新型稀土铕,铽β-二酮配合物的合成与荧光性质

采用克莱森缩合反应合成了一种新型的β-二酮化合物1-(4-氨基苯)-4,4,4-三氟丁烷-1,3-二酮(p-NBFA)。以其为第一配体,邻菲咯啉(phen)为第二配体,合成出新型Eu(Ⅲ),Tb(Ⅲ)三元配合物。通过元素分析确定了配合物的组成为Eu(p-NBFA)3phen和Tb(p-NBFA)3phen。红外光谱的分析表明p-NBFA中的氧原子以及phen中的氮原子与稀土离子进行了配位。紫外光谱表明第一配体p-NBFA为能量传递的主体,第二配体phen起协同作用。通过荧光光谱研究了配合物的发光性质,结果显示在Tb(p-NBFA)3phen中,除Tb3+的特征发射外,还可以观察到470nm的发射,进一步的研究表明,此处发射为配体p-NBFA的发射,这是由于配体的能级与Tb3+的发射能级较近,产生了逆传能过程。而在Eu(p-NBFA)3phen的发射谱中,均表现出稀土离子的特征发射,且发光强度较大,说明配体的能级与Eu3+的发射能级比较匹配。     

La~(3+)掺杂Eu~(3+)偏苯三酸邻菲咯啉三元配合物的合成和荧光性能

以偏苯三酸(TLA)为第一配体,邻菲咯啉(phen)为第二配体,合成了铕偏苯三酸邻菲咯啉及铕镧系列发光配合物Eu1-xLax(TLA)phen(x=0.0,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8)。通过红外光谱、TG-DTG和扫描电子显微镜对配合物进行了表征;通过荧光光谱分析,探讨了掺杂荧光惰性离子对三元配合物的发光性能的影响。结果表明:该系列配合物均表现为强的Eu3+的特征荧光,La3+的掺入能增强配合物的的荧光强度,但发射峰的位置基本上没有变化,其中5D0→7F1和5D0→7F2的跃迁发射较强,所有掺杂配合物的荧光强度都大于未掺杂的配合物的荧光强度。     

紫光化合物［Cd(bpdc)(phen)2(H2O)］·6H2O的合成、结构及荧光光谱研究

以2,4′-联苯二甲酸(H2bpdc)和1,10-邻菲罗啉(phen)为配体, 采用水热法合成一例三维超分子网状镉(Ⅱ)配合物［Cd(bpdc)(phen)2(H2O)］·6H2O (1)。通过单晶X射线衍射分析, 元素分析和红外光谱分析表征化合物1的结构。单晶X射线衍射分析结果表明, 化合物1属于三斜晶系, P1空间群, 中心金属Cd(Ⅱ)离子呈现六配位扭曲八面体构型, 通过两种氢键作用和π—π堆积作用形成三维超分子结构。同时, 对化合物1进行固态/溶液以及不同温度下的荧光性能测试。以350 nm为激发波长进行激发, 298 K固态时, 化合物1在390 nm处有强发射峰, 呈现紫色荧光;77 K固态时, 化合物1的荧光光谱具有两个发射谱带, 分别位于380和520 nm处, 是因为在低温时化合物1表现出精细结构。298 K时, 化合物1在DMSO溶液和CH3OH溶液中分别在380和375 nm有最大发射, 相对于固态最大发射波长发生蓝移, 呈现紫色荧光。这均是基于中心金属微扰配体中心的π*→π跃迁发射。研究了化合物1固态和溶液的荧光寿命, 化合物1荧光衰减过程包含双组分。298 K条件下, 化合物1在DMSO溶液中的寿命(τ1=1.73 μs和τ2=14.07 μs)比CH3OH溶液中的荧光寿命(τ1=1.21 μs和τ2=12.44 μs)长。此外, 77 K固态时的荧光寿命(τ1=1.96 μs和τ2=16.11 μs)长于298 K的固态荧光寿命(τ1=1.20 μs和τ2=11.34 μs), 这是因为低温条件下降低分子内部的非辐射跃迁, 从而延长固态荧光寿命。     

紫光化合物[Cd(bpdc)(phen)_2(H_2O)]·6H_2O的合成、结构及荧光光谱研究

以2,4′-联苯二甲酸(H2bpdc)和1,10-邻菲罗啉(phen)为配体,采用水热法合成一例三维超分子网状镉(Ⅱ)配合物[Cd(bpdc)(phen)2(H2O)]·6H2O(1)。通过单晶X射线衍射分析,元素分析和红外光谱分析表征化合物1的结构。单晶X射线衍射分析结果表明,化合物1属于三斜晶系,P1空间群,中心金属Cd(Ⅱ)离子呈现六配位扭曲八面体构型,通过两种氢键作用和π—π堆积作用形成三维超分子结构。同时,对化合物1进行固态/溶液以及不同温度下的荧光性能测试。以350nm为激发波长进行激发,298K固态时,化合物1在390nm处有强发射峰,呈现紫色荧光;77K固态时,化合物1的荧光光谱具有两个发射谱带,分别位于380和520nm处,是因为在低温时化合物1表现出精细结构。298K时,化合物1在DMSO溶液和CH3OH溶液中分别在380和375nm有最大发射,相对于固态最大发射波长发生蓝移,呈现紫色荧光。这均是基于中心金属微扰配体中心的π*→π跃迁发射。研究了化合物1固态和溶液的荧光寿命,化合物1荧光衰减过程包含双组分。298K条件下,化合物1在DMSO溶液中的寿命(τ1=1.73μs和τ2=14.07μs)比CH3OH溶液中的荧光寿命(τ1=1.21μs和τ2=12.44μs)长。此外,77K固态时的荧光寿命(τ1=1.96μs和τ2=16.11μs)长于298K的固态荧光寿命(τ1=1.20μs和τ2=11.34μs),这是因为低温条件下降低分子内部的非辐射跃迁,从而延长固态荧光寿命。     

惰性离子(La3+,Y3+,Gd3+)对配合物苯乙酮酸邻菲咯啉铕荧光性能的影响

以苯乙酮酸和邻菲咯啉为配体,不同摩尔比铕和惰性离子(La3 ,Y3 ,Gd3 )为中心离子,合成了系列配合物EuxRE1-xL3phen(RE=La,Y,Gd),测定了其荧光激发光谱和荧光发射光谱,研究了惰性离子(La3 ,Y3 ,Gd3 )对Eu3 荧光性能的影响.结果表明,配合物激发光谱相似,均在350～360 nm范围内出现最大激发,属于配体的吸收峰,在398 nm附近出现弱的激发为Eu3 的吸收峰;系列配合物荧光发射光谱相似,均显示Eu3 离子的特征发射光谱,位于583,595,617,654,703 nm附近出现5组强度不同的发射峰,分别归属为Eu3 的5D0-7F0,5D0-7F1,5D0-7F2,5D0-7F3,5D0-7F4能级跃迁.发射光谱表明,系列配合物中La3 离子对Eu3 的荧光发射峰峰位影响最大,EuxLa1-xL3phen中La3 的摩尔分数为0.7时,Eu3 的5D0-7F2跃迁可改变5.2 nm,而Y3 和Gd3 对Eu3 的荧光发射峰峰位影响较弱,配合物EuxY1-xL3phen和EuxGd1-xL3phen中Eu3 的荧光发射峰位变化较小,最大时仅改变2 nm;发射光谱强度表明,La3 对Eu3 的荧光发射影响最大,EuxLa1-xL3phen中La3 含量为0.7时,可使其相对荧光强度增大2倍以上,对其具有很好的敏化作用.这对人们寻找发光性能好、价格便宜的发光材料提供了理论依据.     

含氮配体构筑的单核锌Zn(Ⅱ)/双核Cu(Ⅰ)配合物蓝光材料的结构和荧光性能研究

采用溶剂热法合成出单核Zn(Ⅱ)配合物[Zn(2,6-PDA)(phen)H₂O]·H₂O (1)和双核Cu(Ⅰ)配合物{[Cu(μ-Ⅰ)(phen)H₂O]·H₂O}₂ (2) (2,6-H₂PDA=2,6吡啶二甲酸,phen=1,10-邻菲罗啉),通过单晶结构测试、元素分析和红外吸收光谱对结构进行表征,并研究了两种配合物在二甲基亚砜(DMSO)中及固态时的荧光光谱及DMSO溶液中紫外可见吸收光谱。配合物1和2的最大吸收峰分别出现在253和242 nm附近,相比于配体吸收峰均发生红移,在1和2中,主要呈现出中心金属离子微扰的phen的π→π*的跃迁,且吸收强度强于phen,说明中心金属离子与phen配位后,增加了有机配体在紫外区的吸收,利于配体对能量的吸收。1在DMSO溶液中的荧光发射峰位于361,379和392 nm,在固态时的荧光发射峰为407,434和467 nm,2在DMSO溶液中的荧光发射峰出现在422,443和461 nm,固态时荧光发射峰在442,469,501 nm,均呈现蓝光发射。配合物1和2的固态荧光发射光谱与相应的DMSO溶液中的发射峰相比分别红移55和23 nm,这是由于在固态时配合物1和2的分子中的π—π堆积相互作用和分子间的相互作用,特别是配合物2中存在强烈的Cu(Ⅰ)…Cu(Ⅰ)相互作用,降低了体系前线轨道之间的能量差。     

2,2′-联苯醚二甲酸和邻菲啰啉构筑的单核铽(Ⅲ)配合物:荧光性质及对Fe~(3+)的发光传感

采用水热法合成了一种新的配合物[Tb(2,2′-oba)_2(phen)_2]~-(H_3~+O)(2,2′-oba=2,2′-联苯醚二甲酸,phen=1,10-邻菲啰啉),并用X-ray单晶衍射仪测定了晶体结构。配合物是由两个邻菲啰啉和两个2,2′-联苯醚二甲酸铽离子构成的单核分子。配合物的荧光光谱在489,546,584和622nm处出现发射峰,归属为中心Tb~(3+5)D_4→7 FJ(J=6-3)跃迁产生的特征荧光。在546nm处的发射最强,对应于~5D_4→~7F_5跃迁,为绿光。探讨了不同金属阳离子对配合物的荧光效应影响。实验结果表明Fe3+对配合物具有显著的荧光猝灭作用,在生理环境pH 4.0~8.0范围内仍然适用,因此配合物可用于生命体系中的Fe~(3+)作荧光探针。     

稀土铕-芳香羧酸-邻菲罗啉三元有机配合物的合成、表征及发光性能

分别以4种芳香羧酸—对甲基苯甲酸(PMBA)、对氯苯甲酸(PCBA)、对溴苯甲酸(PBr BA)、对氨基苯甲酸(PABA)—作为第一配体,邻菲罗啉(phen)为第二配体,采用溶剂热法合成了4种稀土铕离子(Eu3+)的三元有机配合物。通过元素分析、红外光谱、热重分析等手段确定配合物的化学结构,结果表明,4种配合物的组成可表示为Eu L3phen·H2O(L=PMBA、PCBA、PBr BA、PABA),芳香羧酸配体和邻菲罗啉均与稀土Eu3+配位;铕配合物在318℃以上才开始出现明显失重,表明其具有良好的热稳定性。研究了4种芳香羧酸配体对紫外光的吸收性能。通过荧光光谱研究了配合物的发光性能,4种配合物均发出Eu3+的特征荧光,5D0→7F2电偶极跃迁发射峰强度顺序为:Eu(PBr BA)3phen·H2OEu(PMBA)3phen·H2OEu(PCBA)3phen·H2OEu(PABA)3phen·H2O;其国际照明委员会(CIE)色坐标均落在红光区域,能发出纯正的红光。     

新型三元配合物Tb(DPAB)_3IP的制备与发光性能

合成了邻菲罗啉的衍生物咪唑并[5,6-f]邻菲罗啉(IP),并以其为第二配体,二苯胺羰基邻苯甲酸(HDPAB)为第一配体,制备出新型稀土铽三元有机配合物Tb(DPAB)3IP。采用元素分析、红外光谱和紫外光谱对合成的配体及配合物进行了表征。通过荧光光谱研究了配合物的荧光性质,结果表明第二配体IP有较大的共轭体系,在紫外光激发下,配合物中的配体可将吸收的能量传递给稀土Tb3+离子,表现出较强的Tb3+离子的特征发射,且配体Tb(DPAB)3IP的荧光强度明显大于Tb(DPAB)3phen的荧光强度。这说明适宜的第二配体对配合物有很好的敏化发光作用,合成的Tb(DPAB)3IP是一种良好的绿光材料。     

基于多酸与1 ,4 ,5 ,8-萘二酰亚胺衍生物的稀土有机-无机杂化材料的设计与合成

基于有机-无机杂化材料的理念,利用稀土硝酸铽[Tb（NO₃）₃]、有机配体BINDI (BINDI=N,N′-双（5-间苯二甲酸）-1,4,5,8-萘二酰亚胺)及Keggin型多酸H₄SiW₁₂O₄₀·26H₂O在溶剂热的条件下反应,成功合成出多酸基稀土配位聚合物Tb₄[SiW₁₂O₄₀]·[BINDI)]₂·[DMA]₁₆。采用X-射线单晶衍射仪、X-射线粉末衍射仪、红外光谱仪、热重分析仪、紫外-可见吸收光谱仪、元素分析仪、荧光光谱仪和电子顺磁共振仪对稀土聚合物的结构组成、热稳定性、发光性能以及光致变色性能进行了表征。X-射线单晶衍射分析发现该稀土配位聚合物结晶于Tetragonal晶系,空间群为P4₂/n,展现出3D手性双螺旋网络结构特征,其中多酸阴离子SiW₁₂O₄₀(简写为{SiW₁₂})镶嵌在稀土有机基团形成的孔道中;红外及紫外吸收光谱分析发现稀土Tb3+与配体（BINDI）配位成键;荧光光谱表明,在380 nm的激发波长下,配体显示出最强荧光发射峰,位于441 nm处,而化合物的最强发射峰位于471 nm处。由于三价铽离子不易被氧化也很难被还原,所以化合物的荧光发射不能归因于金属与配体之间的电子辐射跃迁,且化合物的发射峰与配体的发射峰比较相近,因此荧光主要是配体BINDI的发光。另外Tb(Ⅲ)离子的特殊跃迁发射带没有出现是因为在荧光测试时由于光照的原因导致样品的颜色发生了突变,即发生了光致变色的现象,导致光诱导电子转移以致荧光猝灭。引起金属配合物荧光猝灭的原因通常是光致电子转移,而电子转移的方向是配体中的电子向金属空轨道转移（LMCT）所致,形成配合物后其最大发射峰红移或蓝移是由电子转移导致分子内电子分布的改变,从而引起HOMO-LUMO能隙的减小或增大所致,与配体荧光光谱相比,化合物的发射峰发生了红移。此外,电子顺磁共振结果表明由于化合物中的BINDI配体在紫外与可见光照射下发生电子转移形成配体自由基,以及多酸在光激发下,发生W5+→W6+的过程进一步促进该化合物发生光致变色现象。因此,该化合物具有极其敏锐光致变色的性质。     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.