Quenching of fluorescence of conjugated poly(p-phenylene) polymers by benzil and dimethylaminobenzil molecules

We have studied the mechanisms for quenching of the fluorescence of conjugated poly(p-phenylene) polymers by benzil and dimethylaminobenzil molecules. We have shown that molecules in the diketone series are quenching agents for the fluorescence of the indicated polymers, and can serve as singlet-triplet converters capable of populating the triplet state of the polymer. We have observed that the efficiency of quenching of the fluorescence of the studied polymers depends considerably on the presence of bulky side groups in the polymer or in the activator molecules. Based on analysis of the data obtained, we conclude that in the case of a rigid planar structure for the polymer, a significant contribution to quenching of its fluorescence comes from not only singlet-singlet energy transfer but also charge transfer, leading to formation of intermolecular complexes (exciplexes). __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 756–762, November–December, 2006.     

THE INTERACTION OF ETHYL BENZOATE AND TRIFLUOROACETIC ACID IN EXCITED STATE

This paper is concerned with the interaction of ethyl benzoate (EBA) and trifluoroaceticacid (TFA) molecules in the excited state by measurements of steady--state and transient fluo-rescence spectra at room and low temperatures. The results show that not only the 1:1 exci-plex but also the 2:1 triplex between EBA and TFA was formed. The formation pathway ofthe triplex is that the exciplex formed at first, then by the interaction with the EBA mole-cule it transformed into triplex. But it could not be formed by the dimer of EBA by interac-tion with TFA. The dimer of EBA is confirmed in the concentrated solution. So there arefour components in EBA/TFA--concentrated solution and their fluorescence lifetimes aremeasured respectively.     

粒子等离子共振对有机半导体共混体系中激发复合体荧光发射的作用

研究了具有局域等离子共振特性的金纳米岛状结构阵列对高分子材料共混体系中激发复合体荧光发射特性的影响.实验结果表明,当粒子等离子共振发生在激发复合体荧光光谱区时,其荧光发射的强度得到了显著增强,且荧光寿命也得以延长.可以认为,粒子等离子共振诱发的局域场增加了激子的扩散距离,利于在相分离界面处激发复合体的形成. 关键词： 金纳米岛状结构 粒子等离子共振局域场增强效应 聚合物共混体系 激发复合体     

Novel Transient Species of DNA Bases From Laser Photolysis

The laser photochemistry and photosensitization of DNA bases were carried out by using a nanosecond kinetic spectroscopy. A novel triplet state of thymine and its OH adduct were observed in N_2 and N_2O saturated aqueous solution respectively. The transient absorption spectra of triplet cytosine, cytidine and deoxycytidine monophosphoric acid were observed for the first time. Triplet guanosine was confirmed and its pK, value, 8.7, was obtained. Kinetic studies of the growth-decay of the above transient species were performed and their reaction mechanisms were elucidated in detail.     

稀土有机光伏器件

采用真空气相沉积法制备了结构为ITO／TPD／Gd(DBM)3bath／Mg：Ag的双层结构有机光伏器件，其中，TPD为受体，Gd(DBM)3bath为给体。在4mW／cm^2的365nm波长紫外光从IT0玻璃方向垂直照射下，器件的开路电压Voc，短路电流Isc和填充因子FF分别为3．2V，29．24μA／cm^2，0．286。在实验中发现器件的外量子效率的光谱响应曲线与TPD的吸收光谱曲线基本一致，在紫外光照射下TPD／Gd(DBM)3bath膜层的界面处产生的激基复合物在光伏过程中扮演着至关重要的角色。     

有机电致发光器件中界面激基复合物的形成

在ITO／TPD／PBD／Al双层器件中，电致发光光谱相对于TPD和PBD的荧光光谱有明显的红移。根据对TPD、PBD和TPD：PBD等量混蒸膜的PL激发光谱及电致发光光谱的研究，认为在TPD和PBD的界面产生了激基复合物。另外，该器件发射光谱既有TPD的成分也有激基复合物的成分，并且随着电流的改变，两者的相对强度发生变化。在电流密度增大时，峰值波长向长波方向移动，器件发光颜色由白光变为黄绿光。根据器件能级关系，说明了相关的现象。     

铕配合物OEL器件中激基复合物发光机制及消除

有机电致发光无论在科学研究还是在实际应用上都极大地吸引了人们的兴趣[1～3]。在研究的过程中,人们开发了许多的有机电致发光材料,在众多的材料中,稀土配合物有着明显的优势:由于稀土配合物能够利用配体三重态的能量,使得它的内量子效率在理论上能达到100%,而其它材料除了磷光染料[4,5]外内量子效率只能达到25%,同时稀土配合物中心离子的窄带发射有利于全色显示。目前,在有机电致发光领域实现高效纯红的窄带发光是一个很大的挑战,因为在基于颜色叠加原理的全色显示中,获得纯的红色发光是至关重要的。而三价稀土配合物中铕离子的红色发…     

STUDY ON THE PROTONATION MECHANISM OF 2,6-DIMETHYL NAPHTHALENE DICARBOXYLATE

By the study of absorption and fluorescence spectra and the lifetime of fluorescence at room and low temperatures of 2,6-dimethyl naphthalene dicarboxylate (DMN) in different concentrations of sulfuric acid, different interactions between molecules of DMN and sulfuric acid have been observed. These interactions have been revealed by the absorption spectra of charge transfer complex in the ground state, emission of exciplex, absorption spectra of hydrogen bonding interaction, absorption and emission spectra after proton transfer and different lifetimes before and after protonation. The interaction mechanism of DMN and sulfuric acid through first the CT complex and exciplex then hydrogen bonding and finally proton transfer is proposed.     

无色孔雀绿光氧化反应的途径

前一篇文章已说明,无色孔雀绿(LMG)经光氧化生成孔雀绿(MG⁺)染料是一个复杂的光化学过程。萘加入反应溶液猝灭了LMG的激发态,但却使反应速率升高。对这一实验结果我们曾推断为:可能是由于萘与LMG之间发生了电子转移作用。本文将对这一推断作进一步实验论证,并将说明在没有电子受体参加时,LMG的光氧化主要通过其激发三线态途径进行。已得到的实验结果证明,我们的上述推断是正确的,现予以报道。     

胆固醇酯类化合物在混合溶剂中的簇集及其荧光光谱的特征

近年来,人们对长链脂肪族、芳香族化合物分子在二甲基亚砜/水(DMSO/H₂O)混合溶剂中发生簇集,形成聚集体进行了广泛研究指出:簇集的驱动力是疏水作用。