场离子显微镜观测单壁碳纳米管

场离子显微镜是具有原子级分辨能力的尖端表面分析工具。它适用于纳米尺度的单壁碳纳米管（SWCNTs）末端表面原子排列的观测。利用范氏力将SWCNTs组装到钨针尖上,用场离子显微镜观察了这种针尖样品。在观察过程中对针尖样品进行了加热处理,既除掉非晶的C原子,也破坏了由于碳纳米管切割制造过程使用表面活化剂引起的高电阻层,得到了开口SWCNTs的场离子显微镜像,由此推断出SWCNTs束的顶端原子结构,估算出观察到的SWCNTs的直径,并且模拟了其中一个图像所代表的SWCNTs顶端开口的原子排列,推断出产生这个图像的SWCNTs是（7,7）型结构。     

利用场发射显微镜研究单壁碳纳米管的场发射特性

利用场发射显微镜研究了单壁碳纳米管(SWCNTs)的场发射特性.由于实验中所用的SWCNTs的长度基本一致,因此能同时观察到多根SWCNTs的场发射像.SWCNTs的场发射像随着热处理温度的升高而变化,直至热处理温度过高而塌缩.在一定的实验条件下,观察到了具有精细结构的单根碳纳米管顶端"帽子"的场发射像.电流-电压(I-U)曲线分析表明,SWCNTs的电流来源于场发射.     

用FEM/FIM研究单壁碳纳米管束

利用范氏力将单壁碳纳米管样品组装到钨针尖上 ,用FEM/FIM对同一碳纳米管样品用热处理方法和场脱附方法进行了研究。场离子显微镜是具有原子级分辨能力的尖端表面分析工具 ,由场离子像推测这次组装的样品是由三根单壁碳纳米管突起组成的碳纳米管束。清洁碳纳米管束样品的场发射像和场离子像有极好的对应关系。场脱附后的碳纳米管束的场发射特性较好地符合Fowler Nordheim场发射模型。通过比较碳纳米管束吸附态和热处理后以及场脱附后的Fowler Nordheim曲线的斜率变化 ,得出碳纳米管束样品逸出功的变化 ,再结合场发射像的变化推断出场脱附与热处理结合是一种较理想的获得清洁碳纳米管表面的方法     

用FEM／FIM研究单壁碳纳米管束

利用范氏力将单壁碳纳米管样品组装到钨针尖上，用FEM/FIM对同一碳纳米管样品用热处理方法和场脱附方法进行了研究。场离子显微镜是具有原子级分辨能力的尖端表面分析工具，由场离子像推测这次组装的样品是由三根单壁碳纳米管突起组成的碳纳米管束。清洁碳纳米管束样品的场发射像和场离子像有极好的对应关系。场脱附后的碳纳米管束的场发射特性较好地符合Fowler-Nordheim场发射模型。通过比较碳纳米管束吸附态和热处理后以及场脱附后的Fowler-Nordheim曲线的斜率变化，得出碳纳米管束样品逸出功的变化，再结合场发射像的变化推断出场脱附与热处理结合是一种较理想的获得清洁碳纳米管表面的方法。     

利用场发射显微镜研究单壁碳纳米管的场发射特性

利用场发射显微镜研究了单壁碳纳米管（SWCNTs)的场发射特性。由于实验中所用的SWCNTs的长度基本一致，因此能同时观察到多根SWCNTs的场发射像。SWCNTs的场发射像随着热处理温度的升高而变化，直至热处理温度过高而塌缩。在一定的实验条件下，观察到了具有精细结构的单根碳纳米管顶端“帽子”的场发射像。电流－电压（I－U）曲线分析表明，SWCNTs的电流来源于场发射。     

原子探针场离子显微镜及其应用

<正> 近十年来许多表面分析技术,诸如俄歇电子能谱、X射线光电子能谱、紫外光电子能谱、低能电子衍射等,得到迅速发展。尽管如此,五十年代由Muller发展起来的场离子显微镜仍然是以原子分辨率直接观察固体表面为最基本的工具之一,它能清晰地显示试样表层的原子排列和缺陷,六十年代出现原子探针以后,它与场离子显微镜结合,从此不仅能直接观察表面原子,而且能确定这些原子的化学类别,并对原子过程作出定量研究。场离子显微术的     

用扫描隧道显微镜对材料进行表面修饰的研究

扫描隧道显微镜(STM)是对材料表面进行表面修饰(surface modification)和表面原子操纵(atomcraft)的重要工具。为了了解其机理,选择了场蒸发阈值从大到小有代表性的钨、铂、金、铜做针尖,扫描过程中在针尖与石墨表面之间施加针尖为正的脉冲电压,获得了一些新现象,并对实验结果作了比较,从而在一定程度上确定了脉冲制STM表面修饰实验中针尖与样品之间电场的重要作用。     

基于溶液法的单壁碳纳米管水平取向排列研究进展

单壁碳纳米管(SWCNTs)以其优异的物理、化学及电学性质,在微纳米电子器件领域表现出巨大的应用前景。作为典型的一维纳米材料,SWCNTs呈现出随结构变化的不同导电属性和手性的多样性。然而,通常直接生长制备的SWCNTs是金属性和半导体性碳纳米管的混合物或不同手性结构的混合体,这在很大程度上限制了SWCNTs在电子器件领域中的实际应用。因此,首先需要精细分离出单一导电属性或单一手性的SWCNTs,以满足制作高性能碳纳米管器件的要求。此外,SWCNTs的一维特性使其在性能上显示出极其显著的各向异性,即大部分情况下其轴向性能要优于径向性能。因而,对于SWCNTs的进一步应用来说,其取向排列问题也显得尤为重要。基于上述两个方面的因素,近年来,直接生长后经分散分离处理的SWCNTs通过外界作用力实现其取向排布的方法(即基于溶液法的后排列的方法),引起了研究者们的极大关注。基于溶液法的SWCNTs取向排列方法,需要首先通过表面活性剂或小芳香分子、大环共轭物、核酸、多肽等生物分子的物理吸附或化学修饰来实现SWCNTs的分散及分离,然后结合各种物理、化学方法实现其水平取向排列。随着学者们研究的不断深入,迄今已报道了一些能够实现SWCNTs水平取向排列的简单易行的方法,包括剪切力诱导法、溶剂蒸发自组装法、Langmuir-Blodgett和Langmuir-Schaefer法、化学自组装法、真空过滤法、电磁场诱导法和模板法以及上述两种或几种方法的组合等。但是以上方法在大多数情况下依然存在比较严重的缺陷,如取向过程受分散体系的影响严重,分散及分离过程中会引入表面活性剂、聚合物分散剂等外来杂质并对后续器件制作造成不良影响,以及取向排列面积小、取向效果不理想等。因此,高性能碳纳米管器件的应用不仅需要取向碳纳米管的直径均匀、手性单一,而且需要高度取向、大面积以及取向密度均匀可控,这些仍是亟待解决的巨大的挑战。本文从不同分散体系中SWCNTs的水平取向排列原理出发,在对当前碳纳米管水平取向方法进行了分类的基础上,阐述了各种方法的研究进展现状,比较了其优缺点,并对其今后的研究与发展方向做出了展望。     

单壁碳纳米管-聚合物复合导电薄膜的制备

基于聚合物乳液法,将单壁碳纳米管(SWCNTs)在阿拉伯树胶溶液中经过超声波振荡剥离后,与聚合物乳液直接混合,然后在室温下成膜,制备出了电渗流阈值为0.03%的SWCNTs-苯丙乳液复合导电薄膜,研究了SWCNTs在聚合物中形成导电网络的过程.TEM观察表明:在超声波和阿拉伯树胶溶液的共同作用下,单壁碳纳米管首先由束状被剥离成单根;进一步作用后其表面被缠绕包覆了一层阿拉伯树胶分子;添加其到聚合物乳液中,当添加量达到渗流阈值时,在聚合物乳液的成膜过程中SWCNTs会互相连接形成导电网络.     

场离子显微镜(FIM)及其应用

本文着重介绍场离子显微镜(Field Ion Microscope)的分辨率、放大倍数、离子像的强度、沟道板像增强器、场离子像的形成以及场离子显微镜(FIM)和原子探针场离子显微镜(APFIM)的简单结构与原理。同时还介绍了FIM在固体表面研究中的应用。     

Polydiacetylene single-walled carbon nanotubes nano-hybrid for cellular imaging applications

The functionalization of single-walled carbon nanotubes (SWCNTs) by forming self-assembled supramolecular structure of 10,12-pentacosadiynoic acid (PCDA) on the carbon nanotube wall is reported. PCDA assemblies on SWCNTs (PCDA/SWCNTs) were polymerized by UV irradiation to extensively conjugated polydiacetylene (PDA). PDA/SWCNT was identified by absorption and emission spectroscopy, scanning and transmission electron microscopies (SEM and TEM) and atomic force microscopy (AFM). PDA/SCWNTs showed strong near-infrared (NIR) fluorescence caused by fluorescence resonance energy transfer (FRET) between PDA network and semiconducting SWCNT core. The micro-patterning of biotinylated PDA/SWCNT with FITC-avidin on biotinylated glass surface demonstrated the potential application for a bio-sensing device. Furthermore, the biocompatibility for mammalian cancer cells was tested by viability experiments, which revealed that the PDA/SWCNTs had very low toxicity below 31.3 mg/L in terms of pristine SWCNTs concentration. Also, PDA/SWCNTs inside the cells can be observed by NIR microscopy. This unique modular method of preparation can contribute to diverse functionalities for practical applications in various non-invasive cellular imaging.     

Diameters of single-walled carbon nanotubes (SWCNTs) and related nanochemistry and nanobiology

We reviewed and examined recent progresses related to the nanochemistry and nanobiology of signal-walled carbon nanotubes (SWCNTs), focusing on the diameters of SWCNTs and how the diameters affect the interactions of SWCNT with protein and DNA, which underlay more complex biological responses. The diameters of SWCNTs are closely related to the electronic structure and surface chemistry of SWCNTs, and subsequently affect the interaction of SWCNTs with membrane, protein, and DNA. The surfaces of SWCNT with smaller diameters are more polar, and these with large diameters are more hydrophobic. The preference of SWCNT to interact with Trp/Phe/Met residues indicates it is possible that SWCNT may interfere with normal protein-protein interactions. SWCNT-DNA interactions often change DNA conformation. Besides the promising future of using SWCNTs as delivering nanomaterial, thermal therapy, and other biological applications, we should thoroughly examine the possible effects of carbon nanotube on interrupting normal protein-protein interaction network and other genetic effects at the cellular level.     

Diameters of single-walled CNTs (SWCNTs) and related nanochemistry and nanobiology

We reviewed and examined recent progresses related to the nanochemistry and nanobiology of signal-walled carbon nanotubes (SWCNTs), focusing on the diameters of SWCNTs and how the diameters affect the interactions of SWCNT with protein and DNA, which underlay more complex biological responses. The diameters of SWCNTs are closely related to the electronic structure and surface chemistry of SWCNTs, and subsequently affect the interaction of SWCNTs with membrane, protein, and DNA. The surfaces of SWCNT with smaller diameters are more polar, and these with large diameters are more hydrophobic. The preference of SWCNT to interact with Trp/Phe/Met residues indicates it is possible that SWCNT may interfere with normal protein-protein interactions. SWCNT-DNA interactions often change DNA conformation. Besides the promising future of using SWCNTs as delivering nanomaterial, thermal therapy, and other biological applications, we should thoroughly examine the possible effects of carbon nanotube on interrupting normal protein-protein interaction network and other genetic effects at the cellular level.     

Preparation and investigation on properties of lysozyme chemically bonded to single-walled carbon nanotubes

The purpose of this research is the preparation of a lysozyme-single-walled carbon nanotube (SWCNT) conjugate and investigation of the effect of conjugation on the structure and function of lysozyme. At first, SWCNTs were functionalised by oxygen and lysozyme was coupled to the SWCNTs by carbodiimide method. The high chemical stability of conjugation was purposed for the SWCNTs conjugated enzyme as approved by Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM) images, agarose gel electrophoresis and X-ray diffraction (XRD) patterns. The degree of conjugation was determined by thermogravimetric analysis (TGA) process. The results showed no significant differences between the XRD patterns of the native lysozyme and conjugated lysozyme–SWCNTs and these indicated excellent capacity of the SWCNTs to conjugated enzyme. The gel electrophoresis studies and TEM image confirmed the covalent attachment of the enzyme to the functionalised SWCNTs. These results revealed that the enzyme retain a high fraction of their native structure and activity upon attachment to SWCNTs. Therefore, this conjugated protein represents novel preparations that make it an attractive choice as a natural antimicrobial agent.     

单壁纳米管与对三联苯的交互作用及其束散现象

研究了单壁纳米管(SWCNT)与对三联苯(p-Terphenyl)分子的交互作用和束散现象.SWCNTs分别由电弧放电法和一氧化碳高压分解法(Hipco法)制备.比较了不同制备工艺及纯化处理后SWCNTs与p-Terphenyl交互作用及其束散程度.采用分光和显微镜等技术,探讨了SWCNTs及其与p-Terphenyl交互作用.应用X光能量消散(EDAX)技术,给出了纯化处理前后SWCNTs试样的元素分析.利用萤光分析和原子显微镜技术评估了SWCNTs交互作用及束散程度.研究显示:SWCNTs束散程度及其和p-Terphenyl交互作用的强弱与SWCNTs纯化程度有关.     

Tailored SWCNT functionalization optimized for compatibility with epoxy matrices

We have modified single walled carbon nanotubes (SWCNTs) with well defined matrix-based architectures to improve interface interaction in SWCNT/epoxy composites. The hardener and two pre-synthesized oligomers containing epoxy and hardener moieties were covalently attached to the SWCNT walls by in?situ diazonium or carboxylic coupling reactions. In this way, SWCNTs bearing amine or epoxide-terminated fragments of different molecular weights, which resemble the chemical structure of the cured resin, were synthesized. A combination of characterization techniques such as Raman and infrared absorption (FTIR) spectroscopy, elemental analysis and coupled thermogravimetry-FTIR spectroscopy were used to identify both the functional groups and degree of functionalization of SWCNTs synthesized by the laser ablation and arc-discharge methods. Depending on the type of reaction employed for the chemical functionalization and the molecular weight of the attached fragment, it was possible to control the degree of functionalization and the electronic properties of the functionalized SWCNTs. Improved dispersion of SWCNTs in the epoxy matrix was achieved by direct integration without using solvents, as observed from optical microscopy and rheology measurements of the SWCNT/epoxy mixtures. Composite materials using these fillers are expected to exhibit improved properties while preserving the thermosetting architecture.     

First-principles study of ZnO cluster-decorated carbon nanotubes

We have investigated the structural, electronic and carbon monoxide (CO) detection properties of the ZnO cluster-decorated single-walled carbon nanotubes (SWCNTs) by using density functional theory (DFT). The stable structures of hybrid ZnO/SWCNT materials are that the ZnO cluster plane is perpendicular to the surface of SWCNTs with the Zn atoms towards the SWCNTs (Zn atom above axial C-C bond or above the C atom). For the ZnO cluster-decorated semiconducting SWCNTs, the SWCNTs present p-type characteristics which may lead to the decrease of conductance upon illumination with ultraviolet (UV) light. The CO can be adsorbed on the hybrid ZnO/SWCNT materials due to the charge transfer between them. Compared with isolated ZnO clusters or bare SWCNTs, the ZnO/SWCNT network would have excellent CO detection ability due to their suitable adsorption energy and conductivity.     

Two-Gap Superconductivity in Niobium Carbide-Coated Single-Walled Carbon Nanotubes: A First-Principles Study

Superconductivity in carbon nanotubes is attracting worldwide attention because of the reported high superconducting transition temperature in small-diameter single-walled carbon nanotubes (SWCNTs). However, it is well known that superconductivity in low-dimensional (quasi-1D) systems is not so common due to low density of states (DOS), strong quantum fluctuations and other phenomena in such systems. In this paper, we present theoretical investigations of the proximity effect of superconducting niobium carbide on single-walled carbon nanotube using density functional theory (DFT). The relaxed structure shows that Nb atoms are held around the SWCNT, forming a layer through weak van der Waals’ forces. The stability of the structure has been confirmed by Hirshfeld analysis and Mullikan population analysis as well. The study of the electronic band structure of the pristine and modified SWCNT shows a fascinating condensation of electronic states and a striking shift in the Fermi level. Further, two additional band gaps have appeared below the valence band suggesting some kind of pairing mechanism being operational. This indicates the possibility of superconducting behaviour in SWCNT in proximity of niobium carbide. The relaxed structure thus envisions the feasibility and stability of NbC-coated SWCNTs which will have superconducting properties as well as the remarkable mechanical and optical properties of SWCNTs. This prediction seeks interest of the researchers to try and develop such a novel nanomaterial which, if realized, will prove to be highly significant for many technological applications.     

Synthesis and characterization of polyurethane-grafted single-walled carbon nanotubes via click chemistry

Polyurethane (PU)-grafted carbon nanotubes were synthesized by the coupling of alkyne moiety decorated single walled carbon nanotube (SWCNT) with azide moiety containing PU using Cu(I) catalyzed Huisgen [3 + 2] cycloaddition click chemistry. The azide moiety containing poly(s-caprolactone)diol was synthesized by ring-opening polymerization and further used for PU synthesis. Alkyne-functionalizion of SWCNT was completed by the reaction of p-aminophenyl propargyl ether with SWCNT using a solvent free diazotization procedure. Nuclear magnetic resonance, Fourier transform infrared, and Raman spectroscopic measurements confirmed the functionalization of SWCNT. Scanning electron microscopy and transmission electron microscopy images showed an excellent dispersion of SWCNTs, and specially debundling of SWCNTs could be observed due to polymer assisted dispersion. A quantitative grafting was successfully achieved even at high content of functional groups.