排序方式: 共有21条查询结果,搜索用时 171 毫秒
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研究了纳米银对稀土铕-吡啶-2,6-二羧酸配合物(Eu(Ⅲ)C7H5NO4,Eu(Ⅲ)DPA)的荧光性质的影响。随着纳米银浓度增加,荧光强度先增强而后逐渐下降。较大粒径的纳米银使Eu(Ⅲ)DPA荧光增强效率较大,且达到最大荧光增强效率所需的纳米银浓度较低。在高浓度Eu(Ⅲ)DPA溶液体系中,纳米银导致荧光猝灭。电偶极子跃迁发射荧光增强效率大于磁偶极子跃迁发射荧光增强效率。分析认为,纳米银对Eu(Ⅲ)DPA荧光性质的影响与表面等离子体共振与激发态荧光中心强烈耦合以及表面等离子体再吸收有关。同时,纳米银对铕配合物的不对称率有影响,其影响因素与局域电磁场增强,折射率以及配位场有关。 相似文献
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本文研究了纳米银对稀土铕-吡啶-2,6-二羧酸配合物(Eu(Ⅲ)C7H5NO4,Eu(Ⅲ)DPA)的荧光性质的影响。随着纳米银浓度增加,荧光强度先增强而后逐渐下降。较大粒径的纳米银使Eu(Ⅲ)DPA荧光增强效率较大,且达到最大荧光增强效率所需的纳米银浓度较低。在高浓度Eu(Ⅲ)DPA溶液体系中,纳米银导致荧光猝灭。电偶极子跃迁发射荧光增强效率大于磁偶极子跃迁发射荧光增强效率。分析认为,纳米银对Eu(Ⅲ)DPA荧光性质的影响与表面等离子体共振与激发态荧光中心强烈耦合以及表面等离子体再吸收有关。同时,纳米银对铕配合物的不对称率有影响,其影响因素与局域电磁场增强,折射率以及配位场有关。 相似文献
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通过吸收光谱和荧光光谱等手段研究了正/负电性纳米银对不同pH值的甲基橙(MO)溶液光谱学性质的影响.研究结果表明,正电性纳米银(P-Ag)与甲基橙作用形成新的复合物,吸收光谱表现为复合物体系的性质.负电性纳米银(N-Ag)与甲基橙静电排斥作用,相互作用较弱,吸收光谱仅表现为两者简单叠加.在正电性纳米银-甲基橙体系中,S1→S0荧光明显增强.当溶液pH=2.1时,荧光增强比率最大,当pH=4.8时,荧光增强比率最小;S2→S0荧光减弱,且与体系的pH值关系不大.在负电性纳米银-甲基橙体系中,仅少量纳米银存在条件下,S1→S0荧光略增强.在溶液pH=2.1时,荧光增强比率最大;S2→S0荧光明显减弱,且与体系的pH值关系不大.分析认为,不同电性的纳米银对甲基橙光谱学性质影响不同,与纳米银与甲基橙分子间相互作用、纳米银的局域场增强效应以及无辐射能量转移作用等密切相关. 相似文献
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Stable aqueous dispersive colloidal Ag nanoparticles were prepared by reducing silver nitrate with sodium borohydride in the presence of 3-mercaptopropionic acid. The formation process of the Ag nanoparticles was investigated by UV-Visible spectroscopy and transmission electron microscopy. The results show that the spherical and rodlike particles and aggregates are formed in the initial stage of the reaction, then the rodlike particles and aggregates are gradually decomposed into small spherical particles, and the final obtained Ag nanoparticles with an average size of 8 nm are in uniform shapes and narrow size distribution, and the colloid remains stable for more than one month, which makes it convenient for use in practice. The presence of capping agent plays an extra role over nanoparticles stabilization and morphology. The presence of capping agent on the surface of Ag nanoparticle is confirmed by the X-ray photoelectron spectroscopy. It is found that Ag nanoparticles are negatively charged in alkaline condition, whereas they are positively charged in acid condition. Electrosteric effect is responsible for their long-term stability. 相似文献
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分别以柠檬酸钠(CTS)和聚乙烯吡咯烷酮(PVP)为表面修饰剂,采用化学法制备纳米银(分别标记为Ag-CTS和Ag-PVP)。当甲基橙溶液中加入Ag-CTS或Ag-PVP时,S2→S0和S1→S0荧光强度分别明显减弱和增强。不同的是Ag-PVP引起S2→S0和S1→S0荧光强度减弱和增强的幅度更大,且S2→S0荧光峰出现红移。当甲基橙溶液中加入Ag-CTS时,S1→S0荧光强度随时间延长逐渐增强,而加入Ag-PVP时,S1→S0荧光强度则不随时间而变化。颗粒尺寸较大的片状结构纳米银引起S1→S0荧光强度增强比率较小。甲基橙溶液浓度越低,S1→S0荧光强度增强比率越大。研究结果表明,纳米银表面吸附的不同表面修饰剂通过影响纳米银与甲基橙分子间距离进而影响纳米银的荧光增强效应;纳米银尺寸大小则由于所产生的局域面表面等离子共振特点等差异影响其局域场增强效应。 相似文献
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The construction of application-based courses is one of the keys to the development of application-oriented universities. In this paper, the construction of the project-driven "Cosmetics and Spices" course was introduced. Its construction content from the four modules of theory, experiment, open experiment, enterprise project-oriented curriculum design and maker education was explored, and corresponding implementation plans of application-based courses were proposed. 相似文献
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Modification of short-range repulsive interactions in ReaxFF reactive force field for Fe-Ni-Al alloy 下载免费PDF全文
Huaqiang Chen 《中国物理 B》2021,30(8):86110-086110
The short-range repulsive interactions of any force field must be modified to be applicable for high energy atomic collisions because of extremely far from equilibrium state when used in molecular dynamics (MD) simulations. In this work, the short-range repulsive interaction of a reactive force field (ReaxFF), describing Fe-Ni-Al alloy system, is well modified by adding a tabulated function form based on Ziegler-Biersack-Littmark (ZBL) potential. The modified interaction covers three ranges, including short range, smooth range, and primordial range. The short range is totally predominated by ZBL potential. The primordial range means the interactions in this range is the as-is ReaxFF with no changes. The smooth range links the short-range ZBL and primordial-range ReaxFF potentials with a taper function. Both energies and forces are guaranteed to be continuous, and qualified to the consistent requirement in LAMMPS. This modified force field is applicable for simulations of energetic particle bombardments and reproducing point defects' booming and recombination effectively. 相似文献
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以二异辛基磺化琥珀酸钠(CAS No.577-11-7,1,4-二(2-乙基己基)丁二酸酯磺酸钠盐Bis(2-ethylhexyl)sulfosuccinate sodium salt,Dioctyl sulfosuccinate sodium salt,AOT)和柠檬酸钠为表面修饰剂,在60℃及36~50h的水浴条件下采用硼氢化钠还原硝酸银合成出高产率形貌规则的三角形纳米银片。通过控制反应条件可以在边长600~400 nm,厚度5~20 nm范围内调控三角形纳米银片尺寸。通过三角形纳米银片合成过程的显微结构表征提出了三角形框诱导的三角形纳米银片融合生长机制。在AOT表面修饰剂作用下,纳米银粒子自组装融合生长形成三角形纳米框。小的纳米银粒子的融合、消耗促进三角形纳米框形成三角形纳米片。AOT浓度、反应时间和溶液pH值等因素的研究进一步表明了在一定的条件下以三角形框形成为基础的三角形纳米银片的融合生长机制。 相似文献