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11.
采用均相沉积法制备了不同Er3+离子浓度掺杂的Y2O3纳米晶, 应用XRD,SEM和PL光谱对该体系材料进行了表征.在Y2O3:Er3+纳米材料体系中, 观察和研究了Stokes及anti-Stokes PL谱强度与Er3+离子摩尔浓度变化的关系, 当Er3+离子浓度为2.0mol%时, anti-Stokes PL强度最强.粉末X
关键词:
氧化钇纳米晶
anti-Stokes PL
双光子吸收 相似文献
12.
We study the average property of the isospin effects of reaction mechanism induced by neutron-halo nuclei within the isospin-dependent quantum molecular dynamics model. We find that the extended neutron density distribution for the neutron-halo projectile brings an important isospin effect into the reaction mechanism, which induces the decrease of nuclear stopping R; however, it induces the obvious increases of the neutron-proton ratio of nucleon emissions (n/p)nucl for all of the beam energies in this work, compared to the same mass stable colliding system. 相似文献
13.
Zhu Hai-Liang Huang Pei Duan Chun-Ying Zheng Li-Min Liu Yong-Jiang Wu Mei-Fang Tang Wen-Xia 《Transition Metal Chemistry》1999,24(4):380-383
An azide-bridged polymeric cationic chain complex, [LCu2(N3)2]n(ClO4)2n
·n(H2O)**, where L=the dinucleating macrocyclic ligand bis-p-xylylBISDIEN, has been prepared and characterized by x-ray crystallography, u.v.-vis and i.r. spectra, and by magnetic measurements. The structure consists of cationic azide-bridged [LCu2(N3)2]2+ (unit) chains, non-coordinated perchlorate anions and crystallized water molecules. The azide anion is bound to two copper atoms in neighboring units with an end-to-end bridging mode. In each unit, the copper atoms have a different coordination geometry; Cu(1) is a four-coordinated, distorted square-planar geometry, whereas Cu(2) is a five-coordinated, distorted square-pyramid. The electronic spectra of the title complex differ in anhydrous and in aqueous MeCN solutions, indicating that dissociation and solvation occur in aqueous solutions. The characteristic i.r. absorptions of azides and perchlorates are described. Magnetic moments vary from 2.05 (B.M.) at 300K to2.01 (B.M.) at 80K, which suggests that very weak interactions exist between the metals. 相似文献
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Fe3O4/ chitosan magnetic microspheres of 50 to 80 滋m were prepared using the inverse phase emulsion dispersion and chemical crosslinking technology, and then modified with ethylenediamine for use in the adsorption of heavy metal ions. The adsorption properties of the modified Fe3O4/chitosan toward Cu2+, Cd2+ and Ni2+ were investigated. It was found that the adsorption capacities of Cu2+ and Ni2+ increased with pH, and a maximum adsorption for Cd2+ occurred at pH=3. The saturated adsorption capacities calculated by Langmuir isotherms were 54.3 mg·g-1 for Cu2+, 20.4 mg·g-1 for Cd2+, and 12.4 mg·g-1 for Ni2+, respectively. The adsorption kinetics were well described by pseudo-second-order equation models. The experimental results showed that the Fe3O4/chitosan modified with ethylenediamine presented higher adsorption selectivity for Cu2+ than for Cd2+ and Ni2+ in all studied pH ranges. 相似文献
17.
自碳纳米管被发现以来,由于其具有许多独特的电学、磁学、力学和气敏特性而引起了人们广泛的关注,在结构增强、纳米电子器件、场发射、储氢、传感器等众多领域具有非常广阔的应用前景,成为当前研究的热点之一[1,2].近年来,随着碳纳米管在传感器特别是气体检测领域研究的不断深入,碳纳米管为敏感材料的传感器已成功应用于对O2、NO2、NH3、H2等气体的检测研究[3],其中对NO2的检测可达到10×10-9(φ),但尚未见碳纳米管用于毒剂检测的报道.本文以碳纳米管作为石英晶体微天平膜材料,研究了碳纳米管的化学修饰方法及其对检测沙林的影响,结果表明经强酸加热氧化的碳纳米管对沙林响应大、解吸快、重复性好,可以作为传感器检测沙林的膜材料.该研究为碳纳米管在化学毒剂中的应用奠定了基础. 相似文献
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Many hydrogen-bonded liquids, especially glass-forming cases, display a dielectric relaxation behavior that differs qualitatively from that of other simple liquids. The majority of models aimed at explaining this unusual dielectric behavior associate the prominent Debye process with structural relaxation, viscous flow, and the glass transition. We perform dielectric and calorimetric studies of glass-forming mixtures of 2-ethylhexylamine and 2-ethyl-1-hexanol across the entire composition range. The kinetic glass transition temperature derived from the large dielectric Debye peak decreases, whereas that of the much smaller and asymmetrically broadened peak increases upon addition of amine. Only the latter feature coincides with the calorimetric glass transition results, implying that molecular structure and dielectric polarization fluctuate on time scales that can differ by orders of magnitude in many hydrogen-bonding liquids. 相似文献
20.
An efficient method has been developed for one-pot three-component coupling reactions of various aldehydes, 1-cyclohexen-2-one, and primary or secondary amines in the presence of a catalytic amount of Yb(OTf)3 under mild conditions to afford the corresponding 2-arylmethyl N-substituted anilines in good yields. In addition, the catalyst was easily recovered and could be reused for at least four cycles without any loss of activity. 相似文献