共查询到20条相似文献,搜索用时 78 毫秒
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对位取代苯磺酸钠在溶液及界面的光反应研究 总被引:1,自引:0,他引:1
用自旋捕捉-ESR方法研究了对位取代苯磺酸在水溶液中光化学行为,结果表明pH的改变及半导体胶体的存在都能影响其光解过程,使产生的中间体发生变化,发生光解过程中产生的中间体之一是硫中心自由基SO^-3,在一定的pH范围还有C中心自由基和氢自由基生成,在较低pH范围,初始反应速率与pH值呈指数关系。 相似文献
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共轭聚合物中稳定自由基的ESR研究 总被引:2,自引:2,他引:2
通过ESR跟踪测试,研究了3种胺类化合物与聚(N,N-二甲基苯胺)(PDMA)中离域正离子自由基相线作用的过程,发现胺类化合物能使PDMA的ESR谱形发生不同程度的劈裂,信号强度随时间的变化与胺的结构有关,说明正离子自由基与亲核试剂作用后发生了定域化转变,通过进一步比较发现PDMA自由基的亲电活性不如聚苯上的正离子的自由基。 相似文献
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香烟烟雾中自由基的检测 总被引:7,自引:0,他引:7
祁俊生 《理化检验(化学分册)》2001,37(8):364-366
对香烟焦油中的Q/H2Q自由基及气相中的自由基进行了测定,同时对香烟燃烧产生自由基的机理进行了探讨。 相似文献
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人体胃癌组织中含铁络合物的ESR谱 总被引:1,自引:0,他引:1
人体胃癌组织中含铁络合物的ESR谱郑莹光,王萍,于小林,赵吉生(吉林大学分析测试中心,长春,130023)(白求恩医科大学第三临床医院)关键词胃癌组织,ESR,铁络合物ESR技术已广泛用于生物体内自由基的研究[1,2]但用来直接检测人体癌变组织中金属... 相似文献
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三种含硒环糊精的SeGPX活力及对HO·的清除作用 总被引:6,自引:3,他引:3
报道了3种硒代β-环糊精作为SeGPX模拟物的活力,并初步探讨了硒环糊精的结构与活力的关系。利用Fenton反应产生的羟基自由基与苯甲酸钠反应生成的具有荧光的羟基苯甲酸间接测定羟基自由基的含量。结果表明,3种含硒环糊精对HO·的生成均无明显的抑制作用。 相似文献
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应用ESR技术对一变质系列煤的自由基特性进行了实验研究,探讨了煤中自由基的起源、性质和数量的变化,并将其与煤的大分子结构相关联。结果表明,煤自由基特性在煤化过程中的规律性较好。 相似文献
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Wendelin Bücking Salam Massadeh Alexei Merkulov Shu Xu Thomas Nann 《Analytical and bioanalytical chemistry》2010,396(3):1087-1094
Low toxic InP/ZnS quantum dots (QDs), ZnS:Mn2+/ZnS nanocrystals and CdSe/ZnS nanoparticles were rendered water-dispersible by different ligand-exchange methods. Eventually,
they were coated with bovine serum albumin (BSA) as a model protein. All particles were characterised by isotachophoresis
(ITP), laser Doppler velocimetry (LDV) and agarose gel electrophoresis. It was found that the electrophoretic mobility and
colloidal stability of ZnS:Mn2+/ZnS and CdSe/ZnS nanoparticles, which bore short-chain surface ligands, was primarily governed by charges on the nanoparticles,
whereas InP/ZnS nanocrystals were not charged per se. BSA-coated nanoparticles showed lower electrophoretic mobility, which
was attributed to their larger size and smaller overall charge. However, these particles were colloidally stable. This stability
was probably caused by steric stabilisation of the BSA coating. 相似文献
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ZnS/CdS/ZnS quantum dot quantum well was prepared. The optical properties of ZnS/CdS/ZnS QDQW with different thickness of CdS well and ZnS shell were studied. Absorption spectra, emission spectra, and luminescence lifetimes were measured. The observed luminescence was assigned to the bulk donor-acceptor pair recombination of CdS and can be enhanced by increasing the thickness of the CdS well or coating an appropriate thickness of ZnS shell on the surface of the CdS well. The luminescence enhancement was caused by the relative reduce in the surface effect. The luminescence lifetimes were influenced strongly by the surface state. 相似文献
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High-quality ZnS, ZnS:Mn2+, and ZnS:Mn2+/ZnS (core/shell) nanocrystals (NCs) were synthesized via a high-boiling solvent process and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectra. The monodisperse ZnS NCs (size = 8 nm), which self-assembled into several micrometer-sized domains, were achieved by adopting poly(ethylene glycol) (PEG) in the reaction process (without using a size-selection process). The obtained ZnS:Mn2+ and ZnS:Mn2+/ZnS core/shell NCs are highly crystalline and quasimonodisperse with an average particle size of 6.1 and 8.4 nm, respectively. All of the as-formed NCs can be well dispersed in hexane to form stable and clear colloidal solutions, which show strong visible emission (blue for ZnS and red-orange for ZnS:Mn2+ and ZnS:Mn2+/ZnS) under UV excitation. The growth of a ZnS shell on ZnS:Mn2+ NCs, that is, the formation of ZnS:Mn2+/ZnS core/shell NCs, resulted in a 30% enhancement in the PL intensity with respect to that of bare ZnS:Mn2+ NCs due to the elimination of the surface defects. 相似文献
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Li C Jiang D Zhang L Xia J Li Q 《Langmuir : the ACS journal of surfaces and colloids》2012,28(25):9729-9734
Novel ZnS quantum dots (QDs) and ZnS quantum flakes (QFs) were successfully prepared with graphene nanosheets (GNs) as a special template, and two unique heterostructures of ZnS/GNs were also obtained. Due to the structure-directing template effect of GNs, the as-synthesized ZnS with different morphologies, dots or flakes, were uniformly distributed on the surface of GNs by controlling nucleation and growth. The two different heterostructures of ZnS/GNs exhibited obvious photovoltaic response, and ZnS/GN QFs-on-sheet heterostructures show higher photovoltage than that of ZnS/GN QDs-on-sheet. 相似文献
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Ordered heterojunction nanocap arrays composed of the bilayer film Ag/ZnS were prepared onto ordered two-dimensional polystyrene bead arrays by magnetron control sputtering, and the surface morphologies were tuned by changing the ZnS thickness. When the ZnS thickness varied from 10 to 30 nm with a Ag thickness of 5 nm, the roughness of the bilayer film Ag/ZnS increased obviously. The UV–VIS spectra showed the shifted LSPR peaks with ZnS thickness, which was attributed to the changes of the electron density as confirmed by Hall effect analysis. SERS observations confirmed the charge transfer process for the varied electromagnetic couplings when the ZnS thickness changed. 相似文献
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Wentao Zhang Hong-Ro Lee 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1623-1631
Methacrylic acid (MAA) was used as a manganese carrier to prepare ZnS/MAA-Mn particles, and ZnS/ZnS:Mn phosphors were formed from ZnS/MAA-Mn by ion substitution through heat treatment. After silica coating on surface by chemical precipitation method with tetraethyl orthosilicate (TEOS), ZnS/ZnS:Mn/SiO2 phosphors were prepared successfully as a new core/shell structure compound. The thickness of layers was controlled by adjusting concentrations of manganese (II) acetate (Mn(CH3COO)2) and TEOS. Structure, morphology, and composition of prepared phosphors were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS), respectively. Photoluminescence (PL) properties of ZnS with different Mn2+ content were analyzed by PL spectrometer. PL emission intensity and PL stability were analyzed for evaluating effects of silica coating and Mn2+ activator doping. As a result, the structure of two layers could be observed, and optimum composition of ZnS/ZnS:Mn/SiO2 structure was also obtained. 相似文献
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Single-crystalline ZnS nanowires coated with graphitic carbon shells were synthesized by thermal evaporation of a mixture of ZnS and SnS powders in a graphite crucible. As-synthesized ZnS/C nanostructures were characterized using X-ray diffraction, scanning electron microscope, and transmission electron microscopy equipped with an energy-dispersive X-ray spectrometer. The ZnS core nanowires were formed by a Sn-catalytic vapor-liquid-solid process and grew along the [210] directions. Photoluminescence spectrum reveals that the carbon-coated ZnS nanowires have a strong emission band centered at 586 nm and a shoulder band at 645 nm. 相似文献
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We reported controllable synthesis of ZnS nanocrystal-polymer transparent hybrids by using polymethylmethacrylate (PMMA) as
a polymer matrix. In a typical run, the appropriate amounts of zinc chloride (ZnCl2) and sodium sulfide (Na2S) in the presence of 2-mercaptoethanol (ME) as the organic ligand were well dispersed in H2O/dimethylformamide solution without any aggregation. In addition, the Mn-doped ZnS nanocrystals (NCs) were synthesized with
similar method. Then, ZnS-PMMA hybrids were obtained via free radical polymerization in situ by using ZnS NCs functionalized
with methacryloxypropyltrimethoxysilane (MPS). FT-IR characterization indicates the formation of robust bonding between ZnS
NCs and the organic ligand. The TEM images show that ZnS NCs are well dispersed in PMMA matrix, and particle size of as-prepared
ZnS NCs is about 2.6 nm, in agreement with the computing results of Brus’s model and Debye–Scherrer formula. The photoluminescence
measurements present that ZnS NCs, Mn-doped ZnS NCs, and ZnS/PMMA hybrid show good optical properties. 相似文献