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41.
42.
溶液中分子的快速弛豫过程直接反映了溶液中溶质和周围溶剂分子间的相互作用[1-3].在液相体系中分子取向通常是随机分布的.当溶质分子被线偏振光激发至激发态时,其分子取向将由原来各向同性的球形分布瞬间变成各向异性的椭球分布.由于溶质分子周围大量溶剂分子的存在,通过二者之间相互作用,激发态溶质分子在一定方向上的取向优势将很快弛豫掉.这种溶液中的取向弛豫过程通常是几个到几百皮秒[1-3]. 相似文献
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44.
Peigeng Han Cheng Luo Songqiu Yang Yang Yang Prof. Dr. Weiqiao Deng Prof. Dr. Keli Han 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):12809-12813
Zero-dimensional (0D) lead-free perovskites have unique structures and optoelectronic properties. Undoped and Sb-doped all inorganic, lead-free, 0D perovskite single crystals A2InCl5(H2O) (A=Rb, Cs) are presented that exhibit greatly enhanced yellow emission. To study the effect of coordination H2O, Sb-doped A3InCl6 (A=Rb, Cs) are also synthesized and further studied. The photoluminescence (PL) color changes from yellow to green emission. Interestingly, the photoluminescence quantum yield (PLQY) realizes a great boost from <2 % to 85–95 % through doping Sb3+. We further explore the effect of Sb3+ dopants and the origin of bright emission by ultrafast transient absorption techniques. Furthermore, Sb-doped 0D rubidium indium chloride perovskites show excellent stability. These findings not only provide a way to design a set of new high-performance 0D lead-free perovskites, but also reveal the relationship between structure and PL properties. 相似文献
45.
本文报道紫膜在银胶上的表面增强共振拉曼散射与时间延迟、pH值的关系以及吸附对紫膜光化学循环的影响。在弱酸性pH条件下,紫膜和银胶混合3小时后才能看到分子—金属振动谱带。增强效应随pH值降低而加大,在pH3.8附近变化最明显。用488nm线激发。能分辨紫膜的M412和其他光化学循环中间体。pH3.8,M412的1567cm~(-1)特征振动带作为峰肩出现在变宽了的1536cm~(-1)带上,表明紫膜吸附在金属表面上并不阻断其光化学循环。pH2.7时,1567cm~(-1)带变得不明显,可能是M412的形成受到低pH值的限制。 相似文献
46.
4-(N,N-二乙氨基)水杨醛是染料及有机合成的重要中间体,也是具有亲水性质的生色团,其醛基常被用来制备席夫碱进而开发新颖的探针分子。本文介绍了对于一些常见离子如Al~(3+)、Cu~(2+)、Zn~(2+)、Hg~(2+)、Co~(2+)、F~-、CN~-等进行荧光识别和检测的基于4-(N,N-二乙氨基)水杨醛合成的席夫碱类荧光探针,这些探针具有较高的选择性和灵敏度,并有很好的细胞通透性和较低的细胞毒性,有一定的实用价值。本文为此类荧光探针在环境、生物、食品中的实际检测和应用研究提供了理论依据和实践基础。 相似文献
47.
Bin Yang Junsheng Chen Songqiu Yang Feng Hong Lei Sun Peigeng Han Prof. Dr. Tõnu Pullerits Prof. Dr. Weiqiao Deng Prof. Dr. Keli Han 《Angewandte Chemie (International ed. in English)》2018,57(19):5359-5363
Lead‐free perovskite nanocrystals (NCs) were obtained mainly by substituting a Pb2+ cation with a divalent cation or substituting three Pb2+ cations with two trivalent cations. The substitution of two Pb2+ cations with one monovalent Ag+ and one trivalent Bi3+ cations was used to synthesize Cs2AgBiX6 (X=Cl, Br, I) double perovskite NCs. Using femtosecond transient absorption spectroscopy, the charge carrier relaxation mechanism was elucidated in the double perovskite NCs. The Cs2AgBiBr6 NCs exhibit ultrafast hot‐carrier cooling (<1 ps), which competes with the carrier trapping processes (mainly originate from the surface defects). Notably, the photoluminescence can be increased by 100 times with surfactant (oleic acid) added to passivate the defects in Cs2AgBiCl6 NCs. These results suggest that the double perovskite NCs could be potential materials for optoelectronic applications by better controlling the surface defects. 相似文献
48.
Ca(1S0)+CH2Cl2、CHCl3和Ca(3P)+CH2Cl2、CHCl3反应的动态学研究 总被引:1,自引:0,他引:1
The reactions Ca(~1S_0)+ CH_2Cl_2, CHCl_3 and Ca(~3P)+ CH_2Cl_2, CHCl_3 were studied by means of the laser induced fluorescence (LIF). Systematic simulation of the observed LIF spectra revealed that change of the Ca atoms from the ~3p states to the ~1S_0 state brought about a decrease of the fraction of total energy going to the ground state CaCl product vibration and an increase of the fraction of total energy going to the ground state CaCl product rotation. Total cross sections for the reactions of Ca(~1S_0)+CH_(4-n)Cl_n(n=2, 3) and the fraction of the Ca atoms going to the ~3P states in the discharge Ca beam were estimated from the LIF indensity of the CaCl product and total cross sections for the reactions Ca(~3P)+CH_(4-n)Cl_n. They are 0.39±2 nm, 0.45±2 nm, 1.8+0.1%, respectively. 相似文献
49.
Photochromic diarylethenes have been widely used in many fields. However, their cyclization process must be induced by UV light. In this article, a simple strategy is developed by extending π-conjugation with electron donating groups. The modified dirylethene derivative can photocyclolize under 405-nm light with a good photochromic efficiency. Meanwhile, its absorption and moderate fluorescence can be switched effectively in both directions by visible lights(405 and 520 nm, respectively) in different solutions and in living cells. We believe that this simple method will become a versatile strategy for developing various dirylethylenes with visible-light photochromism. 相似文献
50.
Zhang L Ren T Wang H Wang M Yang C Han K 《The journal of physical chemistry. B》2006,110(46):23395-23402
The reaction of acrylonitrile with the C(001)-2 x 1 surface has been investigated by employing density functional cluster model calculations. The calculations revealed eight possible reaction pathways for acrylonitrile with the surface dimer. Full geometry optimized structures were obtained for all adducts, including intra- and interdimer reaction products. These results were analyzed in terms of both the total energy values and the detailed optimized geometries. We find that the reaction of acrylonitrile with the diamond (001) surface occurs primarily through its nonpolar C=C group and the intradimer [2+2](cc) product is the dominant product. All these results are in good agreement with the experimental work by Schwartz. It is noteworthy that the isomerization process plays an important role in the chemisorption process. Both intradimer [4+2] product and interdimer [2+2](cc) product can isomerize to the intradimer [2+2](cc) product. The present study shows that the isomerization between intradimer [4+2] product and intradimer [2+2](cc) product is slightly favorable over the direct path to formation of the intradimer [2+2](cc) product. 相似文献