Quantum Conductance Steps in Solutions of Multiwalled Carbon Nanotubes

Abstract

We have prepared solutions of multiwalled carbon nanotubes in Aroclor 1254, a mixture of polychlorinated biphenyls. The solutions are stable at room temperature. Transport measurements were performed using a scanning-tunneling probe on a sample prepared by spin coating the solution on gold substrates. Conductance steps were clearly seen. A histogram of a high number of traces shows maximum peaks at integer values of the conductance quantum G(0)=2e(2)/h, demonstrating ballistic transport at room temperature along the carbon nanotube over distances longer than 1.4 microm.

Tomonaga-Luttinger Liquid and Coulomb Blockade in Multiwall Carbon Nanotubes under Pressure

“…We find that the ratio α end α bulk has a value of 2.4 ± 0.1, that varies little with pressure within our experimental error, as was also found for SWNT networks 21 . As for all other known mechanisms yielding power laws, this ratio 11,12 should be strictly = 2, this measurement again suggests a LL interpretation of region II. Furthermore, this ratio allows us to extract the value of the correlation parameter g = 0.16 ± 0.02 from the above expressions for α bulk and α end .…”

“…The first measurements on untreated individual MWNT's yielded neat ballistic single mode properties 6,7 . However, the majority of other measurements done on individual MWNT's have shown nonballistic properties 8,9,10,11 . As some carrier back-scattering is expected 12,13 High magnification scanning electron microscopy (SEM) analysis shows that the tubules grow out perpendicularly from the substrate and are evenly spaced at an averaged intertubule distance of ~100 nm, forming a highly aligned array.…”

Life cycle analysis of organic photovoltaic technologies

“…For the materials that are deposited using the spincoating method (PEDOT:PSS and P3HT:PCBM layers for our cells) we give two values for the material contained in the cell: (1) the minimum amount of material that should be used in order to fill the volume (area of cell times the thickness of the layer), taking into account for the calculation the reported densities of the materials: PCBM, with Mw ¼ 910.88, has a density of r PCBM ¼ 1.5 g/cm 3 ; P3HT (regioregular head-to-tail) with Mw ¼ 45000-65000, with r P3HT ¼ 1.11 g/cm 3 and PEDOT:PSS (1:25) with r PEDOT % 1 g/cm 3 ; and (2) the material amount used to prepare the solutions (3 wt%) in toluene (r toluene ¼ 0.862 g/ cm 3 ), which includes a big loss of material during the spincasting process that is scattered from the spinning substrates and not used in the final active layers. From comparison of this value with that given in Table XIX, and since we use 1 ml of solution to prepare five cells of 1 cm 2 in our experimental procedure, we can deduce a value for the 'material usage efficiency' of the spin-casting process, which results in a meagre 0.36% for the P3HT and PCBM, and a slightly better 0.45% for the PEDOT:PSS.…”

“…The material inventory and the energy embedded in the process will, however, not differ from other similar approaches which use blends of other functionalized carbon-based nanoparticles and conjugated polymers of other kind, such as derivatives of poly-paraphenylene-vinylene (PPV). For this technology, drawing on existing literature and the experience arising from our own device preparation method [3][4][5][6][7], a material inventory has been calculated, and the environmental impact of module fabrication (i.e. energy payback time and green house gas emissions) extrapolating the laboratory procedures towards an assumed large scale industrial production has also been calculated.…”

Rashba spin–orbit coupling and spin precession in carbon nanotubes

“…(26), which introduces right-and left-movers, r = ± = R/L, as the relevant low-energy degrees of freedom. For small deviations k from ±q n , Taylor expansion yields ǫ n (±q n + k) ≃ µ ± v n k, where v n is given in Eq.…”