Carbon nanotubes contacts

FIGURE 15.21 Atomic force microscope (AFM) image of a carbon nanotube contacted by two metal electrodes and Raman spectra taken from the nanotube. (Reprinted from web http //www-rcf.usc. edu/ scronin with permission from Dr S.B. Cronin.)... 

Bruque NA, Ashraf MK, Beran GJO et al (2009) Conductance of a conjugated molecule with carbon nanotube contacts. Phys Rev B Condens Matter Mater Phys 80 155455/1-155455/13... 

Figure 26.3 An atomic force microscope (AFM) amplitude image of a field-effect transistor comprising of a single semiconducting carbon nanotube contacted with electrodes separated by 1.5 pm.

T. Werder, J. H. Walther, and P. Koumoutsakos, Hydrodynamics of Carbon Nanotubes-Contact Angle and Hydrophobic Hydration. Computational Nanoscience and Nanotechnology. Weinbergstrasse, Zurich Institute of Computational Science (2002]. 

Early transport measurements on individual multi-wall nanotubes [187] were carried out on nanotubes with too large an outer diameter to be sensitive to ID quantum effects. Furthermore, contributions from the inner constituent shells which may not make electrical contact with the current source complicate the interpretation of the transport results, and in some cases the measurements were not made at low enough temperatures to be sensitive to 1D effects. Early transport measurements on multiple ropes (arrays) of single-wall armchair carbon nanotubes [188], addressed general issues such as the temperature dependence of the resistivity of nanotube bundles, each containing many single-wall nanotubes with a distribution of diameters d/ and chiral angles 6. Their results confirmed the theoretical prediction that many of the individual nanotubes are metallic. 

Song et al. [16] reported results relative to a four-point resistivity measurement on a large bundle of carbon nanotubes (60 um diameter and 350 tm in length between the two potential contacts). They explained their resistivity, magnetoresistance, and Hall effect results in terms of a conductor that could be modeled as a semimetal. Figures 4 (a) and (b) show the magnetic field dependence they observed on the high- and low-temperature MR, respectively. 

These problems have been improved in recent years by the microfabrication of sharp tips with radii less than 10 nm, the observation in an SEM or STEM of the exact radius before and after the experiment, the use of robust carbon-nanotube probes, and general improvements in control electronics. However, another method used initially was the attachment of a small colloid particle in place of the AFM tip. These particles were considered a reasonably good approximation to a single-asperity contact their radii were accurately known and remained the same for the duration of the experiment. Such probes have also been used to investigate colloids where surface roughness is an important aspect of the colloid interaction. 

Figure 17.4 Cartoon representation of strategies for studying and exploiting enzymes on electrodes that have been used in electrocatalysis for fuel cells, (a) Attachment or physisorption of an enzyme on an electrode such that redox centers in the protein are in direct electronic contact with the surface, (b) Specific attachment of an enzyme to an electrode modified with a substrate, cofactor, or analog that contacts the protein close to a redox center. Examples include attachment of the modifier via a conductive linker, (c) Entrapment of an enzyme within a polymer containing redox mediator molecules that transfer electrons to/from centers in the protein, (d) Attachment of an enzyme onto carbon nanotubes prepared on an electrode, giving a large surface area conducting network with direct electron transfer to each enzyme molecule.

An additional and very attractive aspect of molecular qubits is the fact that they are stable in solution, and that the ligand shell can be functionalized with specific chemical groups. In recent years, this has enabled depositing molecular clusters onto different substrates and grafting them to nanostructures or devices, such as carbon nanotube single electron transistors or point contacts [112]. These devices... 

Direct consumption sugar, 23 450-451 Direct contact heat exchangers, 13 268 Direct cooler evaporators, 21 537 Direct-coupled plasma (DCF), 25 370 Direct covalent carbon nanotube functionalization, 17 54-55 Direct current (dc) diode sputtering, 24 730-731. See also dc sensing current... 

Concerns regarding the toxicity and environmental effects of polymer-based nanocomposites, such as those derived from clay nanoparticles or carbon nanotubes, throughout their life cycle, from formulation, polymerisation, compounding, fabrication, use, disposal and degradation, are described. The potential of nanoparticles to enter the body by skin contact or inhalation is discussed. Accession no.927669... 

The conductive properties of SWCNTs were predicted to depend on the helicity and the diameter of the nanotube [112, 145]. Nanotubes can behave either as metals or semiconductors depending upon how the tube is rolled up. The armchair nanotubes are metallic whereas the rest of them are semiconductive. The conductance through carbon nanotube junctions is highly dependent on the CNT/metal contact [146]. The first measurement of conductance on CNTs was made on a metallic nanotube connected between two Pt electrodes on top of a Si/Si02 substrate and it was observed that individual metallic SWCNTs behave as quantum wires [147]. A third electrode placed nearby was used as a gate electrode, but the conductance had a minor dependence on the gate voltage for metallic nanotubes at room temperature. The conductance of metallic nanotubes surpasses the best known metals because the... 

Perello DJ, Chulim S, Chae SJ et al (2010) Anomalous Schottky barriers and contact band-to-band tunneling in carbon nanotube transistors. ACS Nano 4 3103-3108... 

Shen X, Sun L, Benassi E et al (2010) Spin filter effect of manganese phthalocyanine contacted with single-walled carbon nanotube electrodes. J Chem Phys 132 054703/ 1-054703/6... 

Javey A, Tu R, Farmer DB et al (2005) High performance n-type carbon nanotube field-effect transistors with chemically doped contacts. Nano Lett 5 345-348... 

Ding L, Wang S, Zhang Z et al (2009) Y-contacted high-performance n-type single-walled carbon nanotube field-effect transistors scaling and comparison with Sc-contacted devices. Nano Lett 9 4209-4214... 

Methods to electrically wire redox proteins with electrodes by the reconstitution of apo-proteins on relay-cofactor units were discussed. Similarly, the application of conductive nanoelements, such as metallic nanoparticles or carbon nanotubes, provided an effective means to communicate the redox centers of proteins with electrodes, and to electrically activate their biocatalytic functions. These fundamental paradigms for the electrical contact of redox enzymes with electrodes were used to develop amperometric sensors and biofuel cells as bioelectronic devices. 

Wang, X.T., Padture, N.P., Tanaka, H. et al., Contact-damage-resistant ceramic/ single-wall carbon nanotubes and ceramic/graphite composites, Nature Mater., 2004, 3(8) 539. 

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