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纳米粒子的自组装和有序组装膜的结构与性质近年来受到了人们的广泛关注,纳米粒子的表面结构与性质对由其组装成的有序膜的结构与性质有直接的影响。文章报道了利用自组装技术制备的银纳米粒子与双亲有机分子的单层和多层复合LB膜,通过吸收光谱和表面增强拉曼光谱研究了银纳米粒子与吸附分子间的相互作用,探讨了复合膜的成膜特性及银纳米粒子的拉曼增强特性。十八胺/银粒子复合LB膜的吸收光谱及拉曼光谱显示,十八胺分子与银纳米粒子表面的活位通过NH2中的氮原子以复合体的形式结合;同时,在激发光的作用下复合体可能存在光催化过程。根据银粒子复合LB膜的实验结果,十八胺和十八酸之间的反应产物在复合膜中起空间位阻作用,与银粒子表面的相互作用较弱。 相似文献
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金银纳米粒子的电化学性质及联苯胺的SERS研究 总被引:4,自引:0,他引:4
采用柠檬酸钠还原氯金酸,硼氢化钠还原硝酸银分别制备了较小粒径的金、银纳米粒子.运用紫外可见吸收光谱(UV-Vis)、扫描电子显微镜(SEM)、循环伏安法(CV)对金、银纳米粒子进行了表征.结果表明:所得金、银纳米粒子粒径分别约为16和10 nm,并能以亚单层形式组装于导电玻璃(ITO)表面;CV图显示金、银纳米粒子分别有一对不对称的氧化还原峰,而且纳米粒子的浓度对其氧化还原电位存在一定的影响.采用自组装方法,以联苯胺为偶联分子,在粗糙金基底表面构筑了金/银纳米粒子的双层有序结构.表面增强拉曼光谱研究表明,在有序金银纳米粒子组装体中偶联分子的拉曼散射得到了增强. 相似文献
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报道了一种单分散“核-卫星”纳米金簇状结构的构造方法,不但可以有效调节卫星粒子的数目,还能实现核与卫星粒子间距离的准确控制. 利用DNA分子高度可控的程序化自组装性能,通过合理控制组装过程中核与卫星粒子表面的DNA修饰密度以及不同金纳米粒子的化学计量比,实现了单分散核-卫星结构的高产率组装,结合使用凝胶电泳这一高效的纳米分离技术实现了目标产物的分离. 该方法保证了卫星粒子表面极低的DNA覆盖率,使其与蛋白分子中的巯基基团具有较强的化学亲和作用,使得金纳米粒子在蛋白功能化石墨烯表面的二维层次化自组装得以实现. 相似文献
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在4,4’-二硫联吡啶在Au表面形成自组装单分子层膜的基础上,采用表面增强拉曼散射光谱(SERS)研究了在不同pH值条件下金纳米粒子在4,4’-二硫联吡啶自组装单分子膜/Au体系表面的组装。研究结果表明,由于处于单分子膜表面的吡啶环中氮原子的质子化程度随溶液环境中pH值的变化而变化,使得金纳米粒子与单分子膜表面间的结合作用程度不同,由此会引起金纳米粒子在单分子膜表面的覆盖度存在差异,并最终导致所观测到的4-巯基吡啶自组装单分子膜的SERS光谱强度存在明显的差异。而且,令人感兴趣的是,所观测到的SERS谱峰强度随金纳米粒子组装时pH值的变化呈现出明显的规律性。结合分子结构特征的分析,初步阐明了SERS谱峰强度随pH值这一组装条件的改变而发生规律性变化的内在原因。 相似文献
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采用水相硅烷化方法,将γ-氨基丙基三乙氧基硅烷[H2N(CH2)3Si(OC2H5)3](APES)组装在石英表面,在基底表面修饰上氨基为末端的单层膜,并进一步在这种功能化的单层膜基底上组装金纳米粒子得到金纳米粒子/APES/石英的纳米复合结构.以制备的金纳米粒子自组装膜修饰石英为基底及DL-半胱胺酸为中介,利用桑色素(Morin)和DL-半胱胺酸的化学吸附作用,将桑色素间接组装在金纳米粒子自组装膜修饰石英基底表面,所构建的桑色素修饰金纳米粒子自组装膜对三苯基锡有灵敏的荧光识别作用.文章着重研究了桑色素修饰金纳米粒子自组装膜的制备以及组装条件对其荧光行为的影响,探讨了膜的响应特性及响应机理. 相似文献
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Metal–insulator–metal (MIM) devices play an important role in information storage cells. In this research, a MIM with an insulator made from polydimethylsiloxane blended with gold nanoparticles has been investigated. The current–voltage characteristic demonstrates a negative differential resistance (NDR) and memory effect. This article attempts to explain the NDR and memory effect, using the charge trapping and releasing mechanisms of the gold nanoparticles and also electron tunneling mechanisms. 相似文献
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The role of organic capping ligand of semiconductor nanoparticles in dictating the interfacial charge transfer processes in hybrid semiconductor nanoparticles/polymer-based photovoltaic devices is investigated. Morphology, optical and structural study of the CdS nanoparticles and the hybrid material were accomplished using X-ray diffraction (XRD), absorption (UV–vis), atomic force microscopy (AFM), transmission electron microscopy (TEM), photoluminescence (PL) and time resolved photoluminescence spectroscopy (PLRT). A broad band absorption in UV–visible region and considerable fluorescence quenching of MEH-PPV in the composites are noted indicating a photo-induced charge transfer and dissociation of excitons. Time-resolved photoluminescence measurements indicating decreased lifetime further confirm this process. The solar cells open-circuit voltage and short-circuit current were improved using thiophenol modified CdS nanoparticles as electron acceptor in comparison to MEH-PPV only device demonstrating a promising approach to enhance charge transport in the hybrid nanoparticles–polymer composite photovoltaic cells (PV). 相似文献
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We investigated single electron tunneling (SET) behavior of dodecanethiol-coated Au nanoparticles of two different sizes (average sizes are 5 nm and 2 nm) using nanogap electrodes, which have a well-defined gap size, at various temperatures. The Coulomb staircases and the Coulomb gap near-zero bias voltage caused by the suppression of the tunneling electrons due to the Coulomb blockade effect were observed in the current-voltage (I-V) curves of both sizes of nanoparticles at a low temperature (10 K). At room temperature, the Coulomb gap was observed only in the I-V curve of the smaller nanoparticles. This result indicates that the charging energy of the smaller nanoparticles is enough to overcome the thermal energy at room temperature. This suggests that it is possible to operate the SET devices at room temperature using the smaller nanoparticles as a Coulomb island. 相似文献
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The stability of the current across Si nanochain network is investigated using a micromanipulator in a scanning electron microscope system. We confirm that the current is dominated by the tunneling of electrons between Si nanoparticles. We observe large current fluctuations at a high bias voltage, while the current is stable at a relatively low bias voltage. The origin of the fluctuation is discussed in terms of percolation. 相似文献
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搭建了电爆炸金属丝实验平台,在空气中电爆炸铁丝来制备纳米金属颗粒。利用电阻分压器与Rogowski线圈来测量电爆炸过程中铁丝上的负载电压与电流。将负载电压与电流之积进行时间积分来估算沉积在铁丝上的能量。使用光电探测器对电爆炸过程中产生的等离子体发光信号进行探测。对铁丝电爆炸后形成的产物使用高倍显微镜、扫描电镜(SEM)、透射电镜(TEM)、能谱分析仪(EDS)以及X射线衍射仪(XRD)进行观测,来研究其物相特性。实验结果表明:电爆炸过程中,当铁丝由液相变为气相时,其电阻急剧增加,因此电流几乎不能流过铁丝,同时铁丝上的负载电压会趋近于电容器的初始充电电压。随着能量的持续积累,等离子体在爆炸腔中形成。由于原本被阻断的电流能够从低电阻等离子体中流过,因此电压电流波形变为欠阻尼波形。电爆炸铁丝所得的产物为Fe3O4纳米颗粒,其中大部分呈规则的球形。Fe3O4纳米颗粒的粒径主要分布在30~60 nm之间,并且符合对数正态分布。 相似文献
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R. Russo C. Granata P. Walke A. Vettoliere E. Esposito M. Russo 《Journal of nanoparticle research》2011,13(11):5661-5668
Integrated magnetic sensors based on niobium dc SQUID (Superconducting Quantum Interference Device) for nanoparticle characterizations
are presented. The SQUIDs consists of two Dayem bridges of 90 nm × 250 nm and loop area of 4, 1, and 0.55 μm2. The devices are realized by using an e-beam lithography nano-fabrication process which can directly pattern the devices
in an electron-positive resist and then transferred to a 20 nm single niobium layer by a lift-off post-process. The SQUIDs
were designed to have a hysteretic current–voltage characteristic in order to work as a magnetic flux-current transducer.
The presence of an integrated niobium coil, tightly coupled to the SQUID, allows us to easily excite the SQUID and to flux
bias the SQUID at its optimal working point. Current–voltage characteristics, critical current as a function of the external
magnetic field and switching current distributions were performed at liquid helium temperature. A critical current modulation
of about 20% and a current-magnetic flux transfer coefficient (responsivity) of 30 μA/Φ0 have been obtained, resulting in a magnetic flux resolution better than 1 mΦ0. The authors performed preliminary measurements with and without iron oxide nanoparticles on the SQUID loop in order to show
the device sensitivity in view of nano-magnetism applications. It was showed that the presence of magnetic nanoparticles can
be easily detected and the magnetic relaxation curve measured. 相似文献
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Kyeongchan Noh Minsu Kim Sang-Hyun Lee Hwang-Sik Yun Tae-Hyeon Lim Yeongho Choi Ki-Ju Kim Yiran Jiang Keonwon Beom Minju Kim Young-Gwang Kim Pilwoo Lee Nuri Oh Bong Hoon Kim Chansun Shin Hyun Ho Lee Tae-Sik Yoon Moonsub Shim Seong-Yong Cho 《Current Applied Physics》2019,19(9):998-1005
The aging of ZnO nanoparticles in quantum dot light-emitting diode (QD-LED) structures was studied. Coarsening of as-synthesized ZnO nanoparticles is observed in both solution and thin film structures, which potentially deteriorates the performance of QD-LED devices over time. First, the temperature effect on ZnO coarsening was investigated, and it was revealed that aging of ZnO nanoparticles is faster at higher temperature due to a diffusion-controlled mechanism of nanoparticle coarsening. To observe aggregation of ZnO in the film state, the electron transporting part (ZnO/Al) of the QD-LED structure was prepared. The current density of a ZnO film and an electron-only device (QD/ZnO between two electrodes) was also measured. Resistance of the film increased as a function of aging time, which corresponded with observations of the ZnO film by optical microscopy. Aggregation of ZnO nanoparticles was directly measured by the root-mean-square value using atomic force microscopy. Ethanolamine (EA) stabilizer was added to the ZnO solution to disperse the ZnO nanoparticles without aggregation. The effect of EA on the surface passivation of the ZnO found to suppress pinhole formation, as revealed by scanning electron microscopy observations. Finally, the device lifetime was measured for QD-LEDs with EA-stabilized ZnO to understand the effect of ZnO aging on long-term QD-LED device operation. 相似文献
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Ch. Sargentis K. Giannakopoulos A. Travlos D. Tsamakis 《Physica E: Low-dimensional Systems and Nanostructures》2007,38(1-2):85
Floating gate devices with nanoparticles embedded in dielectrics have recently attracted much attention due to the fact that these devices operate as non-volatile memories with high speed, high density and low power consumption. In this paper, memory devices containing gold (Au) nanoparticles have been fabricated using e-gun evaporation. The Au nanoparticles are deposited on a very thin SiO2 layer and are then fully covered by a HfO2 layer. The HfO2 is a high-k dielectric and gives good scalability to the fabricated devices. We studied the effect of the deposition parameters to the size and the shape of the Au nanoparticles using capacitance–voltage and conductance–voltage measurements, we demonstrated that the fabricated device can indeed operate as a low-voltage memory device. 相似文献
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初步分析了AlGaN/GaN 器件上的kink效应. 在直流模型的基础上, 建立了AlGaN/GaN 高电子迁移率晶体管中kink效应的半经验模型, 并加入了kink效应发生的漏源偏压与栅源偏压的关系. 该模型得出较为准确的模拟结果, 可用来判断kink效应的发生和电流的变化量. 最后, 我们采用模型仿真结合实验分析的方法, 对kink效应进行了一定的物理研究, 结果表明碰撞电离对kink效应的发生有一定的促进作用. 相似文献