Syntheses and spectroscopic properties of energy transfer systems based on squaraines

The purpose of this project was to prepare fluorescent dyes that could absorb energy at relatively short wavelengths, and fluoresce in the near-IR region. To achieve this, copper- and palladium-mediated C-N couplings were used to prepare the ‘cassettes’, i.e the carbazole derivative 3b and the carbazole-, phenothiazine-, and phenoazine-squaraines 4b-d. These compounds have carbazole, phenothiazine, and phenoazine donor-components that absorb around about 300-320 nm, and squaraine acceptor-parts that fluoresce in the range 650-700 nm. The efficiencies of energy transfer from the donor to the acceptor, and the overall quantum yields of the cassettes were determined.     

微乳液法合成白光LED NaLu(MO4)2:Eu3+/Eu3+,Tb3+(M=W, Mo)荧光粉

采用微乳液法制备NaLu(WO₄)_2-x(MoO₄)x:8%Eu³⁺(x=0, 0.5, 1.0, 1.5, 2.0)/y%Eu³⁺,5%Tb³⁺(y=1, 3, 5, 7, 9)系列荧光粉.通过X射线衍射(XRD)表征,所制样品的X射线衍射峰与标准卡片PDF#27-0729基本吻合,表明所制的样品为白钨矿结构,属于四方晶系.扫描电镜SEM显示制备的纳米粒子是梭子状的,粒径大约是110 nm.激发发射光谱显示,在Eu³⁺离子掺杂浓度为8%时,NaLu(WO₄)(MoO₄):Eu³⁺发光强度最大.NaLu(WO₄)_2-x(MoO)x :8%Eu³⁺(x=0, 0.5, 1.0, 1.5, 2.0)荧光粉在Mo/W比达到1:1(x=1)时发光强度最大,强烈的红光发射表明该材料可用于白光LED材料.该荧光粉在268、394和466 nm波长光激发下分别发出橙红色、黄色和淡黄色光,可以满足不同光色需要.NaLu(WO)(MoO):y%Eu³⁺,5%Tb³⁺(y=1, 3, 5, 7, 9)荧光粉,随着y值增大,从绿光区(x=0.278, y=0.514)进入白光区(x=0.356, y=0.373), (x=0.278, y=0.313),同时观察到Tb³⁺到Eu³⁺有效能量传递.     

Natural and artificial light-harvesting systems utilizing the functions of carotenoids

Carotenoids are essential pigments in natural photosynthesis. They absorb in the blue–green region of the solar spectrum and transfer the absorbed energy to (bacterio-)chlorophylls, and so expand the wavelength range of light that is able to drive photosynthesis. This process is an example of singlet–singlet energy transfer and so carotenoids serve to enhance the overall efficiency of photosynthetic light reactions. Carotenoids also act to protect photosynthetic organisms from the harmful effects of excess exposure to light. In this case, triplet–triplet energy transfer from (bacterio-)chlorophyll to carotenoid plays a key role in this photoprotective reaction. In the light-harvesting pigment–protein complexes from purple photosynthetic bacteria and chlorophytes, carotenoids have an additional role, namely the structural stabilization of those complexes. In this article we review what is currently known about how carotenoids discharge these functions. The molecular architecture of photosynthetic systems will be outlined to provide a basis from which to describe the photochemistry of carotenoids, which underlies most of their important functions in photosynthesis. Then, the possibility to utilize the functions of carotenoids in artificial photosynthetic light-harvesting systems will be discussed. Some examples of the model systems are introduced.     

微乳液法合成白光LED NaLu(MO_4)_2:Eu~(3+)/Eu~(3+),Tb~(3+)(M=W,Mo)荧光粉

采用微乳液法制备Na Lu(WO4)2-x(Mo O4)x∶8%Eu3+(x=0,0.5,1.0,1.5,2.0)/y%Eu3+,5%Tb3+(y=1,3,5,7,9)系列荧光粉。通过X射线衍射(XRD)表征,所制样品的X射线衍射峰与标准卡片PDF#27-0729基本吻合,表明所制的样品为白钨矿结构,属于四方晶系。扫描电镜(SEM)显示制备的纳米粒子是梭子状的,粒径大约是110 nm。激发发射光谱显示,在Eu3+离子掺杂物质的量分数为8%时,Na Lu(WO4)(Mo O4)∶Eu3+发光强度最大。Na Lu(WO4)2-x(Mo O4)x∶8%Eu3+(x=0,0.5,1.0,1.5,2.0)荧光粉在nMo/nW比达到1∶1(x=1)时发光强度最大,强烈的红光发射表明该材料可用于白光LED材料。该荧光粉在268、394和466 nm波长光激发下分别发出橙红色、黄色和淡黄色光,可以满足不同光色需要。Na Lu(WO4)(Mo O4)∶y%Eu3+,5%Tb3+(y=1,3,5,7,9)荧光粉,随着y值增大,从绿光区(x=0.278,y=0.514)进入白光区(x=0.356,y=0.373),(x=0.278,y=0.313),同时观察到Tb3+到Eu3+有效能量传递。     

分子荧光信号器件和光控分子开关研究的现状和进展

本文扼要介绍了分子荧光信号器件的现状和进展,并对其中一些基本问题进行了讨论。这是一个崭新的科学领域,涉及广泛的学科范围,值得引起重视.     

GdVO4:Ln3+(Ln=Eu,Tm,Dy)荧光粉的水热法制备及其发光性能

以EDTA为矿化剂,采用水热法制备了Gd VO4∶Dy~(3+)、Gd VO4∶Dy~(3+),Eu~(3+)和Gd VO4∶Dy~(3+),Eu~(3+),Tm~(3+)荧光粉,研究了所制备样品的相结构、形貌、荧光性质、Dy~(3+)到Eu~(3+)的能量传递及Dy~(3+)的4F9/2→6H15/2跃迁的衰减曲线。X射线衍射(XRD)确定了所合成的Gd VO4∶0.03Dy~(3+)、Gd VO4∶0.03Dy~(3+),0.07Eu~(3+)和Gd VO4∶0.03Dy~(3+),0.07Eu~(3+),0.07Tm~(3+)样品均为四方晶系;扫描电镜(SEM)显示Gd VO4∶0.03Dy~(3+),0.07Eu~(3+)和Gd VO4∶0.03Dy~(3+),0.07Eu~(3+),0.07Tm~(3+)均为棒状结构,平均长度分别约为0.458和0.491μm;通过研究Gd VO4∶Dy~(3+),Eu~(3+)的发射光谱和衰减曲线,佐证了Dy~(3+)到Eu~(3+)的能量传递过程,并确定了其能量传递的机制为偶极-偶极相互作用。通过调节Gd VO4∶0.03Dy~(3+),x Eu~(3+)荧光粉中Eu~(3+)的掺杂浓度实现了准白光输出(0.424,0.350);调节Gd VO4∶0.03Dy~(3+),0.07Eu~(3+),y Tm~(3+)荧光粉中Tm~(3+)的掺杂浓度,也实现了白光输出(0.346,0.301)。     

Cr4+：YAG被动调Q激光器中受激粒子上转换效应对脉冲的影响研究

分析和报道了受激粒子能量上转换(ETU)效应对Cr:YAG 被动调Q Nd:YAG/Nd:YVO₄激光器的输出脉冲影响研究.结合ETU理论分析和被动调Q速率方程组，得到了初始反转粒子密度，末态反转粒子密度和光强最大时反转粒子密度的比值变化对激光输出脉冲宽度和脉冲能量的影响，和实验结果相一致.同时讨论了降低ETU效应的方法，有助于这类被动调Q激光器的优化设计. 关键词： 受激粒子能量上转换 Cr:YAG饱和吸收体 被动调Q     

NaY(WO4)2∶Eu3+/Tb3+/Tm3+白色荧光粉的制备与发光性能

采用溶剂热法合成了一种单一相白色荧光粉NaY(WO4)2∶Eu3+,Tb3+,Tm3+。通过X射线衍射(XRD)、扫描电镜(SEM)、X射线能谱(EDS)及荧光光谱(PL)对制备的系列样品的物相、形貌和荧光性质进行了表征。结果表明:在荧光粉NaY(WO4)2∶x%Eu3+,4%Tb3+,1%Tm3+(x=5,10,15,20)中,随着Eu3+掺入量的增加,发光从绿光区进入白光区。同时观察到Tb3+到Eu3+的有效能量传递。     

9，10-二杂环取代蒽衍生物制备与三线态-三线态湮灭上转换性能研究

弱光上转换是基于三线态-三线态湮灭机制将低能量(长波长)的光转换为高能量(短波长)光的一种现象,是通过光敏剂与发光剂之间能量转移实现的。针对当前上转换体系中的光敏剂研究备受关注,而对于同等重要作用的发光剂的研究甚少的现状,利用Suzuki偶联反应制备了两个新的杂环取代蒽衍生物：9,10-二(3-呋喃)蒽(DFA)和9,10-二(3-噻吩)蒽(DTA)并通过结构表征;以9,10-二杂环取代蒽为发光剂、四苯基卟啉钯衍生物(PdTPPMe和PdTPPCOOH)为三线态光敏剂,研究所构成的光敏剂/发光剂双组分体系中,三线态-三线态能量转移效率(k_Q)、发光剂的延迟荧光寿命(τ_DF)及发光剂荧光量子产率(Φ_f)等因素对上转换效率(Φ_UC)的影响。结果表明,高效三线态-三线态能量效率(Φ_TTT)、快速延迟荧光寿命和大荧光量子产率将有利于提高上转换效率。进一步研究发现,含氧发光剂(DFA)与含羧基的光敏剂(PdTPPCOOH)之间可借助氢键发生有效耦合,有利于光敏剂与发光剂之间的三线态能量转移,导致弱光上转换效率显著提高。在半导体激光器(532 nm,70 mW·cm-2)激发下获得强的绿-转-蓝上转换效率最大可达10.11%。所获得的绿-转-蓝上转换荧光可使Pt/WO₃复合半导体受激;产生氧自由基并可促使香豆素转化为7-羟基香豆素。     

Cs(6PJ)与Ne、N2的碰撞精细结构混合和猝灭

在气体样品池条件下,研究了Cs（6PJ）（Ne、N2）碰撞能量转移过程。用调频半导体激光器激发Cs原子至Cs（6PJ）态,在不简的Ne或N2气压下,直接测量了6P3/2→6S1/2荧光和转移6P1／2、6S1／2荧光。