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1.
石墨质碳质材料因具有良好的电学、力学、热学性能而在电子设备,复合材料,电池,传感器中得到广泛应用,但针对生产能耗高,污染大,成本高,不可控等现状是急需解决的核心问题。因此,通过使用较简单和成本低的制造技术在纳米级器件中获得石墨碳结构的方法是一个有吸引力的探索领域。表面等离激元技术因具有环境友好、能耗低等优点而受到广泛关注,利用等离激元技术诱导大分子链状聚合物石墨化就是一种具有广阔前景的制备技术,而Cu作为贱金属具有产量高,价格便宜等优势。基于表面等离激元技术,利用激光辐射粗糙Cu表面上的聚丙烯腈(PAN)+碳纳米管(CNT),而使聚丙烯腈在金属表面被石墨化。通过改变基底刻蚀时间、退火温度、退火时间、激光强度系统地研究了PAN/Cu和PAN+CNT/Cu得到最佳石墨化条件。实验结果表明:以PAN作为探针分子,在2.5 mol·L-1硝酸刻蚀15min的铜基底上,观察到了增强因子为1.39×104的表面增强拉曼散射(SERS)效应。通过使用拉曼激光作为光源,在退火温度为140 ℃时,可以观察到石墨化的PAN分子结构缺陷较少,碳氮三键消失,其ID/IG可达1.160 8。CNT进一步用于改变粗糙铜基底的光催化性能,我们使用硝酸改性的多臂碳纳米管(MWCNT)与PAN结合对催化系统进行改进,当掺入2%CNT后,通过表面等离激元PAN可以在40 ℃的条件下实现石墨化,其ID/IG达到0.942 1,并且激光的引入大大提高了石墨化位点的可控性,将其归因于激光照射下铜表面产生的热电子对PAN的催化作用,并提出可能存在两种催化和石墨化的机制,一种为热电子通过CNT使PAN石墨化,另一种为热电子通过CNT作用于PAN附近的O2,通过·O-2使PAN石墨化。  相似文献   
2.
蔡金明  杨群 《光谱实验室》2007,24(5):863-867
用傅里叶红外光谱法对彝药大红袍的药物活性与光谱的关系进行研究,通过分析,可知大红袍根皮的收敛止血作用与鞣质的2925.5、1035.2 cm-1等峰有关,顺气止痛与挥发油的1617.7cm-1等峰有关;根心的收敛止血作用与鞣质的2926.0、1048.9 cm-1等峰有关,顺气止痛与挥发油的1617.2、1732.3 cm-1等峰有关,且根皮的药物活性比根心好.这为彝药大红袍的快速鉴定、药理分析和质量监控提供科学依据.  相似文献   
3.
超高真空(ultra-high vacuum,UHV)环境下的表面化学反应是构筑二维(two-dimensional,2D)功能纳米材料的重要方法,近年来,已经引起越来越多研究者的关注.本综述介绍了近几年来有机分子表面化学反应的几种主要类型,如有机金属配位反应、脱卤反应、脱氢环化、缩聚反应、炔烃偶合等,以及利用超高真空扫描隧道显微镜(STM)等测试手段对反应过程以及所形成的精细结构进行分析,特别是反应后结构中分子的连接方式,如有机金属配位键,C-C键,以及氢键等.  相似文献   
4.
A single ZnO nanowire with intrinsic oxygen vacancies is utilized to fabricate four-contact device with focus ion beam lithography technique. Cathodoluminescent spectra indicate strong near-UV and green emission at both room temperature and low temperatures. Experimental measurement shows the temperature-dependent conductivity of the ZnO nanowire at low temperatures (below 100 K). The further theoretical analysis confirms that weak localization plays an important role in the electrical transport, which is attributed to the surface states induced by plenty of oxygen vacancies in ZnO nanowire.  相似文献   
5.
Two kinds of forest-like and desert-like patterns are formed by thermal evaporation of 4-dicyanovinyl-N, Ndimethylamino-1-naphthalene (DDAN) onto SiO2 substrates. Based on thermal kinetics of the molecules on the substrate the transformation between the forest and desert patterns is due to two factors. The first one is the diffusion length, which is related to the deposition rate, the diffusion potential energy barrier and the substrate temperature. The second one is the strong interaction between the two polarity chemical groups of the molecules, which is beneficial to the formation of branches. Totally different patterns are also found on mica substrates, and are attributed to the anisotropic diffusion and the stronger interaction between DDAN molecules and the mica surface.  相似文献   
6.
Topological defects in graphene induce structural and electronic modulations.Knowing exact nature of brokensymmetry states around the individual atomic defects of graphene is very important for understanding the electronic properties of this material.We investigate structural dependence on localized electronic states in the vicinity of topological defects on a highly oriented pyrolytic graphite(HOPG)surface,using scanning tunneling microscopy and spectroscopy.Several inherent topological defects on the HOPG surface and the local density of states surrounding them are explored,visualized as scattering wave-related(√3×√3)R30°superstructures and honeycomb superstructures.In addition,the superstructures observed near the grain boundary have a much higher decay length at specific sites than that reported previously,indicating far greater electron scattering on the quasi-periodic grain boundary.  相似文献   
7.
张辉  熊玮  卢建臣  蔡金明 《化学进展》2022,34(3):557-567
纳米石墨烯在磁学上的优异表现开始获得了更多的关注和研究。由于不饱和电子的存在,磁性纳米石墨烯的湿法化学法合成难度提高,借助超高真空下的表面催化,可以精确地实现将设计好的前驱体分子向磁性纳米石墨烯转变。相较于过渡金属的磁性,纳米石墨烯拥有更高的自旋波刚度、更弱的自旋-轨道耦合作用、更为精细的耦合作用、更长的自旋寿命,使其在自旋电子器件以及基础研究领域拥有很高的研究潜力。由于不饱和电子的存在,提高了湿法化学法合成出磁性纳米石墨烯的难度。近年来,借助超高真空下的表面催化,可以精确地实现将设计好的前驱体分子制备成磁性纳米石墨烯。进一步地,可以利用通过针尖操纵以及将磁性纳米石墨烯进行连接形成二聚体或者磁性链来进行磁性调控和研究。本综述结合近几年超高真空下纳米石墨烯的磁性研究,介绍了纳米石墨磁性的产生和利用超高真空扫描隧道显微技术对其结构和磁性的表征,以及在此基础上对纳米石墨烯磁性的磁序调控。  相似文献   
8.
张辉  蔡晓明  郝振亮  阮子林  卢建臣  蔡金明 《物理学报》2017,66(21):218103-218103
石墨烯由于其独特的晶体结构展现出了特殊的电学特性,其导带与价带相交于第一布里渊区的六个顶点处,形成带隙为零的半金属材料,具有优异的电子传输特性的同时也限制了其在电子学器件中的使用.因而科研人员尝试各种方法来打开其带隙并调控其能带特性,主要有利用缺陷、应力、掺杂、表面吸附、结构调控等手段.其中石墨烯纳米带由于量子边界效应和限制效应,存在带隙.本综述主要介绍了制备各类石墨烯纳米带的方法,并通过精确调控其细微结构,从而对其进行精确的能带调控,改变其电学特性,为其在电子学器件中的应用提供一些可行的方向.  相似文献   
9.
路红亮  张晨栋  蔡金明  高敏  邹强  郭海明  高鸿钧 《中国物理 B》2011,20(10):107301-107301
A method of measuring the thermoelectric power of nano-heterostructures based on four-probe scanning tunneling microscopy is presented. The process is composed of the it in-situ fabrication of a tungsten-indium tip, the precise control of the tip-sample contact and the identification of thermoelectric potential. When the temperature of the substrate is elevated, while that of the tip is kept at room temperature, a thermoelectric potential occurs and can be detected by a current-voltage measurement. As an example of its application, the method is demonstrated to be effective to measure the thermoelectric power in several systems. A Seebeck coefficient of tens of μV/K is obtained in graphene epitaxially grown on Ru (0001) substrate and the thermoelectric potential polarity of this system is found to be the reverse of that of bare Ru (0001) substrate.  相似文献   
10.
We investigate the thermoelectric-transport properties of metal/graphene/metal hetero-structure.We use a single band tight-binding model to present the two-dimensional electronic band structure of graphene.Using the Landauer-Butticker formula and taking the coupling between graphene and the two electrodes into account,we can calculate the thermoelectric potential and current versus temperature.It is found that in spite of metal electrodes,the carrier type of graphene determines the electron motion direction driven by the difference in temperature between the two electrodes,while for n type graphene,the electrons move along the thermal gradient,and for p type graphene,the electrons move against the thermal gradient.  相似文献   
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