Bulletin of the American Physical Society
2009 APS March Meeting
Volume 54, Number 1
Monday–Friday, March 16–20, 2009; Pittsburgh, Pennsylvania
Session J24: Focus Session: Nanotube Applications |
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Sponsoring Units: DMP Chair: Stefano Curtarolo, Duke University Room: 326 |
Tuesday, March 17, 2009 11:15AM - 11:51AM |
J24.00001: Nanotube and Graphene ElectroMechanics Invited Speaker: Carbon nanotubes and graphene have attracted a lot of attentions as high-frequency mechanical resonators. For instance, nanotube resonator devices hold promise for ultralow mass detection or quantum electromechanical experiments. However, the detection of the mechanical vibrations remains very challenging. In this talk, I will present a novel detection method of the vibrations of nanotubes and graphene, which is based on atomic force microscopy. This method enables the detection of the resonances up to 3.1 GHz with subnanometer resolution in vibration amplitude. Importantly, it allows the imaging of the mode-shape for the first eigenmodes. I will also report on a new artificial nanofabricated motor in which one short nanotube moves relative to another coaxial nanotube. The motion is shown to be controlled by how the atoms are arranged within the two nanotubes. The motion is actuated by imposing a thermal gradient along the device, allowing for sub-nanometer displacements. This is, to our knowledge, the first experimental demonstration of displacive actuation at the nanoscale by means of a thermal gradient. [Preview Abstract] |
Tuesday, March 17, 2009 11:51AM - 12:03PM |
J24.00002: Carbon nanotube based sharp tips and soldering irons Abha Misra, Chiara Daraio High energy electron beam machining has been proven a powerful tool to modify desired nanostructures for technological applications and to form molecular junctions and interconnections between carbon nanotubes. The development of the next generation of miniaturized electronic systems demands the integration of nanoelectronic components creating reliable mechanical and electrical contacts. At the same time, the development of scanning probe techniques and magnetic recording media require an ever decreasing tip size of ultrasharp magnetic read-write heads. We report on the nano-electron beam assisted fabrication of atomically sharp iron-based tips and on the creation of a nano-soldering iron for nano-interconnects using Fe-filled multiwalled carbon nanotubes (MWCNTs). Our technique allows also carving a MWCNT into a nanosoldering iron that was demonstrated capable of joining two separated halves of a tube. This approach could easily be extended to the interconnection of two largely dissimilar CNTs, between a CNT and a nanowire or between two nanowires. [Preview Abstract] |
Tuesday, March 17, 2009 12:03PM - 12:15PM |
J24.00003: Broken chiral symmetry in nanotube sliding Giuseppe Ernesto Santoro, Xiaohua Zhang, Ugo Tartaglino, Erio Tosatti We discovered, in simulations of the frictional sliding of coaxial nanotubes, an unanticipated example of dynamical symmetry breaking -- in fact a family of examples -- taking place at the nanoscale. While both nanotubes are armchair, thus perfectly left-right symmetric and nonchiral, a nonzero angular momentum appears spontaneously at a series of critical sliding velocities, in correspondence with large peaks of the sliding friction. The angular momentum is not connected with real bodily rotations, but rather to breathing phonon pseudorotations. The nonlinear equations governing this phenomenon turn out to share common elements with another classic problem exhibiting a dynamical chirality breaking, that of forced oscillations of a string or a rope. Several newer elements that are exquisitely ``nano'' appear in the nanotube case making it a richer, more elegant and intricate case, with a variety of different phenomena, and the crucial involvement of umklapp and of sliding nanofriction. [Preview Abstract] |
Tuesday, March 17, 2009 12:15PM - 12:27PM |
J24.00004: Porphyrin-like defects in CN$_x$ nanotubes Antonio J.R. da Silva, James Almeida, A.R. Rocha, A. Fazzio Carbon nanotubes (CNT) can be used in a variety of nanoscopic electronic devices, and their functionality can be greatly enhanced by the introduction of defects. It has been shown that CNTs doped with nitrogen atoms can act as sensors. Pyridine- like defects, where four N atoms surround a divacancy, have been shown [1] to act as binding sites of molecules, such as ammonia, and to be associated with the behavior of these sensors. In this work we study the adsorption of iron atoms onto these nitrogen defects. We demonstrate that the Fe atoms bind to the four N defect in a configuration similar to a porphyrin molecule. Moreover, this system - CN$_x$ nanotube plus iron atom - has a magnetic moment of 3 $\mu_B$ which is almost entirely localized on the Fe atom. With a combination of density functional theory and recursive Green's functions calculations we study the transport properties of disordered one-dimensional systems [1] composed of such units. In particular, we study the polarization of the current as a function of the average spin orientation of iron atoms randomly dispersed over the nanotubes in a reallistic setup. [1] A. R. Rocha, M. Rossi, A. Fazzio and A. J. R. da Silva, Phys. Rev. Lett. {\bf 100}, 176803 (2008). [Preview Abstract] |
Tuesday, March 17, 2009 12:27PM - 12:39PM |
J24.00005: Dislocation Onset and Glide in Carbon Nanotubes under Torsion Traian Dumitrica, Dong-Bo Zhang, Richard James The torsional plastic response of carbon nanotubes is comprehensively described in the objective molecular dynamics framework~[1-3]. It is shown that an (n,m) tube is prone to slip along a nearly-axial helical path, which introduces a distinct (+1,-1) change in the wrapping index. The low energy realization occurs without loss of mass, via nucleation of a 5-7-7-5 dislocation dipole, followed by a nearly-axial glide of the 5-7 dislocation. The onset of plasticity depends not only on chirality but also on handedness. For a given handedness of the applied twist, chiral tubes of opposed handedness are most susceptible to yield. A right-handed applied twist on an armchair (zig-zag) tube leads to a right- (left-) handed tube. \\[4pt] [1] T. Dumitric\u{a} and R.D. James, {\it Objective Molecular Dynamics}, Journal of the Mechanics and Physics of Solids {\bf 55}, 2206 (2007). \\[0pt] [2] D.-B. Zhang, M. Hua, and T. Dumitric\u{a}, {\it Stability of Polycrystalline and Wurtzite Si Nanowires via Symmetry-Adapted Tight-Binding Objective Molecular Dynamics}, Journal of Chemical Physics {\bf 128}, 084104 (2008). \\[0pt] [3] D.-B. Zhang and T. Dumitric\u{a}, {\it Elasticity of Ideal Single-Walled Carbon Nanotubes via Symmetry-Adapted Tight-Binding Objective Modeling}, Applied Physics Letters {\bf 93}, 031919 (2008). [Preview Abstract] |
Tuesday, March 17, 2009 12:39PM - 12:51PM |
J24.00006: Electrochemical Charging of Carbon Nanotubes for Tunable Electron Field Emission Cathodes Alexander Kuznetsov, Norman Barisci, Anvar Zakhidov, Alexander Zakhidov Carbon nanotubes (CNTs) have very promising applications as electron field emitters. Work function of CNTs greatly affects the performance of such cold electron emitters. It is possible to change emission currents by several orders of magnitude by electrochemical charging. Electrochemical charging changes work function of CNTs by creating so called double layer. It was recently demonstrated that double layer structure remains for several hours after removing the CNTs from an electrolyte [1]. The extensive study of charging single wall carbon nanotube (SWNT) paper in different electrolytes has been performed at different charging potentials Vch. Field emission currents and threshold fields dependence on the charging potential and polarity is studied for various ions, with different valency and size: Na, Mg, Cs. Clear dependence of work function on Vch is demonstrated. AFM micro-imaging with a Kelvin probe allowed to study the micropatterns of work function modulation. Also dissipation of positive charge in air was investigated and its stability was significantly increased. 1. Suh Dong-Seok, Baughman Ray, Zakhidov Anvar, US Patent 20070170071 (2007) [Preview Abstract] |
Tuesday, March 17, 2009 12:51PM - 1:03PM |
J24.00007: Interaction of water and methanol with graphene, C60 and (10,10) nanotube Vijay Kumar, M. Amar, J.F. Maguire, Y. Kawazoe We study interaction of water and methanol molecules with grapheme, C60 and (10,10) carbon nanotube using plane wave pseudopotential method and GGA. The interaction energies, $\Delta $E, of H2O and CH3OH molecules on a (10,10) SWCNT, C60 and a graphene sheet are quite small (a few tens of meV) and are weakly dependent on the orientation of the molecules. The different electronic structures of graphene, nanotubes, and C60 lead to the differences. For (10,10) nanotube $\Delta $E of water (39 meV) is favorable outside the nanotube and it increases for a water dimer. For methanol $\Delta $E outside as well as inside the nanotube is nearly the same (40 meV). A competition between molecules-molecule and molecule-nanotube wall interaction could, however, lead to interesting molecular ordering behavior. $\Delta $E of water on C60 is significantly smaller presumably due to its large HOMO-LUMO gap but for a graphene sheet the band gap vanishes and $\Delta $E has an intermediate value between C60 and (10,10) nanotube. For methanol on graphene sheet $\Delta $E increases to 60 meV due to more significant overlap of the molecular orbitals with those of the graphene sheet. [Preview Abstract] |
Tuesday, March 17, 2009 1:03PM - 1:15PM |
J24.00008: Hydrogen adsorption on metal coated Multiwalled Carbon nanotubes Xianfeng Zhang, Dinesh Rawat, Toyohisa Furuhashi, Rakesh Shah, Aldo Migone, Saikat Talapatra We present results of volumetric adsorption measurements of hydrogen, on Palladium-Gold (Pd-Au) coated multiwalled carbon nanotubes (MWNT). The nanotubes were prepared using air assisted chemical vapor deposition technique and were subsequently purified (acid treatment) before coating them with Pd-Au. Hydrogen adsorption measurements were performed at 77.3 K on as produced MWNTs as well as purified MWNT and compared with the adsorption isotherm obtained on Pd-Au coated MWNT samples under same experimental conditions. The effect of coating the MWNTs with Pd-Au on the adsorption behavior of hydrogen on these nanotubes will be discussed. [Preview Abstract] |
Tuesday, March 17, 2009 1:15PM - 1:27PM |
J24.00009: Enhancement of In Vivo Anticancer Effect of Cisplatin by Incorporation Inside Carbon Nanohorns Masako Yudasaka, Kumiko Ajima, Tatsuya Murakami, Yoshikazu Mizoguchi, Kunihiro Tsuchida, Toshinari Ichihashi, Sumio Iijima We have been studying potential applications of single-wall carbon nanohorns (SWNHs) to drug delivery systems. SWNHs are multiply functionalized with proteins, magnetites, tumor targeting molecules, and others. Various drugs are easily incorporated, and the incorporated drugs are slowly released. Almost no acute toxicity of SWNHs was found through various animal tests. We show in this report that anticancer effect of cisplatin was enhanced by incorporation inside SWNHs (CDDP@SWNH) as evidenced by in vivo tests: CDDP@SWNH was locally injected to tumors subcutaneously transplanted on mice. CDDP@SWNH inhibited the tumor growth more effectively than CDDP. This anticancer enhancement was achieved by large CDDP-quantity incorporated inside SWNH, slow release of CDDP from SWNH, long-term stay of SWNHs at the tumor sites, and an anticancer effect of SWNH itself [1].\\[3pt] [1] K. Ajima et al. ACSNano, 10(2008)2057-2064. [Preview Abstract] |
Tuesday, March 17, 2009 1:27PM - 1:39PM |
J24.00010: Fabrication of ZnPc/Protein Nanohorns for Double Photodynamic and Hyperthermic Cancer Phototherapy Minfang Zhang, Tatsuya Murakami, Kumiko Ajima, Kunihiro Tsuchida, Atula S. Sandanayaka, Osamu Ito, Sumio Iijima, Masako Yudasaka We developed double photodynamic and hyperthermic phototherapy systems [1] by loading zinc phthalocyanine (ZnPc) on single-wall carbon nanohorns (SWNHs). A protein of bovine serum albumin (BSA) was also attached to the surface of SWNHs. ZnPc performed photodynamic therapy (PDT) effect and SWNH had photohyperthermic (PHT) effect. BSA endowed hydrophilic property to the system. Previous results in vitro showed that the efficiency of phototherapy using ZnPc-SWNH-BSA was higher than that of ZnPc or SWNHs. We show in this report that mouse tests also exhibited the similar tendency. ZnPc-SWNH-BSA was locally injected in tumors subcutaneously transplanted on mice. And the laser (670 nm) was irradiated for 15 minute everyday for 10 days. By this phototherapy, the tumors completely disappeared. The phototherapy using ZnPc or SWNHox-BSA exhibited weaker antitumor effects, and the tumors continued to grow. [1] Zhang et al. PNAS, \textbf{2008}, 105, 14773. [Preview Abstract] |
Tuesday, March 17, 2009 1:39PM - 1:51PM |
J24.00011: Terahertz Plasmon Oscillations at Room Temperature in Nanotube Transistors Diego Kienle, Fran\c{c}ois L\'{e}onard We present a theoretical study of the high-frequency properties of carbon nanotube transistors. We employ a new theory for AC quantum transport based on a self-consistent Non-Equilibrium Green Function formalism. The theory is applied to calculate the frequency dependent response of a semi-conducting (17,0) nanotube FET device in the ballistic limit applying a time harmonic signal at the gate terminal. We show that in the ON- state the dynamical conductance exhibits divergent resonant peaks at discrete frequencies in the terahertz regime even at room temperature. These conductance peaks can be associated with the excitation of the charge eigenmodes (plasmons) of the quantum cavity formed by the nanotube channel and its surrounding gate, and shows up as pronounced spatial periodic large amplitudes in the AC charge and potential, respectively. The resonant features vanish when the device is operated in the OFF-state in which case the conductance displays smooth oscillations, a signature of single particle quantum interference. Our results indicate that low dimensional devices with nanometer channel length might show potential as novel detectors and emitters of THz radiation operating at room temperature. [Preview Abstract] |
Tuesday, March 17, 2009 1:51PM - 2:03PM |
J24.00012: Effects of substrate relaxation on adsorption in pores Silvina Gatica, Hye-Young Kim, George Stan, Milton Cole Fluids in porous media are commonly studied with analytical or simulation methods, usually assuming that the host medium is rigid. Large qualitative effects are found for several systems, for which substrate relaxation may not be neglected. One application is a determination of the ground state of 3He in slit and cylindrical pores. With the relaxation, there results a much stronger cohesion than would be found for a rigid host. Similar increased binding effects of relaxation are found for classical fluids confined within slit pores or nanotube bundles. These effects include large changes of the critical temperature (slit pore and nanotube bundle substrates) and condensation of the quasi-one dimensional fluid (carbon nanotube substrate). arXiv:0810.0262v1 [cond-mat.mtrl-sci] [Preview Abstract] |
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