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1.
Early stages of rare-earth metal (Yb and Eu) growth on a vicinal, single-domain Si(1 0 0)2 × 1 surface have been studied in the coverage range of 0.1-0.3 monolayer (ML) by low energy electron diffraction, scanning tunneling microscopy, and synchrotron radiation photoemission spectroscopy. We show that Yb induces the 2 × 3 periodicity in the whole range of coverage studied. The 2 × 3 reconstruction coexists with the local 3 × 2/4 × 2 structure at about 0.2 ML of Yb. In contrast, Eu forms the 3 × 2 periodicity at 0.1-0.2 ML, whereas this structure is converted into the 2 × 3 phase at about 0.3 ML. The atomic arrangement and electronic properties of these reconstructions and the adsorbate-mediated modification of surface morphology are investigated. 相似文献
2.
Tuomas Aitasalo Jorma Hls Hgne Jungner Jean-Claude Krupa Mika Lastusaari Janina Legendziewicz Janne Niittykoski 《Radiation measurements》2004,38(4-6):727-730
The UV excited and persistent luminescence properties as well as thermoluminescence (TL) of Eu2+ doped strontium aluminates, SrAl2O4:Eu2+ were studied at different temperatures. Two luminescence bands peaking at 445 and 520 nm were observed at 20 K but only the latter at 295 K. Both Sr-sites in the lattice are thus occupied by Eu2+ but at room temperature efficient energy transfer occurs between the two sites. The UV excited and persistent luminescence spectra were similar at 295 K but the excitation spectra were different. Thus the luminescent centre is the same in both phenomena but excitation processes are different. Two TL peaks were observed between 50 and 250 °C in the glow curve. Multiple traps were, however, observed by preheating and initial rise methods. With longer delay times only the high temperature TL peak was observed. The persistent luminescence is mainly due to slow fading of the low temperature TL peak but the step-wise feeding process from high temperature traps is also probable. 相似文献
3.
以PCl3为脱水剂,将邻氨基硫酚与水杨酸脱水环化合成出2-(2-羟基苯基)苯并噻唑,并进一步将所得产物与乙酸锌反应合成出2-(2-羟基苯基)苯并噻唑螯合锌(Zn(BTZ)2)材料。以该配合物作为发光层制备出结构为ITO/PVK:TPD/Zn(BTZ)2/Al近白色电致发光器件,其色坐标位于白场之内(x=0.242,y=0.359),在驱动电压为16V时,亮度达3200cdm2,对应的量子效率为0.32%。进一步在Zn(BTZ)2中掺入橙红色染料Rubrene,制成ITO/PVK:TPD/Zn(BTZ)2:Rubrene/Al结构器件,实现了纯白色发光(色坐标值:x=0.324,y=0.343),非常接近于白色等能点,且量子效率达0.47%。最后对上述器件的发光和电学性能进行了深入的研究和探讨。 相似文献
4.
Several functionalized β-diketones and their europium complexes have been synthesized and characterized. The UV-Vis absorption, photoluminescent spectra, thermal and electrochemical properties of these complexes were investigated. The thermal analysis shows that the complexes have good thermal stability. By introducing the number of extended phenyl rings we succeeded in obtaining europium complexes with extremely high photoluminescent quantum yield (PLQY) in solution due to strong site isolation effect. 相似文献
5.
New Schiff bases of 2,4‐dihydroxybenzaldehyde with siloxane‐α,ω‐diamines having different numbers of siloxane units in the chain have been synthesized and characterized by spectroscopy, elemental and thermal analyses. These azomethines were found to form complexes readily with copper(II), nickel(II), cobalt(II), cadmium(II) and zinc(II). From IR and UV–Vis studies, the phenolic oxygen and imine nitrogen of the ligand were found to be the coordination sites. Thermogravimetric analysis (TGA) data indicate the chelates to be more stable than the corresponding ligands. The melting points increase with shortening of the siloxane segment from azomethine, as well as the result of complexation. The chelates obtained were covalently inserted in polymeric linear structures by polycondensation through the OH‐difunctionalized ligand with 1,3‐bis(carboxypropyl)tetramethyldisiloxane. Direct polycondensation, assisted either by acetic anhydride or N,N′‐dicyclohexylcarbodiimide as dehydrating agent and the complex 4‐(dimethylamino)pyridinium 4‐toluenesulfonate as catalyst, was used for the synthesis of these compound types. The structures of the polymers obtained were confirmed by IR, UV and 1H NMR. Characterization was undertaken by TGA, solubility tests and viscosity measurements. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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7.
I. P. Romanova S. G. Fattakhov A. A. Nafikova I. I. Vandyukova R. R. Shagidullin N. M. Azancheev V. S. Reznik O. G. Sinyáshin 《Russian Chemical Bulletin》1998,47(9):1812-1819
The reactions of phosphine derivatives of diallyl isocyanurates with palladium(ii) dichloride lead to the formation of complexes, whose structure, composition, and stability depend on the length of the methylene
chain between the isocyanurate and diphenylphosphine fragments in the ligand. 1,3-Diallyl-5-[5′-(diphenylphosphino)pentyl
and 10′-(diphenyl-phosphino)decyl] isocyanurates with PdCl2 form monomeric L2PdCl2
trans-complexes in which P atoms of the ligands participate in coordination with the metal. 1,3-Diallyl-5-[2′-(diphenylphosphino)ethyl]
isocyanurate with PdCl2 forms a dimeric (LPdCl2)2 complex, which decomposes in a solution to the monomer including solvent molecule into the coordination sphere of the metal.
The reactions of 1,3-diallyl-5-[4′-(diphenylphosphino)butyl] isocyanurate and 1,3-diallyl-5-[6′-(diphenylphosphino)hexyl]
isocyanurate with PdCl2 give monomeric chelate LPdCl2 complexes in which one of the allyl groups of the isocyanurate cycle participates in coordination with the central ion along
with the phosphorus atom.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1859–1865, September, 1998. 相似文献
8.
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10.
L. S. Vasil'ev O. G. Azarevich V. S. Bogdanov M. N. Bochkareva V. A. Dorokhov 《Russian Chemical Bulletin》1992,41(11):2104-2107
Boron chelates were obtained by the reaction of butoxy(butylthio)diphenylborane with 5,5,5-trifluoro(trichloro)-4-aminopent-3-en-2-one, and their reactions with primary amines were investigated. -Diiminate complexes of boron with trifluoro- and trichloromethyl groups were synthesized.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2657–2661, November, 1992. 相似文献