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71.
R. Pizzoferrato L. Lagonigro T. Ziller A. Di Carlo R. Paolesse F. Mandoj A. Ricci C. Lo Sterzo 《Chemical physics》2004,300(1-3):217-225
We study the infrared emission at 1.54 μm of an organolanthanide complex, Er(III)-tetraphenylporphyrin [Er(TPP)acac], both as a result of direct optical excitation and via energy transfer from host π-conjugate polymers of type poly(arylene–ethynylene) [PAE]. In the first case, the emission of the neat complex is characterized in inert transparent materials and a value of the quantum yield at 1.54 μm φIR=4×10−4 is measured. Then, fluorescence resonance transfer is investigated in blends of Er(TPP)acac with PAEs by monitoring the quenching of the polymer fluorescence along with the enhancement of both the visible emission of the ligand and the near-infrared band of Er3+. These different procedures allow a detailed analysis of the transfer efficiency within a specific implementation of the Förster model for polymeric donors. The experimental values of the critical radius R0, ranging from 1.3 to 2.5 nm for the different blends, are in good agreement with theory for a wide interval of the physical and spectroscopic parameters. This suggests that other mechanisms for excitation transfer do not play a significant role in these materials. 相似文献
72.
Resistivity-temperature characteristics of sol gel YBa2Cu3Oy samples synthesized in flowing oxygen atmosphere 下载免费PDF全文
The relationship of resistivity versus synthesizing temperature of sol gel YBa_2Cu_3O_y samples was studied when prepared under flowing oxygen conditions. A set of high-temperature ρ-T curves was obtained for the whole process. After the sample finished the test measuring, its resistivity was ρ_{300}=9.83×10^{-3 }Ω·cm at room temperature. The ρ-T curve also showed that the orthorhombic-tetragonal phase transformation of sol-gel YBa_2Cu_3O_y sample occurred at 581℃ for the sample in the rising temperature process, but at 613℃ in the cooling process, lower than that of the samples made by using the conventional powder metallurgy methods. 相似文献
73.
Solid state nuclear track detectors are commonly used for measurements of concentrations of radon gas and/or radon progeny. All these measurements depend critically on the thickness of the removed layer during etching. However, the thickness of removed layer calculated using the etching period does not necessarily provide a sufficiently accurate measure of the thickness. For example, the bulk etch rate depends on the strength of stirring during etching for the LR 115 detector. We propose here to measure the thickness of the removed layer by using energy-dispersive X-ray fluorescence spectrometry. In the present work, a reference silver nitrate pellet is placed beneath the LR 115 detector, and the fluorescence X-ray intensity for silver is then measured. We have found a linear relationship between the X-ray intensity and the thickness of the removed layer for LR 115 detector. This provides a fast method to measure the thickness of removed layer from etching of LR 115 detector. However, this method was found to be inapplicable for the CR-39 detector. Therefore, alternative methods have yet to be explored for the CR-39 detector. 相似文献
74.
We have simultaneously used adsorption isotherm volumetry and Fourier transform infrared spectroscopy in order to take the investigations on amorphous ice structure a step further, especially concerning porosity and annealing-induced modifications. We have studied surface reorganization during annealing and found that the number of surface sites decreases before crystallization, their relative ratios being different for amorphous and crystalline ice. We also present results confirming that ice can have a large specific surface area and nevertheless be non-microporous. 相似文献
75.
Characterizations of Tb:Zn2SiO4 films on silicon wafer prepared by sol-gel dip-coating and solid-phase reaction 下载免费PDF全文
Terbium-doped Zn_2SiO_4 films were successfully prepared on Si wafers by a simple sol-gel dip-coating and solid-phase reaction method of ZnO and SiO_2. X-ray diffraction (XRD) and UV-Vis absorption results revealed that films processed below 850℃ were ZnO in wurzite structure, and films processed above 850℃ were Zn_2SiO_4 in wellimite structure. Photoluminescence measurements of the Tb-doped Zn_2SiO_4 films showed two strong emission bands at 490 and 545nm. The photoluminescence lifetime was 4.6ms. 相似文献
76.
77.
使用结构简单的单温炉设备,通过三步升温热解二茂铁、三聚氰氨混合物方法,在二氧化硅、多晶陶瓷基底上分别合成了碳纳米管阵列、碳纳米管捆束.使用扫描电子显微镜、透射电子显微镜、电子能量损失谱和x射线光电子能谱对合成样品进行了结构和成分分析.结果显示:两种基底上合成的纳米管均为多壁纯碳管;生长于光滑二氧化硅表面的碳纳米管具有高度取向性和一致的外径,长度为10—40μm.碳纳米管采取催化剂顶端生长模式并展示出类杯状形貌;生长于粗糙多晶陶瓷表面的碳纳米管捆束随机取向,碳纳米管直径为15—80nm,长度在几百微米,展示
关键词:
碳纳米管
热解法
三步升温工艺 相似文献
78.
Vytautas Getautis Maryte Daskeviciene Tadas Malinauskas Vygintas Jankauskas 《Monatshefte für Chemie / Chemical Monthly》2007,28(5):277-283
Synthesis of a new monomer and polymer containing both ferrocene and hydrazone moieties are reported. The obtained materials
were examined by various techniques including differential scanning calorimetry, UV, IR, NMR spectroscopy, and time of flight
method. These materials may be of particular interest for the development of future electrophotographic photoreceptors as
electron photoemission spectra of the layers showed ionization potentials of 5.35–5.41 eV. The hole drift mobility values
in compositions of the designed structures with bisphenol Z polycarbonate exceeded 10−8 cm2/Vs at strong electric fields. 相似文献
79.
Azizollah Habibi Leyla Mousavifar Issa Yavari Mohammad R. Yazdanbakhsh 《Monatshefte für Chemie / Chemical Monthly》2007,4(8):603-606
Alkyl isocyanides undergo a smooth reaction with alkylidene Meldrum’s acids in the presence of arylhydroxylamines to produce N
1-alkyl-2-(3,5-dioxo-2-aryltetrahydro-4-isoxazolyl)alkanamides in high yields. 相似文献
80.
N. A. Anurova V. A. Blatov G. D. Ilyushin O. A. Blatova A. K. Ivanov-Shitz L. N. Demyanets 《Crystallography Reports》2008,53(6):930-936
A new method was developed for studying voids and channels in crystal structures based on the Voronoi-Dirichlet partition
of crystal space, and 822 structurally characterized ternary compounds Li
p
X
q
O
r
were analyzed for the first time. For these compounds, the dimensionality was determined and the migration patterns of channel
systems capable of providing lithium-ion transport were constructed. The calculated coordinates of lithium atoms in the centers
of the voids are consistent (within 0.4 ?) with the known structural data. Among these compounds, 113 compounds have infinite
channel systems, 60 compounds (18 structural types, STs) have been described earlier in the literature as solid electrolytes,
and 53 compounds (23 STs) can be considered as potential one-, two-, or three-dimensional ionic conductors (13, 3, and 7 STs,
respectively).
Original Russian Text ? N.A. Anurova, V.A. Blatov, G.D. Ilyushin, O.A. Blatova, A.K. Ivanov-Shitz, L.N. Dem’yanets, 2008,
published in Kristallografiya, 2008, Vol. 53, No. 6, pp. 987–993. 相似文献