the 20 cm position.•Set up the concave lens at the 25 cm position. •Set the optical disc with right-angled prism on the small optical rider at the 40 cm position.8.3 Procedure•Fasten the right-angled prism on the optical disc along the 90°-90° line so that the right an-gle is lined up with the 0° line and faces the light source.•Adjust the height of the disc so that the inci-dent light beam propagates on the 0° line. •By rotating the disc all of the previously de-scribed phenomena can be observed.•At a certain angle (limiting angle) the ray is subject to total internal reflection.•Using the diaphragm with fivefold slit, it can be demonstrated that the rays can be reflected back in the direction from which they came.1231’2’3’1233’2’1’3B Scientific GmbH • Rudorffweg 8 • 21031 Hamburg • Germany • Subject to technical amendments Experiment 9: Concave and convex lenses9.1 Equipment 1 Optical bench 1 Experimental lamp 1 Object holder shaft-mounted 1 Diaphragm with fivefold slit from U17040 1 Concave lens f = +150 mm 1 Optical disc Lenses from U17128 3 Optical riders 75 mm 1 Optical riders 30 mm Additionally required: 1 Transformer U139009.2 Set up• Place the experimental lamp horizontally onthe rail at the 10 cm position.• Set the object holder up with fivefold slit hori-zontally on the rail at the 22 cm position. • Place the concave lens at the 27 cm position. • Set up the optical disc with lens on the smalloptical rider.9.3 Procedure• Place the convex lens in a central position onthe optical disc.• Adjust the height of the disc so that the centerof the incident light beam propagates on the 0° line.• A convex lens is a converging lens. After pass-ing through the medium the light rays all con-verge at the focal point F.• Repeat the experiment using the concave lens. • The light rays diverge after passing through thelens. No image of an object emerges. Tracing the divergent rays backwards one arrives at a virtual focal F ' where these lines meet.。

Au纳米粒子增强丙酮受激拉曼散射研究梁慧敏;王景全;侯宜栋;吴轩楠【摘要】受激拉曼散射(stimulated Raman scattering,SRS)具有激光的特性,并且容易获取不同波长的激光,从而成为调谐激光频率的重要途径之一.然而,由于其转化效率低,限制了它的实际应用.金属纳米粒子具有很强的表面增强效应,曾被广泛地用于增强拉曼散射而获得良好的效果.本文提出将金属纳米粒子的这种性质用于增强SRS.把Au纳米粒子混合于拉曼介质丙酮中,以532 nm的纳秒脉冲激光作为激发光,研究了Au纳米粒子在丙酮中的浓度对丙酮SRS一阶Stokes光强的影响,并通过仿真计算对实验结果进行了解释和分析.【期刊名称】《光散射学报》【年(卷),期】2016(028)004【总页数】4页(P308-311)【关键词】受激拉曼散射;金属纳米粒子;表面增强【作者】梁慧敏;王景全;侯宜栋;吴轩楠【作者单位】河北工程大学理学院,邯郸056038;河北工程大学理学院,邯郸056038;四川大学物理科学与技术学院,成都610064;四川大学物理科学与技术学院,成都610064【正文语种】中文【中图分类】O437.3受激拉曼散射(stimulated Raman scattering,SRS)调谐激光具有线宽和脉宽狭窄、装备简单、操作简便、价格低廉等优点,是脉冲激光调谐技术的重要途径之一,因而成为国内外学者研究的热点[1-4]。

但是,由于其转化效率较低,在一定程度上限制了它的实际应用。

因此,多种提高其转化效率的方法相继被提出。

典型的方法有荧光增强[5-7]、选择高增益的拉曼介质[8-10]、设计腔结构[11-14]等,这些方法使SRS Stokes光得到增强,转化效率在一定程度上得到了提高。

金属纳米粒子的表面等离子体(surface plasmon polariton,SPP)增强效应被广泛地用于增强拉曼散射[15-18],并获得非常理想的增强效果,有些情况下可使拉曼散射光增强高达约106倍甚至更高[16,18]。

文章编号 2097-1842（2023）06-1305-13氮化镓基Micro-LED 侧壁对外量子效率的影响及侧壁处理技术综述邝　海*，黄　振，熊志华，刘　丽（江西科技师范大学 江西省光电子与通信重点实验室, 江西 南昌 330038）摘要：氮化镓基Micro-LED 具备高亮度、高响应频率、低功耗等优点，是未来显示技术和可见光通信系统的理想选择，但是目前外量子效率（EQE ）低下这一问题严重影响其规模化量产及进一步应用。

为了突破EQE 低下这一瓶颈，通过分析Micro-LED 外量子效率的影响因素，得知EQE 下降的主要原因包括侧壁缺陷引起的载流子损耗及非辐射复合。

总结了侧壁缺陷对载流子输运及复合的影响。

综述了目前常用的侧壁处理技术及修复方法，指出现有侧壁处理方法较为笼统、针对性不足且载流子与侧壁缺陷的作用机理并不十分清楚。

提出应深入系统地研究侧壁缺陷种类和分布、载流子与侧壁缺陷作用机制及侧壁处理过程中的缺陷修复模式。

本文为提高外量子效率、加快Micro-LED 商业化量产进程提供设计思路和理论依据。

关 键 词：侧壁缺陷；微发光二极管；外量子效率；载流子；侧壁钝化中图分类号：TN312 文献标志码：A doi ：10.37188/CO.2023-0091A review of the effect of GaN-Based Micro-LED sidewall on externalquantum efficiency and sidewall treatment techniquesKUANG Hai *，HUANG Zhen ，XIONG Zhi-hua ，LIU Li（Key Laboratory for Optoelectronics and Communication of Jiangxi Province ,Jiangxi Science Technology Normal University , Nanchang 330038, China ）* Corresponding author ，E-mail : haizi 411@Abstract : Micro-LEDs offers the benefits of high brightness, high response frequency, and low power con-sumption, making them an attractive candidate for future display technologies and Visible Light Communica-tion (VLC) systems. Nonetheless, their low External Quantum Efficiency (EQE) currently impedes their scaled mass production and further applications. In order to break through the bottleneck of low EQE, we conducted an analysis of Micro-LED external quantum efficiency’s contributing factors. The influencing收稿日期：2023-05-15；修订日期：2023-06-02基金项目：江西省教育厅科学技术研究项目（No. GJJ2201338)；国家自然科学基金（No. 12364013)；江西科技师范大学博士科研启动基金项目（No.2019BSQD020)；中央引导地方科技发展资金项目（No. 2022ZDD03088)Supported by Science and Technology Research Project of Jiangxi Education Department (No. GJJ2201338);National Natural Science Foundation of China (No. 12364013); Doctoral Research Foundation of Jiangxi Sci-ence and Technology Normal University (No. 2019BSQD020); Government Guides Local Science and Techno-logy Development Funds(No. 2022ZDD03088)第 16 卷　第 6 期中国光学（中英文）Vol. 16　No. 62023年11月Chinese OpticsNov. 2023factors for EQE are analyzed. It is concluded that the carrier loss and non-radiative recombination caused by sidewall defects are the main reasons for the decrease in EQE. In addition, we summarized the impact of sidewall defects on carrier transport and composites, and we also reviewed the commonly used sidewall treat-ment technology and repair methods, and pointed out that the existing sidewall treatment methods are helpful but insufficient for improving EQE, and the mechanism of carrier interaction with sidewall defects is not very clear. It is suggested to carry out a thorough and systematic study on the types and distribution of sidewall de-fects, the mechanism of carrier and sidewall defects, and the defect repair mode in the sidewall treatment pro-cess. Finally, future development trends are projected. This paper offers design ideas and theoretical founda-tions to enhance the external quantum efficiency and accelerate the process of commercialization and mass production of Micro-LEDs.Key words: defects on sidewall；micro-LED；external quantum efficiency；carriers；surface passivation1 引　言微发光二极管（Micro-Light-Emitting diode，Micro-LED）因具有其他光源不可比拟的优势而备受关注[1-6]。

Preprint of:Timo A.Nieminen,Vincent L.Y.Loke,Alexander B.Stilgoe,Gregor Kn¨o ner,Agata M.Bra´n czyk,Norman R.Heckenberg and Halina Rubinsztein-Dunlop “Optical tweezers computational toolbox”Journal of Optics A9,S196-S203(2007)Optical tweezers computational toolboxTimo A Nieminen,Vincent L Y Loke,Alexander B Stilgoe,Gregor Kn¨o ner,Agata M Bra´n czyk,Norman R Heckenbergand Halina Rubinsztein-DunlopCentre for Biophotonics and Laser Science,School of Physical Sciences,TheUniversity of Queensland,Brisbane QLD4072,AustraliaAbstract.We describe a toolbox,implemented in Matlab,for the computationalmodelling of optical tweezers.The toolbox is designed for the calculation of opticalforces and torques,and can be used for both spherical and nonspherical particles,inboth Gaussian and other beams.The toolbox might also be useful for light scatteringusing either Lorenz–Mie theory or the T-matrix method.1.IntroductionComputational modelling provides an important bridge between theory and experiment—apart from the simplest cases,computational methods must be used to obtain quantitative results from theory for comparison with experimental results. This is very much the case for optical trapping,where the size range of typical particles trapped and manipulated in optical tweezers occupies the gap between the geometric optics and Rayleigh scattering regimes,necessitating the application of electromagnetic theory.Although,in principle,the simplest cases—the trapping and manipulation of homogeneous and isotropic microspheres—has an analytical solution—generalised Lorenz–Mie theory—significant computational effort is still required to obtain quantitative results.Unfortunately,the mathematical complexity of Lorenz–Mie theory presents a significant barrier to entry for the novice,and is likely to be a major contributor to the lagging of rigorous computational modelling of optical tweezers compared to experiment.If we further consider the calculation of optical forces and torques on non-spherical particles—for example,if we wish to consider optical torques on and rotational alignment of non-spherical microparticles,the mathematical difficulty is considerably greater.one the efficient methods for calculating optical forcesand torques on non-spherical particles in optical traps is closly allied to Lorenz–Mie theory—the T-matrix method(Waterman1971,Mishchenko1991,Nieminen et al.2003a).However,while the Mie scattering coefficients have a relatively simple analytical form,albeit involving special functions,the T-matrix requires considerable numerical effort for its calculation.It is not surprising that the comprehensive bibliographic database on computational light scattering using the T-matrix method by Mishchenko et al.(2004)lists only four papers applying the method to optical tweezers(Bayoudh et al.2003,Bishop et al.2003,Nieminen,Rubinsztein-Dunlop, Heckenberg&Bishop2001,Nieminen,Rubinsztein-Dunlop&Heckenberg2001).Since the compilation of this bibliography,other papers have appeared in which this is done (Nieminen et al.2004,Simpson&Hanna2007,Singer et al.2006),but they are few in number.Since the potential benefits of precise and accurate computational modelling of optical trapping is clear,both for spherical and non-spherical particles,we believe that the release of a freely-available computational toolbox will be valuable to the optical trapping community.We describe such a toolbox,implemented in Matlab.We outline the theory underlying the computational methods,the mathematics and the algorithms,the toolbox itself,typical usage,and present some example results.The toolbox can be obtained at .au/people/nieminen/software.html at the time of publication.Since such software projects tend to evolve over time,and we certainly intend that this one will do so,potential users are advised to check the accompanying documentation.Along these lines,we describe our plans for future development. Of course,we welcome input,feedback,and contributions from the optical trapping community.2.FundamentalsThe optical forces and torques that allow trapping and manipulation of microparticles in beams of light result from the transfer of momentum and angular momentum from the electromagneticfield to the particle—the particle alters the momentum or angular momentumflux of the beam through scattering.Thus,the problem of calculating optical forces and torques is essentially a problem of computational light scattering.In some ways,it is a simple problem:the incidentfield is monochromatic,there is usually only a single trapped particle,which isfinite in extent,and speeds are so much smaller than the speed of light that we can for most purposes neglect Doppler shifts and assume we have a steady-state monochromatic single-scattering problem.Although typical particles inconveniently are of sizes lying within the gap between the regimes of applicability of small-particle approximations(Rayleigh scattering) and large-particle approximations(geometric optics),the particles of choice are often homogeneous isotropic spheres,for which an analytical solution to the scattering problem is available—the Lorenz–Mie solution(Lorenz1890,Mie1908).While theapplication of Lorenz–Mie theory requires significant computational effort,the methods are well-known.The greatest difficulty encountered results from the incident beam being a tightly focussed beam.The was developed for scattering of plane waves,and its extension to non-plane illumination is usually called generalised Lorenz–Mie theory(GLMT)(Gouesbet&Grehan1982)which has seen significant use for modelling the optical trapping of homogeneous isotropic spheres(Ren et al.1996, Wohland et al.1996,Maia Neto&Nussenzweig2000,Mazolli et al.2003,Lock2004a, Lock2004b,Kn¨o ner et al.2006,Neves et al.2006).The same name is sometimes used for the extension of Lorenz–Mie theory to non-spherical,but still separable geometries such as spheroids(Han&Wu2001,Han et al.2003).The source of the difficulty lies in the usual paraxial representations of laser beams being solutions of the scalar paraxial wave equation rather than solutions of the vector Helmholtz equation.Our method of choice is to use a least-squaresfit to produce a Helmholtz beam with a far-field matching that expected from the incident beam being focussed by the objective(Nieminen et al.2003b).At this point,we can write the incidentfield in terms of a discrete basis set of functionsψ(inc)n,where n is mode index labelling the functions,each of which is a solution of the Helmholtz equation,U inc=∞n a nψ(inc)n,(1)where a n are the expansion coefficients for the incident wave.In practice,the sum must be truncated at somefinite n max,which places restrictions on the convergence behaviour of useful basis sets.A similar expansion is possible for the scattered wave,and we can writeU scat=∞k p kψ(scat)k,(2)where p k are the expansion coefficients for the scattered wave.As long as the response of the scatterer—the trapped particle in this case—is linear, the relation between the incident and scatteredfields must be linear,and can be written as a simple matrix equationp k=∞n T kn a n(3)or,in more concise notation,P=TA(4) where T kn are the elements of the T-matrix.This is the foundation of both GLMT and the T-matrix method.In GLMT,the T-matrix T is diagonal,whereas for non-spherical particles,it is not.When the scatterer isfinite and compact,the most useful set of basis functions is vector spherical wavefunctions(VSWFs)(Waterman1971,Mishchenko1991,Nieminenet al.2003a,Nieminen et al.2003b).Since the VSWFs are a discrete basis,this method lends itself well to representation of thefields on a digital computer,especially since their convergence is well-behaved and known(Brock2001).The T-matrix depends only on the properties of the particle—its composition, size,shape,and orientation—and the wavelength,and is otherwise independent of the incidentfield.This means that for any particular particle,the T-matrix only needs to be calculated once,and can then be used for repeated calculations of optical force and torque.This is the key point that makes this a highly attractive method for modelling optical trapping and micromanipulation,since we are typically interested in the optical force and torque as a function of position within the trap,even if we are merely trying to find the equilibrium position and orientation within the trap.Thus,calculations must be performed for varying incident illumination,which can be done very easily with the T-matrix method.This provides a significant advantage over many other methods of calculating scattering where the entire calculation needs to be repeated.This is perhaps the the reason that while optical forces and torques have been successfully modelled using methods such as thefinite-difference time-domain method(FDTD),the finite element method(FEM),or other methods(White2000b,White2000a,Hoekstra et al.2001,Collett et al.2003,Gauthier2005,Chaumet et al.2005,Sun et al.2006,Wong &Ratner2006),the practical application of such work has been limited.Since,as noted above,the optical forces and torques result from differences between the incoming and outgoingfluxes of electromagnetic momentum and angular momentum,calculation of thesefluxes is required.This can be done by integration of the Maxwell stress tensor,and its moment for the torque,a surface surrounding the particle.Fortunately,in the T-matrix method,the bulk of this integral can be performed analytically,exploiting the orthogonality properties of the VSWFs.In this way,the calculation can be reduced to sums of products of the expansion coefficients of thefields.At this point,two controversies in macroscopic classical electromagnetic theory intrude.Thefirst of these is the Abraham–Minkowski controversy,concerning the momentum of an electromagnetic wave in a material medium(Minkowski1908, Abraham1909,Abraham1910,Jackson1999,Pfeifer et al.2006).This controversy is resolved for practical purposes by the realisation that what is physically observable is not the force due to change in the electromagnetic momentum,but the force due to the total momentum.The controversy is essentially one of semantics—what portion of the total momentum is to be labelled“electromagnetic”,and what portion is to be labelled “material”(Pfeifer et al.2006).Abraham’s approach can be summarised as calling P/nc the electromagnetic momentumflux,where P is the power,n the refractive index,and c the speed of light in free The quantum equivalent is the momentum of a photon in a material medium¯h k/n2=¯h0on the other hand,gives nP/c as the electromagneticflux,or¯h k=n¯h k0photon.The discrepancy is resolved by realising that the wave of induced polarisation in the dielectric carries energy and momentum,equal to the difference between the Abraham and Minkowskipictures.It is simplest to use the Minkowski momentum flux nP/c ,since this is equal to the total momentum flux.The second controversy is the angular momentum density of circularly polarised electromagnetic waves (Humblet 1943,Khrapko 2001,Zambrini &Barnett 2005,Stewart 2005,Pfeifer et al.2006).On the one hand,we can begin with theassumption that the angular momentum density is the moment of the momentum density,r ×(E /c ,which results in a circularly polarised plane wave carrying zero angular momentum in the direction of propagation.On the other hand,we can begin with the Lagrangian for an electromagnetic radiation field,and obtain the canonical stress tensor and an angular momentum tensor that can be divided into spin and orbital components (Jauch &Rohrlich 1976).For a circularly polarised plane wave,the component of the angular momentum flux in the direction of propagation would be I/ω,where I is the irradiance and ωthe angular frequency,in disagreement with the first result.The division of the angular momentum density resulting from this procedure is not gauge-invariant,and it is common to transform the integral of the angular momentum density into a gauge-invariant form,yielding the integral of r ×(E ×H )/c .Jauch &Rohrlich (1976)carefully point out that this transformation requires the dropping of surface terms at infinity.The reverse of this procedure,obtaining the spin and orbital term starting from r ×(E ×H )/c ,involving the same surface terms,had already been shown by Humblet (1943).The controversy thus consists of which of the two possible integrands to call the angular density.However,it is not the angular momentum density as such that we are interested in,but the total angular momentum flux through a spherical surface surrounding the particle.For the electromagnetic fields used in optical tweezers,this integrated flux is the same for both choices of angular momentum density.Crichton &Marston (2000)also show that for monochromatic radiation,the division into spin and orbital angular momenta is gauge-invariant,and observable,with it being possible to obtain the spin from measurement of the Stokes parameters.The total angular momentum flux is the same as that resulting from assuming a density of r ×(E ×H )/c .Since the torque due to spin is of practical interest (Nieminen,Heckenberg &Rubinsztein-Dunlop 2001,Bishop et al.2003,Bishop et al.2004),it is worthwhile to calculate this separately from the total torque.3.Incident fieldThe natural choice of coordinate system for optical tweezers is spherical coordinates centered on the trapped particle.Thus,the incoming and outgoing fields can be expanded in terms of incoming and outgoing vector (VSWFs):E in =∞ n =1n m =−n a nm M (2)nm (k r )+b nm N (2)nm (k r ),(5)E out =∞ n =1n m =−np nm M (1)nm (k r )+q nm N (1)nm (k r ).(6)where the VSWFs areM(1,2)nm (k r)=N n h(1,2)n(kr)C nm(θ,φ)(7)N(1,2)nm (k r)=h(1,2)n(kr)krN nP nm(θ,φ)+N n h(1,2)n−1(kr)−nh(1,2)n(kr)kr B nm(θ,φ)where h(1,2)n(kr)are spherical Hankel functions of thefirst and second kind,N n= [n(n+1)]−1/2are normalization constants,and B nm(θ,φ)=r∇Y m n(θ,φ),C nm(θ,φ)=∇×(r Y m n(θ,φ)),and P nm(θ,φ)=ˆr Y m n(θ,φ)are the vector spherical harmonics (Waterman1971,Mishchenko1991,Nieminen et al.2003a,Nieminen et al.2003b), and Y m n(θ,φ)are normalized scalar spherical harmonics.The usual polar spherical coordinates are used,whereθis the co-latitude measured from the+z axis,andφis the azimuth,measured from the+x axis towards the+y axis.M(1)nm and N(1)nm are outward-propagating TE and TM multipolefields,while M(2)nm and N(2)nm are the corresponding inward-propagating multipolefields.Since these wavefunctions are purely incoming and purely outgoing,each has a singularity at the origin.Sincefields that are free of singularities are of interest,it is useful to define the singularity-free regular vector spherical wavefunctions:RgM nm(k r)=1[M(1)nm(k r)+M(2)nm(k r)],(8)RgN nm(k r)=12[N(1)nm(k r)+N(2)nm(k r)].(9) Although it is usual to expand the incidentfield in terms of the regular VSWFs, and the scatteredfield in terms of outgoing VSWFs,this results in both the incident and scattered waves carrying momentum and angular momentum away from the system. Since we are primarily interested in the transport of momentum and angular momentum by thefields(and energy,too,if the particle is absorbing),we separate the totalfield into purely incoming and outgoing portions in order to calculate these.The user of the code can choose whether the incident–scattered or incoming–outgoing representation is used otherwise.We use an point-matching scheme tofind the expansion coefficients a nm and b nm describing the incident beam et al.2003b),providing stable and robust numerical performance and convergence.Finally,one needs to be able to calculate the force and torque for the same particle in the same trapping beam,but at different positions or orientations.The transformations of the VSWFs under rotation of the coordinate system or translation of the origin of the coordinate system are known(Brock2001,Videen2000,Gumerov& Duraiswami2003,Choi et al.1999).It is sufficient tofind the VSWF expansion of the incident beam for a single origin and orientation,and then use translations and rotations tofind the new VSWF expansions about other points(Nieminen et al.2003b,Doicu& Wriedt1997).Since the transformation matrices for rotation and translations along the z-axis are sparse,while the transformation matrices for arbitrary translations are full,the most efficient way to carry out an arbitrary translation is by a combination of rotation and axial translation.The transformation matrices for both rotations and axialtranslations can be efficiently computed using recursive methods(Videen2000,Gumerov &Duraiswami2003,Choi et al.1999).3.1.ImplementationFirstly,it is necessary to provide routines to calculate the special functions involved. These include:(i)sbesselj.m,sbesselh.m,sbesselh1.m,and sbesselh2.m for the calculation ofspherical Bessel and Hankel functions.These make use of the Matlab functions for cylindrical Bessel functions.(ii)spharm.m for scalar spherical harmonics and their angular partial derivatives. (iii)vsh.m for vector spherical harmonics.(iv)vswf.m for vector spherical wavefunctions.Secondly,routines must be provided tofind the expansion coefficients,or beam shape coefficients,a nm and b nm for the trapping beam.These are:(i)bsc pointmatch farfield.m and bsc pointmatch focalplane.m,described in(Nieminen et al.2003b),which can calculate the expansion coefficients for Gaussian beams,Laguerre–Gauss modes,and bi-Gaussian beams.Since these routines are much faster for rotationally symmetric beams,such as Laguerre–Gauss beams,a routine,lgmodes.m,that can provide the Laguerre–Gauss decomposition of an arbitrary paraxial beam is also provided.(ii)bsc plane.m,for the expansion coefficients of a plane wave.This is not especially useful for optical trapping,but makes the toolbox more versatile,improving its usability for more general light scattering calculations.Thirdly,the transformation matrices for the expansion coefficients under rotations and translations must be calculated.Routines include:(i)wigner rotation matrix.m,implementing the algorithm given by Choi et al.(1999).(ii)translate z.m,implementing the algorithm given by Videen(2000).4.T-matrixFor spherical particles,the usual Mie coefficients can be rapidly calculated.For non-spherical particles,a more intensive numerical effort is required.We use a least-squares overdetermined point-matching method(Nieminen et al.2003a).For axisymmetric particles,the method is relatively fast.However,as is common for many methods of calculating the T-matrix,particles cannot have extreme aspect ratios,and must be simple in shape.Typical particle shapes that we have used are spheroids and cylinders, and aspect ratios of up to4give good results.Although general non-axisymmetric particles can take a long time to calculate the T-matrix for,it is possible to makeuse of symmetries such as mirror symmetry and discrete rotational symmetry to greatly speed up the calculation (Kahnert 2005,Nieminen et al.2006).We include a symmetry-optimised T -matrix routine for cubes.Expanding the range of particles for which we can calculate the T -matrix is one of our current active research efforts,and we plan to include routines for anistropic and inhomogeneous particles,and particles with highly complex geometries.Once the T -matrix is calculated,the scattered field coefficients are simply found by a matrix–vector multiplication of the T -matrix and a vector of the incident field coefficients.4.1.ImplementationOur T -matrix routines include:(i)tmatrix mie.m ,calculating the Mie coefficients for homogeneous isotropic spheres.(ii)tmatrix pm.m ,our general point-matching T -matrix routine.(iii)tmatrix pm cube.m ,the symmetry-optimised cube code.5.Optical force and torqueAs noted earlier,the integrals of the momentum and angular momentum fluxes reduce to sums of products of the expansion coefficients.It is sufficient to give the formulae for the z -components of the fields,as given,for example,by Crichton &Marston (2000).We use the same formulae to calculate the x and y components of the optical force and torque,using 90◦rotations of the coordinate system (Choi et al.1999).It is also possible to directly calculate the x and y components using similar,but more complicated,formulae (Farsund &Felderhof 1996).The axial trapping efficiency Q isQ =2P ∞ n =1n m =−n m n (n +1)Re(a nm b nm −p nm q nm )−1n +1 n (n +2)(n −m +1)(n +m +1)(2n +1)(2n +3)12×Re(a nm a n +1,m +b nm b n +1,m−p nm p n +1,m −q nm q n +1,m )(10)in units of n ¯h k per photon,where n is the refractive index of the medium in which the trapped particles are suspended.This can be converted to SI units by multiplying by nP/c ,where P is the beam power and c is the speed of light in free space.The torque efficiency ,or normalized torque,about the z -axis acting on a scatterer isτz =∞ n =1n m =−n m (|a nm |2+|b nm |2−|p nm |2−|q nm |2)/P (11)in units of¯h per photon,whereP=∞n=1n m=−n|a nm|2+|b nm|2(12)is proportional to the incident power(omitting a unit conversion factor which will depend on whether SI,Gaussian,or other units are used).This torque includes contributions from both spin and orbital components,which can both be calculated by similar formulae(Crichton&Marston2000).Again,one can convert these values to SI units by multiplying by P/ω,whereωis the optical frequency.5.1.ImplementationOne routine,forcetorque.m,is provided for the calculation of the force,torque and spin transfer.The orbital angular momentum transfer is the difference between the torque and the spin transfer.The incoming and outgoing power(the difference being the absorbed power)can be readily calculated directly from the expansion coefficients, as can be seen from(12).6.Miscellaneous routinesA number of other routines that do not fall into the above categories are included.These include:(i)Examples of use.(ii)Routines for conversion of coordinates and vectors from Cartesian to spherical and spherical to Cartesian.(iii)Routines to automate common tasks,such asfinding the equilibrium position of a trapped particle,spring constants,and force maps.(iv)Functions required by other routines.7.Typical use of the toolboxTypically,for a given trap and particle,a T-matrix routine(usually tmatrix mie.m) will be run once.Next,the expansion coefficients for the beam are found.Depending on the interests of the user,a function automating some common task,such asfinding the equilibrium position within the trap,might be used,or the user might directly use the rotation and translation routines to enable calculation of the force or torque at desired positions within the trap.The speed of calculation depends on the size of the beam,the size of the particle, and the distance of the particle from the focal point of the beam.Even for a wide beam and a large distance,the force and torque at a particular position can typically be calculated in much less than one second.(a)(b)Figure1.Gaussian trap(example gaussian.m).Force on a sphere in a Gaussianbeam trap.The half-angle of convergence of the1/e2edge of the beam is50◦,corresponding to a numerical aperture of1.02.The particle has a relative refractiveindex equal to n=1.59in water,and has a radius of2.5λ,corresponding to a diameterof4.0µm if trapped at1064nm in water.(a)shows the axial trapping efficiency as afunction of axial displacement and(b)shows the transverse trapping efficiency as afunction of transverse displacement from the equilibrium point.(a)(b)guerre–Gauss trap(example lg.m).Force on a sphere in a Laguerre–Gauss beam trap.The half-angle of convergence of the1/e2outer edge of the beamis50◦,as infigure1.The sphere is identical to that infigure1.(a)shows the axialtrapping efficiency as a function of axial displacement and(b)shows the transversetrapping efficiency as a function of transverse displacement from the equilibrium point.Compared with the Gaussian beam trap,the radial force begins to drop offat smallerradial displacements,due the far side of the ring-shaped beam no longer interactingwith the particle.0.0250.020.0150.010.005Figure3.Trapping landscape(example landscape.m).The maximum axial restoringforce for displacement in the direction of beam propagation is shown,in terms of thetrapping efficiency as a function of relative refractive index and microsphere diameter.The trapping beam is at1064nm and is focussed by an NA=1.2objective.This type ofcalculation is quite slow,as the trapping force as a function of axial displacement mustbe found for a grid of combinations of relative refractive index and sphere diameter.At the left-hand side,we can see that the trapping force rapidly becomes very small asthe particle size becomes small—the gradient force is proportional to the volume of theparticle for small particles.In the upper portion,we can see that whether or not theparticle can be trapped strongly depends on the size—for particular sizes,reflection isminimised,and even high index particles can be trapped.More complex tasks are possible,such asfinding the optical force as a function of some property of the particle,which can,for example,be used to determine the refractive index of a microsphere(Kn¨o ner et al.2006).Figures1to4demonstrate some of the capabilities of the toolbox.Figure1shows a simple application—the determination of the force as a function of axial displacement from the equilibrium position in a Gaussian beam trap.Figure2shows a similar result, but for a particle trapped in a Laguerre–Gauss LG03beam.Figure3shows a more complex application,with repeated calculations(each similar to the one shown infigure 1(a))being used to determine the effect of the combination of relative refractive index and particle size on trapping.Finally,figure4shows the trapping of a non-sphericalFigure4.Optical trapping of a cube(example cube.m).A sequence showing theoptical trapping of a cube.The cube has faces of2λ/n medium across,and has arefractive index of n=1.59,and is trapped in water.Since the force and torquedepend on the orientation as well as position,a simple way tofind the equilibriumposition and orientation is to“release”the cube and calculate the change in positionand orientation for appropriate time steps.The cube can be assumed to always bemoving at terminal velocity and terminal angular velocity(Nieminen,Rubinsztein-Dunlop,Heckenberg&Bishop2001).The cube begins face-up,centred on the focalplane of the beam,and to one side.The cube is pulled into the trap and assumesa corner-up orientation.The symmetry optimisations allow the calculation of the T-matrix in20minutes;otherwise,30hours would be required.Once the T-matrix isfound,successive calculations of the force and torque require far less time,on the orderof a second or so.particle,a cube.Agreement with precision experimental measurements suggests that errors of less than1%are expected.8.Future developmentWe are actively engaged in work to extend the range of particles for which we can model trapping.This currently included birefringent particles and particles of arbitrary geometry.Routines to calculate the T-matrices for such particles will be included in the main when available.Other areas in which we aim to further improve the toolbox are robust handling of incorrect or suspect input,more automation of tasks,and GUI tools.We also expect feedback from the optical trapping and micromanipulation community to help us add useful routines and features.ReferencesAbraham M1909Rendiconti Circolo Matematico di Palermo28,1–28.Abraham M1910Rendiconti Circolo Matematico di Palermo30,33–46.Bayoudh S,Nieminen T A,Heckenberg N R&Rubinsztein-Dunlop H2003Journal of Modern Optics 50(10),1581–1590.Bishop A I,Nieminen T A,Heckenberg N R&Rubinsztein-Dunlop H2003Physical Review A 68,033802.Bishop A I,Nieminen T A,Heckenberg N R&Rubinsztein-Dunlop H2004Physical Review Letters 92(19),198104.Brock B C2001Using vector spherical harmonics to compute antenna mutual impedance from measured or computedfields Sandia report SAND2000-2217-Revised Sandia National Laboratories Albuquerque,New Mexico,USA.Chaumet P C,Rahmani A,Sentenac A&Bryant G W2005Physical Review E72,046708.Choi C H,Ivanic J,Gordon M S&Ruedenberg K1999Journal of Chemical Physics111,8825–8831. Collett W L,Ventrice C A&Mahajan S M2003Applied Physics Letters82(16),2730–2732. Crichton J H&Marston P L2000Electronic Journal of Differential Equations Conf.04,37–50. Doicu A&Wriedt T1997Applied Optics36,2971–2978.FarsundØ&Felderhof B U1996Physica A227,108–130.Gauthier R C2005Optics Express13(10),3707–3718.Gouesbet G&Grehan G1982Journal of Optics(Paris)13(2),97–103.Gumerov N A&Duraiswami R2003SIAM Journal on Scientific Computing25(4),1344–1381.Han Y,Gr´e han G&Gouesbet G2003Applied Optics42(33),6621–6629.Han Y&Wu Z2001Applied Optics40,2501–2509.Hoekstra A G,Frijlink M,Waters L B F M&Sloot P M A2001Journal of the Optical Society of America A18,1944–1953.Humblet J1943Physica10(7),585–603.Jackson J D1999Classical Electrodynamics3rd edn John Wiley New York.Jauch J M&Rohrlich F1976The Theory of Photons and Electrons2nd edn Springer New York. Kahnert M2005Journal of the Optical Society of America A22(6),1187–1199.Khrapko R I2001American Journal of Physics69(4),405.Kn¨o ner G,Parkin S,Nieminen T A,Heckenberg N R&Rubinsztein-Dunlop H2006Measurement of refractive index of single microparticles.Lock J A2004a Applied Optics43(12),2532–2544.Lock J A2004b Applied Optics43(12),2545–2554.Lorenz L1890Videnskabernes Selskabs Skrifter6,2–62.Maia Neto P A&Nussenzweig H M2000Europhysics Letters50,702–708.Mazolli A,Maia Neto P A&Nussenzveig H M2003Proc.R.Soc.Lond.A459,3021–3041.。

第28卷第3期2002年5月 光学技术OPTICAL TECHN IQU EVol.28No.3May　2002 文章编号:100221582(2002)0320231203一种基于虚拟基准的虚拟环规———检测螺纹的新方法Ξ洪迈生,苏恒,魏元雷,李自军,梁学军(上海交通大学机械工程学院,上海　200030)摘　要:提出一种基于计算机CCD视觉和虚拟基准的螺纹虚拟环规检测技术,给出在螺纹轴截面和正交投影间基准转换的关系式,根据该转换关系建立虚拟基准,指出了按“虚拟基准”构筑“虚拟量规”的新概念。

虚拟环规法检测效率高,成本低,非接触测量,易实现自动在线检测。

研制出了原理样机,实现了用虚拟螺纹环规对螺钉的逐个检测及与普通实体环规比对的100%吻合。

关键词:虚拟基准;虚拟环规;螺纹测量中图分类号:TM930.9;TP336 文献标识码:AVirtual ring:a ne w technique of scre w measurementHONG Mai2sheng,SU Heng,WEI Y uan2lei,LI Zi2jun,LI ANG Xue2jun(School of Mechanical Engineering,Shanghai Jiaotong University,Shanghai　200030,China) Abstract:A novel screw fastener virtual ring(VR)measurement technique based on CCD computer vision and virtual da2 tum(VD)is proposed.The transformation relationship from the screw axial section to its orthogonal projection is given.VD be built based on the relationship.The new VR is constructed according to the VD.Virtual ring test method has some characteris2 tics such as high efficiency,low cost,non2contact detection and easy to realize on2line automation measurement.The prototype is successfully developed and the metrological correspondence match between the tradition ring gauge and the VR technology is 100percent.K ey w ords:virtual ring;virtual datum;screw measurement1　引　言目前有些企业还在用外购的商品化普通螺纹环规(“实体环规”或“实体量规”)逐个检测螺钉,不仅费时费工、劳动强度大,而且仅一个尺寸规格的螺钉就需配上5套工作量规:通端工作环规、通端验收环规、止端工作环规、通端光滑卡规、止端光滑卡规;7套校对量规:校通2通、校通2止、校通2损、验通2通、校止2通、校止2止、校止2损,合共12套实体量规,造成备品和维护保养等一系列的问题。

Unit 1 --------mirage [mi'rɑ:ʒ] n. an optical illusion caused by hot air conditions, esp. that of a sheet of water seeming to appear in the desert or on a hot road;(fig.) any illusion or hope that can not be fulfilled.illusion [i'lu:ʒən] n. an idea or belief which is not true or not what it seems to be. con[kɒn] n. (sl.) instance of cheating sb.; confidence trickinfallible [in'fæləbl] adj.绝无错误的, 绝对可靠的; never failing; always effective; incapable of making mistakes or doing wrongsquarely ['skwɛəli] adv. 成方形地, 成直角地, 直接地, 坚定地; directlyprospect ['prɔspekt] n.希望,前景,景色v.勘探,寻找a possible or likely customer or client rip [rip] vt.撕裂,扯开n.裂口,裂缝,撕裂divide or make a hole in (sth.) by pulling sharply flabby ['flæbi] adj. 软弱的, 没气力的, 不稳的feeble and weak; ineffectiveseedy ['si:di] adj. 褴褛的, 破旧的, 不体面的shabby-looking; disreputablegreasy ['gri:zi] adj.油腻的, 滑溜溜的, 油滑的producing an excessive amount of oily secretionsstreetwalker n. (also street-girl) a prostitute who waits for business in the streetcall girl n. a prostitute who makes appointments by telephoneaforementioned [ə'fɔ:'menʃənd] adj. (also aforesaid) mentioned or referred to earlierdevious ['di:viəs] adj. 迂回的, 弯曲的, 不正直的cunning; dishonesthitchhiker ['hitʃhaikə] n. 搭便车的旅行者, 短篇广告, 顺便插入的广告a person who travels by obtaining free rides in other people’s carssnap [snæp] adj.突然的, 匆忙的done suddenly without allowing time for careful thoughts or preparationerroneous [i'rəuniəs] adj. 错误的, 不正确的incorrect; mistakendevastating ['devəsteitiŋ] adj.毁灭性的, 破坏性的, 惊人的, 压倒性的, 有魅力的causing severe shock; very destructive devastate v. 破坏granted adv. 假定，假设used to admit the truth of a statement beforeintroducing a contrary argumenteloquent ['eləkwənt] adj. 雄辩的, 有口才的, 动人的(of speech or writing) well expressed and effective in persuading peoplemagnetic [mæg'netik] adj.有磁性的, 有吸引力的having an unusual; powerful attraction romp [rɔmp] vi. 嬉闹玩笑, 欢快地迅速奔跑vi. 轻易地取得胜利win; succeed quickly or without apparent effort; play noisily and roughly with a lot of running and jumping unassuming ['ʌnə'sju:miŋ]adj. 谦逊的, 不装腔作势的(of a person) quiet and showing no desire for attention or admirationglib [glib] adj. 能说善道的, (说话)不假思索的, 轻易随口的speaking or spoken fluently and without hesitation, but not sincerely or trustworthilyflamboyant [flæm'bɔiənt] adj.艳丽的,炫耀的showy, very confident and extravagant turnover n. the rate at which people leave an organization and are replaced by others unwarranted ['ʌn'wɔrəntid] adj. 无根据的, 未经授权的, 无保证的lacking a good reason; unnecessary and unjustifiedattorney n. a lawyerroot canal n. 牙根管, 牙根管填充手术sedan [si'dæn] n. (美)厢式小轿车, 单舱汽艇, 轿子window-dressing n. presentation of facts, etc. in a way that creates a good(and often false) impressionrapport [ræ'pɔ:t] n.关系, 亲善, 一致sympathetic and harmonious relationshipstem from源于, 来自于arise from; have as its origin or causetake to start to likecount on ['kauntɔn] 依靠, 指望rely on with confidenceUnit 3 ---------giddiness ['gidinis] n. 眼花, 眩晕, 轻率the state of being rarely serious or living for the pleasure of the momentlarder ['lɑ:də] n. 食品贮藏室, 伙房, 食橱perversity [pə'və:siti] n. 刚愎, 堕落, 乖僻the quality or state of being unreasonable in one’s behaviorhilarious [hi'lɛəriəs] adj.欢闹的, 愉快的joyful; extremely amusingchuck [tʃʌk] n.抛掷,卡盘v.扔, 抛掷, 撵走(infml.) dismiss; throw out expostulation [iks'pɔstju'leiʃən] n.劝告; 谏言remonstrance; earnest and kindly reasoning against something one intends to do or has doneunscrupulous [ʌn'skru:pjuləs] adj. 肆无忌惮的, 不道德的not careful in details, esp. not caring about honesty and fairness in getting somethingamendment [ə'mendmənt] n.修正，改进a change made by correction; improvement qualm [kwɔ:m] n. 疑惧, 紧张不安feeling of doubt, esp. about whether what one is doing is right; misgiving(疑虑，怀疑)discreditable [dis'kreditəbl] adj. 丢了信用的, 不名誉的, 耻辱的（of behavior）causing a loss of reputation; shamefulconvict ['kɔnvikt,kən'vikt] vt.宣判..有罪, 使..知罪find (sb.) guilty of a crime, esp. in a court of lawvindictive [vin'diktiv] adj. 有报仇心的, 怀恨的, 惩罚的too unwilling to forgive; having or showing the desire to harm someone from whom has been receivedscoundrel ['skaundrəl] n. 无赖a wicked, esp. bold and selfish man; a villain philander [fi'lændə] vi. 调戏玩弄女人(of a man) amuse oneself by making love to women, with no serious intentionsgrudge [grʌdʒ] vt.不愿, 吝惜, 嫉妒give or allow (sth.) unwillinglylevy ['levi]vt.征收, 发动(on, upon) demand and collect (a payment) by authority or force; imposescapegrace ['skeipˌgreis] n. 不可救药的恶棍, 饭桶a complete rascalgutter ['gʌtə] n.排水沟, 槽, 贫民区(fig.) poor or debased state of lifeinfamous ['infəməs] adj. 无耻的, 臭名昭著的dissolute ['disəlu:t] adj. 放荡的, 风流的, 肆意挥霍的indifferent to moral restraints; given to immoral or improper conduct; dissipatedrogue [rəug] n.流氓, 调皮鬼, 离群野兽,[农]劣种a very dishonest person, esp. a man workhouse n. 劳教所, <英>贫民院yacht [jɔt] n.游艇, 快艇sovereign ['sɔvrin] n.元首, 君主, 最高统治者,(一)金镑Unit 5 ---------mount [maunt] v.登上,爬上, 装上, 上升organize and launch(an attack, campaign, etc.) en route on or along the wayultimatum [ˌʌlti'meitəm] n. 最后通牒final statement of conditions to be accepted or rejected without discussiontardiness ['tɑ:dinis] n. 缓慢, 迟延latenessclamp [klæmp] vt.夹住, 强加, 压制grip or hold (sth.) tightlyriot ['raiət] n.暴乱, 骚乱, 喧闹wild or violent disturbance by a crowd of people squabble ['skwɔbl] n. 争论, 口角a noisy quarrel about sth. Unimportantairborne ['ɛəbɔ:n] adj.空运的, 空中传播的, 起飞后在飞行中done or being in the air intone [in'təun] v.吟咏,吟诵speak or recite in a singing voice, or say sth. in a solemn voice enlist [in'list] vt.征募, 使入伍,获得...支持obtain (help, support, etc.)charity ['tʃæriti] n.慈善, 宽厚, 慈善机关(团体), 仁慈drive n. 运动;宣传活动an organized effort or campaign to achieve sth.de rigueure adj. (Fr.) strictly required, as by etiquette, usage, or fashiondraft [dræft]n.草稿, 草图, 汇票, 征兵vt.起草, 征兵, 选秀choose (people) and send them somewhere for a special tasktightrope ['taitrəup]n. 拉紧的绳索, 极其危险的处境 a rope stretched tightly high above the ground, on which acrobats perform featsenunciate [i'nʌnsieit] v. 发音, (清楚地)表达say or pronounce words clearlyone-liner n. a brief joke or witty remarktruculent ['trʌkjulənt] adj. 野蛮的, 粗野的, 残酷的aggressively hostile; belligerent buttress ['bʌtris] n. 扶墙, 拱壁vt. 支持give encouragement or support to caricature ['kærikətʃuə] n.讽刺画, 讽刺, 歪曲, 笨拙的模仿guise [gaiz] n. 装束, 外观, 伪装, 借口assumed appearance or mere semblancegag n. a joke, esp. one introduced into a script or an actor’s partsuffice vi. Be enough or adequate, as for needs or purposesblitz [blits] n. 闪击战a sudden intensive military attack, esp. from the airbolster ['bəulstə]vt.支持, 鼓励supportfoster ['fɔstə] vt.领养, 培养, 促进, 鼓励, 抱有（希望等）promote the growth or development ofcitadel ['sitədl] n. 城堡, 要塞aloofness [ə'lu:fnis] n.冷漠;远离indifference; the state of being reserved or reticent anecdote ['ænikdəut] n.轶事, 奇闻contagion [kən'teidʒən] n. 传染病, 接触传染, 蔓延the ready transmission or spread of an idea, emotion, etc.defiant [di'faiənt]adj. 挑衅的, 目中无人openly opposing or resisting sb. or sth. implore v. 恳求，哀求ladle ['leidl] n. 杓子, 长柄杓vt. 以杓舀取Unit 8 --------populate ['pɔpjuleit] v. 构成人口, 居住于live in (an area) and form its population deceptive [di'septiv] adj.骗人的, 虚伪的,诈欺的tending or having power to deceive; misleadingmasculine ['mæskjulin] adj.男性的, 有男子气概的, 阳性的of or having the qualities suitable for a manbracket ['brækit] n.支架, 托架, 括弧a group or category within specified limits falsify ['fɔ:lsifai] vt.伪造, 歪曲alter(e.g. a document) falsely; present(sth.) falsely enslave [in'sleiv] vt. 使做奴隶, 使处于奴役的状态make a slave of (sb.)cog [kɔg] n. 齿any of the teeth round the edge of a wheel that cause it to move or be moved by another wheeloversight ['əuvəsait] n. 疏忽, 失察, 监管, 看管unintentional failure to notice sth.spur [spə:] vt.刺激, 鞭策,促进strongly encourage(sb. or sth.) to do better, achieve more, etc.; incite or stimulateflirt [flə:t] vi.调情, 玩弄, 掠过,轻率对待behave (toward sb.) in a romantic or suggestive way but without serious intentionsdemotion [di'məuʃən] n.降级,降职,降等the act of reducing sb. to a lower rank or grade banter ['bæntə]n/ v. 戏弄, 开玩笑playful, good-humoured teasingscarlet ['skɑ:lit] n/adj.猩红, 绯红色, 红衣dissect [di'sekt] v. 解剖, 切细, 仔细研究, 详细分析cut up(a dead body, a plant, etc.) in order to study its structurebluff [blʌf] v/n. 虚张声势the act of trying to deceive sb. by pretending to be stronger, braver, cleverer, etc. than one isabysmally [ə'bizməli] adv. 深不可测地, 极坏地extremely; utterlybait [beit] n.饵, 引诱vt.以饵引诱, 放饵, 逗弄attract or temptmagnate ['mægneit] n. 巨头a wealthy and powerful landowner or industrialist orchestra ['ɔ:kistrə] n.管弦乐队zenith ['zi:niθ] n. 顶点, 天顶, 全盛(flg.) highest point (of power, prosperity, etc.);peak becoming adj. 合适的, 适宜的; 有吸引力的; 好看的prima ballerina ['pri:məˌbælə'rinə] (Latin)a leading woman dancer in a ballet mastermind n.才华横溢的人; 策划者; 智囊v.指导, 策划, 主持obliterate [ə'blitəreit] v. 涂去, 擦去, 删除remove all signs of (sth.); rub or blot outat stake在危机关头come by obtainexert oneself make an effortin the nick of time only just in time; at the last momentUnit 7 --------incandescent [ˌinkæn'desnt] adj. 光亮的, 发白热光的, 白热化的characterized by growing zeal. e.g. People living below the poverty line are incandescent with rage at the news of increased unemployment.tentative ['tentətiv] adj.不确定的, 暂时的, 试验性质的, 犹豫不决的done, said, etc. to test sth.; hesitant or explorative; not definite or decisive e.g. My friend and I have made tentative plans to take a trip to Seattle and some nearby cities in July this year. trepidation ['trepi'deiʃən] n. 恐惧, 惊惶, 忧虑great fear or worry about sth. unpleasant that may happen e.g.The threat of an epidemic outbreak caused great alarm and trepidation among the people of Algeria and Egypt.potency ['pəutənsi] n.效力, 潜能, 权力power; strengthe.g. With no outstanding achievements, he owed his popular support in the election to the potency of his propaganda machine. （[ˌprɔpəˈgændə] n. 宣传）impostor [im'pɔstə] n. 冒充者,骗子a person who deceives by pretending to be sb. Else e.g. Pablo Picasso once said that people who made their business were mostly impostors, and their pictures were infected with stupidity and poverty of soul.bail out v.保释, 跳伞, 往外舀水bail(保释金)引申：to escape from difficult situation e.g. In the recent crisis no banks could manage to bail out the companies feeling financial pressure.get away with not be punished for sth. e.g.“Nobody gets away with insulting like that!” Robert cursed in anger, contemplating plans of revenge.speculate on v. 思索；猜测；推测e.g. Scientists have been speculating on the origin of life for centuries, but no satisfactory answers have been offered yet.。

Delivered by Ingenta to:University of PatrasIP : 210.101.131.232Wed, 20 Jun 2012 09:30:48RESEARCH ARTICLECopyright ©2012American Scientific Publishers All rights reservedPrinted in the United States of AmericaJournal ofNanoscience and NanotechnologyV ol.12,2607–2611,2012Synthesis and Luminescence Properties of ZnO:Eu 3+Nano Crystalline via a Facile Solution MethodShihua Zhao 1 ∗,Fangjie Shu 1,Yanmin Li 1,Cuimei Liu 1,Wenwen Shan 2,Yuting Cui 1,and Lei Yang 31Department of Physics and Information Engineering,Shangqiu Normal University,Shangqiu,Henan Province 476000,P .R.China2North China University of Water Conservancy and Electric Power,Zhengzhou,Henan Province 450011,P .R.China3College of Materials Science and Engineering,Hunan University,Changsha,Hunan Province 410082,P .R.ChinaDifferent ZnO:Eu 3+nanocrystalline were obtained from a facile solution method with two different precipitators.The comparison of photoluminescence property of two different ZnO:Eu 3+nanocrys-talline was performed.The XRD patterns and the PL spectra indirectly indicate that the dopant Eu 3+ions had entered into the crystal lattices of ZnO.The study on the PL spectra of the as-prepared ZnO:Eu 3+nanocrystalline shows that with the change of dopant concentration,the ratio of rela-tive emission intensity of electric dipole transition to magnetic dipole transition changes,which fully expresses that the presence of the inversion centers is associated with the dopant concentration of Eu 3+.Keywords:Nanocrystalline,Electron Transition,Emission Band,Photoluminescence (PL).1.INTRODUCTIONIt is known that ZnO nanostructures have been studied extensively owing to their potential uses in nanodevices and optical materials.1–5Up to now,ZnO nanowires,6nanobelts,7nanorods,8nanoparticles,9nanoleaf 10and nanotubes,5etc.,have been synthesized.Rare earth (RE)ions incorporated into ZnO nanoparticles can result in remarkable changes in the optical properties of ZnO.Among the RE,Eu 3+ions are an interesting candidate due to its red lines at about 610nm.So,there have been many preparation methods for ZnO-based nanomaterials.11–14However,those approaches mentioned above have many disadvantages in cost,facilities and complexity.Especially,the experimental conditions are hard to be controlled.So many researchers hope to find a low-temperature and simple synthesis method.To our best knowledge,the per-formance of properties comparison with different precipi-tators is very little.In this work,a facile method was used for growing precursors of ZnO with two different precip-itators in solution at room temperature.Subsequently,the precursors could transform into ZnO under the annealing∗Author to whom correspondence should be addressed.process.This approach has advantages in cost,facili-ties,complexity and energy consumption.Especially,this approach can be put into mass production in the future.2.EXPERIMENTAL DETAILSIn the experiment,1mol of Zn(NO 3 2·6H 2O (AR)is dis-solved in deionized water to form aqueous solution.0.01,0.05,and 0.1mol/L are three different molar concentration of Eu(NO 3 3solution,which were obtained from dissolv-ing Eu 2O 3powders (AR)in nitric acid via evaporation process and then adding to the above-mentioned aqueous solution to form 1L of neutral mixed solution,respec-tively.That is,the molar ratios of Eu 3+to Zn 2+in the homogeneous mixed solution are 1:100,5:100and 10:100,respectively.Three solutions with different molar ratio of Eu 3+to Zn 2+are obtained.Each solution is divided into two parts and labeled 1,2,3,1#,2#and 3#,respectively,on account of using different precipitator.The solutions 1,2and 3express that urea is the precipitator and the molar ratio of Eu 3+to Zn 2+in the solutions are 1%,5%and 10%,respectively.Similar to the labels,the solutions 1#,2#and 3#show that ammonia is the precipitator and the molar ratio of Eu 3+to Zn 2+in the solutions are 1%,5%Delivered by Ingenta to:University of Patras IP : 210.101.131.232Wed, 20 Jun 2012 09:30:48R E S E A R C H A R T I C L Eand 10%,respectively.The beakers filled with the 1,2and 3solutions are sealed with the adhesive tape after some urea is added into three solutions.The solutions of the 1#,2#and 3#are agitated on the magnetic force beater while the precipitator of ammonia is added into every beaker.And then,the beakers 1,2and 3are put into an oven kept at 80 C for 24h.After reaction for 24h,the precur-sors of the samples 1,2and 3were taken out and washed repeatedly using deionized water.Subsequently,a series of samples with different dopant concentration and precipita-tor were put into a tube furnace and kept at 800 C for 2h.Finally,the samples of 1,2,3,1#,2#and 3#are obtained.The as-prepared samples were detected by X-ray diffraction (XRD)measurements on a SIEMENS D-5000X diffractometer.The morphology of the as-synthesized sam-ple was obtained with scanning electron microscopy (SEM JSM-6700F).The photoluminescence was taken on a Hitachi F-2500FL spectrophotometer with a Xe lamp as the excitation light source.3.RESULTS AND DISCUSSION Figure 1shows the XRD patterns of the as-prepared sam-ples with different dopant concentrations and precipitatorsannealed at 800 C for 2h.From the XRD patternsshownFig.1.XRD patterns of the as-prepared samples with different dopant concentration and precipitators.in Figure 1,it can be seen clearly that the six samples have the same diffraction crystal planes,which can be indexed to hexagonal ZnO according to the values in the standard card (JCPDS 36-1451).According to the Scherrer formula,the diffraction peaks in Figure 1(A)are sharper than that of Figure 1(B),so the sizes of samples labeled #are larger than samples with no label.In addition to those mentioned above,it must be pointed out that compared with JCPDS date (not shown here),all the diffraction peaks are shifted slightly towards the low diffraction angle,which indicates that the lattice parameters of Eu-doped ZnO are a little larger than those of undoped ZnO.There is no peak related to Eu,so it is suggested that Eu 3+ions may occupy Zn sites or interstitial sites in the ZnO crystal lattice.The typical SEM images of the as-prepared ZnO:Eu 3+are depicted in Figure 2.Figures 2(A)and (B)are the SEM images of the ZnO:Eu 3+prepared by the precipi-tator of urea.Figures 2(C)–(E)are the SEM images of the ZnO:Eu 3+resulted from the precipitator of ammonia.From Figures 2(A)and (B),it can be seen that large scale particles came up and the average sizes of those parti-cles are about 100nm.Figures 3(C)and (D)show that morphologies of the samples of ZnO:Eu 3+are in column and the diameter and length are about 2 m and 6 m,respectively.To further demonstrate morphologies of the samples,a high-magnification SEM of the column indi-cated by the arrow in Figure 2(D)is performed,which is shown in Figure 2(E).From Figure 2(E),it can be seen clearly that columns are composed of many flakes and the thickness of the flakes are about 10nm.That is to say,about 600parallel layers lap over each other to form the morphology of column.In other words,ammonia as the precipitator tends to group behavior.The reason of group behavior is possibly that OH −ions resulted from ammonia react with Zn 2+and Eu 3+quickly to form hydroxide precipitates,which result in the higher local concentration of precipitates rather than homogeneous concentration in the ly,OH −ions of ammonia combines with Zn 2+and Eu 3+ions at once rather than homogeneous dispersal,which makes for the local group behavior.However,OH −ions arisen from hydrolyzation of urea are diffused in the mixed solution,which bring about the homogeneous reaction with the Zn 2+and Eu 3+ions.In a word,the latter reactions are based on the homogeneous mixture of Zn 2+,Eu 3+and OH −ions,which make the hydroxide precipitates come into being uniformly in whole solution rather than the local reaction.The growth of the ZnO:Eu 3+samples may be divided into two separate steps,the reaction of Zn 2+and Eu 3+with OH −ions,and the subsequent formation of ZnO:Eu 3+samples.Those processes involve the following reactions:NH 3·H 2O →NH +4+OH −CO NH 2 2+3H 2O →CO 2+2NH 3·H 2ODelivered by Ingenta to:University of Patras IP : 210.101.131.232Wed, 20 Jun 2012 09:30:48RESEARCH ARTICLEFig.2.Typical SEM images:(A)and (B)show the SEM images of the samples with urea as the precipitator,(C)and (D)show the SEM images of the samples with ammonia as the precipitator,(E)is a high-magnification SEM image of the “column”indicated by the arrow in Figure D.Zn 2++2OH −→Zn OH 2Eu 3++3OH −→Eu OH 3Zn OH 2→ZnO +H 2O 2Eu OH 3→Eu 2O 3+3H 2OTo further demonstrate the dependence of different pre-cipitators and dopant concentration on the photolumines-cence properties,the PL spectra of the ZnO:Eu 3+samples are performed,which are shown in Figures 3and 4.The PL excitation spectra monitored by 611nm is shown in Figure 3.Figures 3(A)and (B)express excitation spectra of different samples with different dopant concen-tration and precipitators.From Figure 3,it can be seen clearly that 392nm is the most effective to the emission band of 611nm.According to the reports of Ref.15,there is a main peak at about 395nm in the excitation spectra of pure ZnO or Eu 2O 3,so using 392nm as the excitation wavelength can possibly excite ZnO and Eu 3+ions,simul-taneously.In addition to those mentioned above,it must be pointed out that the two shoulder peaks of 405nm and 408nm are possibly resulted from the energy level split of 395nm.Figure 4shows PL emission spectra of the samples with different dopant concentration and precipitators,mea-sured with an excitation of the 392nm lines of a Xe lamp.From Figure 4,it can be seen that the as-prepared ZnO:Eu 3+crystal can emit salmon pink lines (592nm)(A)(B)Fig.3.Excitation spectra of the as-prepared samples with different dopant concentration and precipitators.Delivered by Ingenta to:University of Patras IP : 210.101.131.232Wed, 20 Jun 2012 09:30:48R E S E A R C H A R T I C L E(A)(B)Fig.4.Emission spectra of the as-prepared samples with different dopant concentration and precipitators.and red lines (611nm).It is well-known that the peaks at595and 612nm derive mainly from the allowed magneticdipole transition (MDT 5D 0→7F 1 and electric dipole transition (EDT 5D 0→7F 2 of Eu 3+ions,respectively.According to the reported paper 16,the peaks near 595nm derived mainly from the allowed MDT,which required the inversion centers.However,the EDT did not require the inversion centers.So,from the comparison of the PL inten-sity of the MDT and EDT,it can be presumedly conjec-tured that whether the dominant Eu 3+ions have located the inversion centers or not.It should be pointed out that with the increase of dopant concentration,the number of inver-sion centers will change,which can be demonstrated by the Figure 4.It can also been seen that with the change of dopant concentration,the ratio of relative emission inten-sity of EDT to MDT change,which fully expresses that the presence of the inversion centers is associated with the dopant concentration of Eu 3+.In addition to those men-tioned above,it should be emphasized that there is no 510nm peak in Figure 4,which shows the possibility of energy transfer between ZnO and Eu 3+.If the pho-ton energies are absorbed by the defects on the surface states of ZnO,there will be a weak visible emission around 510nm.17Fig.5.A schematic drawing for possible mechanisms of electron tran-sitions in the excitation and emission processes.Based on the work,a schematic drawing for possi-ble mechanisms of electron transitions in the excitation and emission processes is proposed,which is shown inFigure 5.When the 392nm lines (3.17eV)excite the as-prepared samples,the electrons of Eu 3+absorb the pho-tons to transfer from the 7F 0energy level to 5L 6and 5D 2energy level,so there are two absorption peaks at 392nmand 466nm in Figure 3.After electrons are jumped to the higher energy lever,the deexcitation of the electrons would transfer back to the lower energy lever,which results in the luminescence due to the 5D 0→7F 1 2transitions.In the ZnO system,the electrons excitated to the higher energylevel would possibly return to the 5D 0level of Eu 3+ions,rather than to the ground state,which could be demon-strated by the absence of the 510nm visible emission bandin Figure 4,which is also the evidence to express that there is possibly an energy transfer between ZnO and Eu 3+.4.CONCLUSIONSIn summary,the ZnO:Eu 3+nanocrystallines have been prepared by a facile solution method.This approach has advantages in cost,facilities,complexity and energy con-sumption.From the XRD patterns,it is suggested thatEu 3+ions may occupy Zn sites or interstitial in the ZnO crystal pared with the SEM images of two different samples,it can be concluded that ammonia as theprecipitator tends to group behavior.The study on the PL spectra of those ZnO:Eu 3+crystallines at room tempera-ture shows that there is the possibility of energy transfer between ZnO and Eu 3+.A schematic drawing for possible mechanisms of electron transitions in the excitation andemission processes is also proposed.Acknowledgments:This work was supported by theYouth Scientific Research Foundation of Shangqiu NormalUniversity,China (Grant No.2011QN14),the Founda-tion and High-Tech Project of Henan Province (GrantNo.112300410258),the Henan Provincial Science andDelivered by Ingenta to:University of PatrasIP : 210.101.131.232Wed, 20 Jun 2012 09:30:48RESEARCH ARTICLETechnology Research Projects (Grant No.092102210343),the Henan Provincial Science and Technology research projects (Grant No.112300410269),the Natural Science Foundation of Henan Province (Grant No.2009A140009),the National Natural Science Foundation of China (Grant No.11104066),the National Natural Science Foundation of China (Grant No.11074160).References and Notes1.Z.J.Wang,P.L.Zhou,J.Liu,F.J.Wang,Y .J.Peng,and 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