排序方式: 共有17条查询结果,搜索用时 15 毫秒
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Zhi-Chu Bi Yue-Ying Qian Xin-Li Zhao Shu-Yin Shen Jia-Yong Yu Hui-Jun XU H. Ti Tien 《Photochemistry and photobiology》1994,59(1):111-115
Abstract Zinc phthalolocyanine photosensitized donor-acceptor systems for light energy conversion and for the design of photoelectrochemical molecular devices are presented. Covalently linked phthalocyanine complexes were incorporated in bilayer lipid membranes (BLM) and deposited on SnO2 transparent electrodes. Their photovoltages were measured and compared. It has been found that a more favorable orientation and closer proximity are attained in the diad compounds between the donor (phthalocyanine)-acceptor (anthraquinone) pair than in the reference compound for efficient light-induced charge separation and transfer. The triad compound is the best among all tested compounds. The decrease in the fluorescence yield and lifetime induced by quinones was examined and the apparent electron-transfer rate constants were calculated. 相似文献
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一种可溶性氯铟酞菁化合物的光限幅性能研究 总被引:1,自引:0,他引:1
本工作通过无中心金属酞菁合成了可溶性金属酞菁化合物--四-α-(2-乙基丁氧基)氯铟酞菁,用纳秒脉冲激光在532 nm处检测了它在四氢呋喃溶液中的光限幅过程,发现该化合物具有非常明显的光限幅性能.在很低的入射光能量下,输出能量即开始偏离Beer定律,透过率随着入射光能量的增加迅速下降.这一效应归因于酞菁分子的反饱和吸收.通过纳秒激光闪光光解实验测定了上述化合物在四氢呋喃溶液中的瞬态吸收光谱及三线态寿命,实验结果表明在很宽的波长范围内分子具有较强的激发态吸收性能. 相似文献
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The mechanism of eosin-sensitized photoreduction of benzil with 1-benzyl-1,4-dihydronicotinamide — a model compound of NAD(P)H and the behavior of the excited states of eosin have been investigated. The effect of anthracene as a diffusion-controlled quencher of the photoreaction indicates that both excited triplet state and an unquenchable excited singlet state of eosin participated in the sensitized photoreaction. From the Stern-Volmer plot of quantum yield vs. anthracene concentration, the triplet reaction rate constant has been calculated to be 0.78 × 108 L M?1S?1 while the singlet reaction rate constant determined from quenching of eosin fluorescence by benzil is equal to 7.2 × 109 L M?1S?1. The singlet and triplet quantum yields are also determined to be 0.09 and 0.18 respectively. Since both the singlet and triplet energies of eosin are lower than that of benzil, energy transfer sensitization is not feasible. It is proposed that electron transfer from the excited eosin to benzil is responsible for the initiation. 相似文献
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TIAN Hong-Jian ZHOU Qing-Fu SHEN Shu-Yin XU Hui-Jun Institute of Photographic Chemistry Chinese Academy of Sciences Beijing China 《中国化学》1996,14(5):412-420
Photophysical properties of a porphyrin-phthalocyanine heterodimer covalently linked with a dipentoxy chain have been studied.Absorption spectra show that there is weak exciton coupling between the two chromophores in the ground state.Fluorescence spectra show that intramolecular energy transfer from porphyrin to phthalocyanine moiety occurs in competition with electron transfer.The efficiency of these two processes depends upon the mutual orientation of the two chromophores.The effect of solvent polarity on the intramolecular processes is also discussed. 相似文献
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为了寻找具有优异力学性能的新型超高温陶瓷材料, 结合进化算法和第一性原理, 系统研究了Hf-N二元体系所有稳定存在的化合物及其晶体结构. 除了实验已知的岩盐结构的HfN之外, 本文还找到了Hf6N(R-3), Hf3N(P6322), Hf3N2(R-3m), Hf5N6(C2/m)和Hf3N4(C2/m)五种新结构, 基于准简谐近似原理计算了这些稳定结构的声子谱以验证其动力学稳定性, 常温甚至更高温度下的吉布斯自由能以验证其高温热力学稳定性. 结果表明, 这些结构是动力学稳定的, 且在1500 K以下都是热力学稳定的. 同时, 本文还列出了在搜索过程中出现的空间对称性较高、能量较低的亚稳态结构, 包括Hf2N(P42/mnm), Hf4N3(C2/m), Hf6N5(C2/m), Hf4N5(I4/m), Hf3N4(I-43d)和Hf3N4(Pnma). 之后计算了上述所有结构的力学性质(弹性常数、体模量、 剪切模量、 杨氏模量、硬度), 随着N 所占比例的增加, 硬度呈现的整体趋势是先增大后下降, 在Hf5N6处取得最大值, 为21 GPa. 其中Hf3N2和Hf4N5也展现出了较高的硬度, 都为19 GPa. 最后, 计算了这些结构的电子态密度和晶体轨道汉密尔顿分布, 从电子结构的角度分析了力学性能的成因. 研究结果显示, 较强的Hf-N共价键和较低的结构空位率是Hf5N6具有优异力学性能的主要原因. 相似文献
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XIONG Guo-Xiang SHEN Shu-Yin YE Jian-Ping ZHOU Qing-Fu XU Hui-JunLaboratory of Photochemistry Institute of Photographic Chemistry Chinese Academy of Sciences Beijing China 《中国化学》1997,15(5):443-449
A novel zinc phthalocyanine containing four 17-crown-5 ether voids(17C5ZnPc) has been synthesized and characterized. UV-visible absorption and fluorescence emission spectra and as-sociated photophysical parameters have been determined. In contrast to most of the crown ether substituted phthalocyanines, no cofacial dimer formation is observed in the presence of alkali metal salts. In addition to the fluorescence at 710 nm from S1, a strong upper excited state (Soret 52) emission around 424 nm has been detected for the first time in the phthalocyanine series. Fluorescence decay of S1 and S2 emission can be analyzed by mono- and biexponential fits respectively. X-ray structure analysis showed that the crown ether unit is conformationally deformed and oblate that may account for the unusual spectroscopic properties. 相似文献
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Chih-Yu Chiu Shu-Yin Lai Chih-Jung Wang Yu-Ming Lin 《Journal of Radioanalytical and Nuclear Chemistry》1999,239(3):511-515
The distribution of137Cs in an undisturbed, multistoried, subtropical wet montane forest ecosystem surrounding Yuanyang Lake (lake surface level
ca. 1670m, in northeastern Taiwan), was investigated. The mossy forest here represents a currently-rare perhumid temperate
environment in subtropical region. The radioactivity concentration of137Cs was determined by γ-spectroscopy with a Ge(Li) detector. Although the soil is extremely acidic (pH 3.3 to 3.6) and the
rainfall is high,137Cs is evidently retained in the organic layer. The radioactivity concentration of137Cs in surface soil ranges from 28 to 71 Bq·kg−1. The concentrations of137Cs in the ground moss layer and litter were much lower than that in the soil organic layer, this suggests that137Cs detected is not from the newly deposited radioactive fallout. The radioactivity concentration and transfer factor (TF)
of137Cs varied with plant species. Shrubs and ferns have higher values than a coniferous tree (Taiwan cedar). The TF in this ecosystem
is as high as 0.21 to 1.88. The high values of TF is attributed to the abundance of the organic matter in the forest soils.
The rapid recycling of137Cs through the soil-plant system of this undisturbed multistoried ecosystem suggests the existence of an internal cycling
that help the accumulation of137Cs in this ecosystem. 相似文献