1. Tae-Youl Choi, Dimos Poulikakos, Joy Tharian, and Urs Sennhauser. (2006). Measurement of the thermal conductivity of individual carbon nanotubes by the four-point three-ω method. NanoLetters, Vol. 6, No. 8 pp1589-1593
www.ltnt.ethz.ch
Abstract: The thermal conductivity of individual multiwalled carbon nanotubes was measured by utilizing the four-point-probe third-harmonic method, based on the fact that the third harmonic amplitude and phase as a response to applied alternate current at fundamental frequency, ω, can be expressed in terms of thermal conductivity and diffusivity. To this end, a microfabricated device composed of four metal electrodes was modified to manufacture nanometer-sized wires by using a focused ion beam source. A carbon nanotube could then be suspended over a deep trench milled by the focused ion beam, preventing heat loss to the substrate. Compared with the two-point-probe technique, a significant improvement in accuracy is assured by using four probes, because the contact contribution to the determination of the thermal conductivity is eliminated, making it possible to measure the correct signals of first and third harmonics. The multiwalled carbon nanotube was modeled as a one-dimensional diffusive energy transporter and its thermal conductivity was measured at room temperature under vacuum to be 300 ± 20 W/mK.
2. S. Nuriel, L. Liu, A.H. Barber and H.D. Wagner. (2005, March). Direct measurement of multiwall nanotube surface tension. Chemical physics letters,
Volume 404, Issues 4-6, Pages 263-266
Abstract: The contact angle between multiwall carbon nanotubes, carbon nanofiber and carbon fibers, and polypropylene and polyethylene glycol was measured using electron microscopy. Good wetting was observed using both polymers. The Owens–Wendt plotting procedure was used to obtain the polar, dispersive and total surface energy parameters for the three types of carbon materials. Minor differences only were found between these.
3. Y. Wang, K. Kempa, B. Kimball, J. B. Carlson,G. Benham,W. Z. Li, T. Kempa, J. Rybczynski, A. Herczynski, and Z. F. Ren. (2004, September). Receiving and transmitting light-like radio waves: Antenna effect in arrays of aligned carbon nanotubes. Applied physics letters, Vol 85, 13.
www.physics.bc.edu
Abstract: We present optical measurements of random arrays of aligned carbon nanotubes, and show that the response is consistent with conventional radio antenna theory. We first demonstrate the polarization effect, the suppression of the reflected signal when the electric field of the incoming radiation is polarized perpendicular to the nanotube axis. Next, we observe the interference colors of the reflected light from an array, and show that they result from the length matching antenna effect. This antenna effect could be used in a variety of optoelectronic devices, including THz and IR detectors.
4. H. Busta, Z. Tolt,J. Montgomery and A. Feinerman. (2005,March). Field emission
from teepee-shaped carbon nanotube bundles. J. Vac. Sci. Technol., B Volume 23, Issue 2, pp. 676-679
Abstract: Randomly, but perpendicular to the surface, oriented carbon nanotubes of about 5 µm in height and submicrometer spacing were coated with 3.5 µm plasma enhanced CVD silicon dioxide. Subsequent removal of the oxide in buffered HF, followed by de-ionized water rinse and nitrogen blow drying resulted in the formation of a peculiar pattern of nanotubes similar in shape to teepees or the hair cells of the inner ear. Since several nanotubes can supply current to the apexes of these bundles and since the spacing between the apexes is increased, thus reducing the electrostatic screening effect, these structures might have interesting field emission properties. Field emission measurements were performed at pressures of about 1×10–8 Torr. Room temperature emission was poor with turn-on fields of about 30 V/µm due to surface contamination effects. Turn-on fields of about 15 V/µm and macroscopic current densities of 50 mA/cm2 were obtained when the measurements were performed at 170 °C.
5. Billy Smith†, Kevin Wepasnick, Kaitlin E. Schrote, Hyun-Hee Cho, William P. Ball and D. Howard Fairbrother. (2009,July 7). Influence of surface oxides on the colloidal stability of multi-walled carbon nanotubes: a structure−property relationship. Langmuir, Volume 25, Issue 17, pp.
9767-9776
Abstract: As with all nanomaterials, a large fraction of the atoms in carbon nanotubes (CNTs) reside at or near the surface. Consequently, surface chemistry will play a crucial role in determining the fate and transport of CNTs in aquatic environments. Frequently, oxygen-containing functional groups (surface oxides) are deliberately grafted into the CNT surface to promote colloidal stability. To study the influence that both the oxygen concentration and the oxygen functional-group distribution have on the colloidal stability of multiwalled carbon nanotubes (MWCNTs), a suite of oxidized MWCNTs (O-MWCNTs) were created using different oxidizing agents and reaction conditions. Stable colloidal suspensions were prepared by low-power sonication of O-MWCNT powders in Milli-Q water. Results from TEM, AFM, DLS, and XPS measurements revealed that, irrespective of the surface chemistry, the colloidal suspensions were composed of individual nanotubes with comparable length distributions. The critical coagulation concentrations (CCC) of O-MWCNTs that exhibited different surface chemistries were measured with time-resolved dynamic light scattering (TR-DLS)using NaCl as the electrolyte. Over a range of environmentally relevant pH values, linear correlations were found to exist between the CCC, total oxygen concentration, and surface charge of O-MWCNTs. In contrast to surface charge, electrophoretic mobility did not prove to be a useful metric of colloidal stability.
Information obtained from chemical derivatization studies, carried out in conjunction with XPS, revealed that the distribution of oxygen-containing functional groups also influences the colloidal stability of O-MWCNTs, with carboxylic acid groups playing the most important role. This study highlights the fact that quantitative relationships can be developed to rationalize the influence of surface chemistry on the behavior of
nanomaterials in aquatic environments.
6. Pengfei Wu, B. Kimball, J. Carlson and D.V.G. L. N. Rao(2004 July 2) Light Scattering of Periodic ß-Aligned Carbon Nanotubes PHYSICAL REVIEW LETTERS Volume 93, Number 1, pp. 013902-1 -- 013902-4
http://prl.aps.org/abstract/PRL/v93/i1/e013902
Abstract: We report interesting results of light scattering in periodic ß-aligned carbon nanotubes (CNTs).
Observations of spatial symmetric scattering as a consequence of strong interference agree well with analysis of periodic hexagonal lattices of the CNTs.We found that the scattering is maximally enhanced at a particular angle where the backward incident and scattered directions are exactly superposed for both s and p polarization. The experimental results are explained using a mechanism of electromagnetically
induced excitation of surface plasmon polaritons which result in enhanced backscattering
effect in CNTs.
|
