Mechanically induced current and quantum evaporation from Luttinger liquids

We investigate transport through a tunnelling junction between an uncorrelated metallic lead and a Luttinger liquid when the latter is subjected to a time dependent perturbation. The tunnelling current as well as the electron energy distribution function are found to be strongly affected by the perturbation due to generation of harmonics in the density oscillations. Using a semiconducting lead instead of a metallic one results in electrons being injected into the lead even without applied voltage. Some applications to carbon nanotubes are discussed.Comment: 7 pages, 2 figures (eps files

Carbon Nanotubes as Nanoelectromechanical Systems

We theoretically study the interplay between electrical and mechanical properties of suspended, doubly clamped carbon nanotubes in which charging effects dominate. In this geometry, the capacitance between the nanotube and the gate(s) depends on the distance between them. This dependence modifies the usual Coulomb models and we show that it needs to be incorporated to capture the physics of the problem correctly. We find that the tube position changes in discrete steps every time an electron tunnels onto it. Edges of Coulomb diamonds acquire a (small) curvature. We also show that bistability in the tube position occurs and that tunneling of an electron onto the tube drastically modifies the quantized eigenmodes of the tube. Experimental verification of these predictions is possible in suspended tubes of sub-micron length.Comment: 8 pages, 5 eps figures included. Major changes; new material adde

Pumping current of a Luttinger liquid with finite length

We study transport properties in a Tomonaga-Luttinger liquid in the presence of two time-dependent point like weak impurities, taking into account finite-length effects. By employing analytical methods and performing a perturbation theory, we compute the backscattering pumping current (I_bs) in different regimes which can be established in relation to the oscillatory frequency of the impurities and to the frequency related to the length and the renormalized velocity (by the electron-electron interactions) of the charge density modes. We investigate the role played by the spatial position of the impurity potentials. We also show how the previous infinite length results for I_bs are modified by the finite size of the system.Comment: 9 pages, 7 figure

Aggregate structure of hydroxyproline-rich glycoprotein (HRGP) and HRGP assisted dispersion of carbon nanotubes

Hydroxyproline-rich glycoproteins (HRGP) comprise a super-family of extracellular structural glycoproteins whose precise roles in plant cell wall assembly and functioning remain to be elucidated. However, their extended structure and repetitive block co-polymer character of HRGPs may mediate their self-assembly as wall scaffolds by like-with-like alignment of their hydrophobic peptide and hydrophilic glycopeptide modules. Intermolecular crosslinking further stabilizes the scaffold. Thus the design of HRGP-based scaffolds may have practical applications in bionanotechnology and medicine. As a first step, we have used single-molecule or single-aggregate atomic force microscopy (AFM) to visualize the structure of YK20, an amphiphilic HRGP comprised entirely of 20 tandem repeats of: Ser-Hyp4-Ser-Hyp-Ser-Hyp4-Tyr-Tyr-Tyr-Lys. YK20 formed tightly aggregated coils at low ionic strength, but networks of entangled chains with a porosity of ~0.5–3 μm at higher ionic strength. As a second step we have begun to design HRGP-carbon nanotube composites. Single-walled carbon nanotubes (SWNTs) can be considered as seamless cylinders rolled up from graphene sheets. These unique all-carbon structures have extraordinary aromatic and hydrophobic properties and form aggregated bundles due to strong inter-tube van der Waals interactions. Sonicating aggregated SWNT bundles with aqueous YK20 solubilized them presumably by interaction with the repetitive, hydrophobic, Tyr-rich peptide modules of YK20 with retention of the extended polyproline-II character. This may allow YK20 to form extended structures that could potentially be used as scaffolds for site-directed assembly of nanomaterials

Crystalline Networks With Unusual Predicted Mechanical And Thermal Properties

MOST materials shrink laterally and become less dense when stretched. Materials that both expand laterally (that is, have negative Poisson's ratio) and densify when stretched are of interest both from the fundamental and the practical points of view1-5. A few monocrystalline phases with negative Poisson's ratio are known3,4, but these do not densify when stretched. Here we present molecular-mechanics calculations for some hypothetical phases of carbon which exhibit both kinds of behaviour. The properties derive from the presence of bonds that act as hinges in extended helical chains. Other unusual properties of these phases include negative thermal expansion, dopant-controlled porosity and low-temperature polymorphism. Such structures can be envisaged for polyacetylene, polydiacetylene, polyphenylene and (BN)x phases, as well as for variants of some known, structurally related inorganic phases.365644873473

Negative Volumetric Thermal Expansion For Proposed Hinged Phases

Negative volumetric thermal expansion coefficients are predicted by molecular dynamics calculations for members of a broad family of materials based on three-connected, three-dimensional networks. This unusual feature, as well as novel mechanical properties, is a result of a soft shear deformation mode resulting from rotations about parallel bonds that serve as hinges. The investigated hinged phases include carbon and hydrocarbon phases based on polyacetylene and polyacene chains and on graphite sheets. © 1995.2401-3180184Shah, Straumanis, (1972) Solid State Commun., 10, p. 159Chu, Saka, Suh, (1987) Mater. Sci. Eng., 95, p. 303Tummala, (1976) J. Mater. Sci., 11, p. 125Baughman, Galvão, (1993) Nature, 365, p. 735Wells, The geometrical basis of crystal chemistry. XII. Review of structures on three-dimensional 3-connected nets (1976) Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 32, p. 2619Hoffmann, Hughbanks, Kertész, Bird, (1983) J. Am. Chem. Soc., 105, p. 4831Liu, Cohen, Theoretical study of a hypothetical metallic phase of carbon (1991) Physical Review B, 45, p. 4579Guo, Karasawa, Goddard, (1991) Nature, 351, p. 464Allinger, Sprague, (1973) J. Am. Chem. Soc., 95, p. 3893Kao, Allinger, (1977) J. Am. Chem. Soc., 99, p. 975Berendsen, Postma, van Gunstem, DiNola, Haak, (1984) J. Chem. Phys., 81, p. 3684Baughman, Turi, (1973) J. Polym. Sci. Polym. Phys. Ed., 11, p. 2453Diederich, Rubin, (1992) Angew. Chem. Intern. Ed. Engl., 31, p. 1101Wu, Lee, Moore, (1992) J. Am. Chem. Soc., 114, p. 8730Klepp, Parthé, RPtSi phases (R = La, Ce, Pr, Nd, Sm and Gd) with an ordered ThSi2 derivative structure (1982) Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 38, p. 110

Tubulanes: Carbon Phases Based On Cross-linked Fullerene Tubules

Structure and properties are calculated for five predicted carbon phases, called tubulanes, which are shown to be possible reaction products of single-layer and multiple-layer carbon tubules. Each carbon atom is equivalent and in a modified sp3 state in these phases which contain column structures that are directly related to those in either armchair or zig-zag carbon tubules. One such phase has a predicted bulk modulus which is within 6% of that of diamond, and a predicted heat of formation which is much lower than for either the C60 fullerene or other previously characterized no-diamond-like phases containing only sp3 carbons. © 1993.2111110118Iijima, (1991) Nature, 354, p. 56Ebbesen, Ajayan, (1992) Nature, 358, p. 220Ajayan, Iijima, (1992) Nature, 358, p. 23Saito, Fujita, Dresselhaus, Dresselhaus, (1992) Appl. Phys. Letters, 60, p. 2204Endo, Kroto, (1992) J. Phys. Chem., 96, p. 6941Burdett, Lee, (1985) J. Am. Chem. Soc., 107, p. 3063Johnston, Hoffmann, (1989) J. Am. Chem. Soc., 111, p. 810Lagua, Musso, Boland, Ahlrichs, Force field calculations (MM2) of carbon lattices (1990) Journal of the American Chemical Society, 112, p. 7391Fahy, Louie, (1987) Phys. Rev., 36 B, p. 3373Balaban, Rentia, Ciupitu, (1968) Rev. Rom. Chim., 13, p. 231O'Keefe, (1991) Nature, 352, p. 674Bundy, Kasper, (1967) J. Chem. Phys., 46, p. 3437Utsumi, Yagi, Formation of Hexagonal Diamond by Room Temperature Compression of Graphite. (1991) Proceedings of the Japan Academy. Ser. B: Physical and Biological Sciences, 67 (B), p. 159Nunez-Rugueiro, C60UNDER PRESSURE (1992) Modern Physics Letters B, 6 B, p. 1153. , and references thereinYoo, Nellis, (1992) Chem. Phys. Letters, 198, p. 379Moshary, Chen, Silvera, Browy, Dorn, de Vries, Bethone, (1992) Phys. Rev. Letters, 69, p. 466McCullough, (1987) Chem. Rev., 87, p. 811Hoke, Molstad, Diletlato, Jay, Carlson, Kahr, Cooks, (1992) J. Org. Chem., 57, p. 5069W.A. Goddard and N. Karasawa, J. Phys. Chem., submitted for publicationGuo, Karasawa, Goddard, (1991) Nature, 351, p. 464Allinger, (1977) J. Am. Chem. Soc., 99, p. 8127Hawtin, Lewis, Moul, Phillips, The Heats of Combustion of Graphite, Diamond and Some Non-Graphitic Carbons (1966) Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 261, p. 67Wiberg, The Concept of Strain in Organic Chemistry (1986) Angewandte Chemie International Edition in English, 25, p. 312. , Intern. Ed. EnglEaton, (1992) Angew. Chem., 31, p. 1421. , Intern. Ed. EnglGrimsditch, Ramdas, (1975) Phys. Rev., 11 B, p. 3139Duclos, Brister, Haddon, Kordan, Thiel, (1991) Nature, 351, p. 380Steele, Chirico, Smith, Billups, Elmore, Wheeler, (1992) J. Phys. Chem., 96, p. 4731Robertson, Brenner, Mintmire, (1992) Phys. Rev., 45 B, p. 12592Adams, Sankey, Page, O'Keeffe, Drabold, (1992) Science, 256, p. 1792Metha, Viswanath, Sastry, Jemmis, Reddy, Kunwar, Quest for Higher Ladderanes: Oligomerization of a Cyclobutadiene Derivative (1992) Angewandte Chemie International Edition in English, 31, p. 1488. , Intern. Ed. EnglHutmacher, Fritz, Musso, Tetraasterane, Pentacyclo[6.4.0.02,7.04,11.05,10]dodecane (1975) Angewandte Chemie International Edition in English, 14, p. 180. , Intern. Ed. EnglMeir, Olson, (1992) Atlas of zeolite structure types, , 3rd Ed., Butterworth-Heinemann, LondonWells, (1977) Three dimensional nets and polyhedra, pp. 104-138. , Wiley, New York, ch. 9Housmans, Honnef, Über einige neue Modifikationen des Kohlenstoffs (1984) Nachrichten aus Chemie, Technik und Laboratorium, 32, p. 379Jose-Yacaman, Miki-Yosida, Rendon, Santiesteban, Catalytic growth of carbon microtubules with fullerene structure (1993) Applied Physics Letters, 62, p. 202McMurry, Haley, Matz, Clardy, Duyne, Gleiter, Schater, White, (1986) J. Am. Chem. Soc., 108, p. 2932Kosakovskaya, Chemozatonskii, Fedorov, (1992) JETP Letters, 56, p. 2

ELECTROCHEMICAL CELLS EMPLOYING POLYACETYLENE AND POLY(p-PHENYLENE) AS ACTIVE MATERIALS

Le comportement électrochimique du poly-acétylène et du poly(p-phénylène) est discuté en fonction de la structure de bande et de la structure cristalline.The electrochemical behavior of polyacetylene and poly(p-phenylene) is discussed in terms of band-structure and crystal structure

Vibrational spectra and structure of undoped polyparaphenilene

Infrared and Raman spectroscopic data on undoped and AsF5-doped polyparaphenylene (PPP), are presented. The results are discussed in terms of the normal mode calculation of Rakovic et al and the bipolaron defect mode1 of the doped polymer proposed by Bredas et al