41.
Quantum pumps formed of double walled carbon nanotubes
Zólyomi, V.; Oroszlány, L.; Lambert, C. J.
Physica status solidi. B. Basic research,
December 2009, Letnik:
246, Številka:
11‐12
Journal Article, Conference Proceeding
Using the Brouwer formula, we employ Green's function technique to study charge pumping in shuttle geometry double walled carbon nanotubes. We find strong chirality dependence, and that there is ...
virtually no pumping if the chiral angle of the two walls is the same. We discuss which are the optimal chiralities that can be used for such quantum pumps. Furthermore, we argue that charge pumping with double walled tubes can be used to probe the strength of the inter‐layer coupling between the inner and outer nanotube.
več
Dostopno za:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
42.
Dostopno za:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
43.
Semiconductor-to-metal transition of double walled carbon nanotubes induced by inter-shell interaction
Zólyomi, V.; Rusznyák, Á.; Kürti, J. ...
Physica Status Solidi (b),
November 2006, Letnik:
243, Številka:
13
Journal Article, Conference Proceeding
Nuclear magnetic resonance measurements on isotope engineered double walled carbon nanotubes (DWCNT) suggest a uniformly metallic character of all nanotubes. This effect can only be explained by the ...
interaction between the inner and outer shell. Here we study the DWCNTs by density functional theory and inter‐molecular Hückel model. We present a study of the density of states of DWCNTs which clearly shows that two layers of semiconducting single walled nanotubes can indeed form a metallic DWCNT in many cases, but not necessarily in every case. For most metallic DWCNTs, a high density of states can be expected at the Fermi level. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
več
Dostopno za:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
44.
The electronic band structure of fullerene-cubane cocrystals
Zólyomi, V.; Koltai, J.; Kürti, J. ...
Physica Status Solidi (b),
October 2008, Letnik:
245, Številka:
10
Journal Article, Conference Proceeding
We present a first principles study of the electronic band structure of fullerene‐cubane (C60C8H8) cocrystals, using density functional theory at the local density approximation level. The band ...
structure is calculated along high symmetry lines and compared to that of the fcc fullerene. A contraction of the fullerene bands is found and is attributed to the expansion of the lattice caused by the presence of cubane. Charge transfer between the components of C60C8H8 is also calculated by Bader charge analysis. The possibility of a very small charge transfer between the cubane and the fullerene is discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
več
Dostopno za:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
45.
Electron spin resonance in alkali doped SWCNTs
Simon, F.; Galambos, M.; Quintavalle, D. ...
Physica Status Solidi (b),
October 2008, Letnik:
245, Številka:
10
Journal Article, Conference Proceeding
Electron spin resonance (ESR) measurements on SWCNTs doped with alkali atoms (potassium) using a solid state reaction is reported. We find the emergence of the ESR signal of itinerant electrons upon ...
doping with a signal intensity that is comparable to that expected from band structure calculations.
The ESR line‐width and microwave conductivity weakly depend on the temperature indicating that doped SWCNTs are bad metals. It is argued to result from the lack of crystalline order in the tubes and the large impurity concentration. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
več
Dostopno za:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
46.
Curvature effects in the D band of small diameter carbon nanotubes
Kürti, J.; Zólyomi, V.; Koltai, J. ...
Physica Status Solidi (b),
November 2007, Letnik:
244, Številka:
11
Journal Article, Conference Proceeding
The energy dispersion of the D* (G′) band shows a strong diameter dependence according to Raman measurements on double walled carbon nanotubes. The Raman shift of the small diameter inner tubes shows ...
an average softening. There is an oscillation around an average linear behavior with slopes of 108 cm–1/eV and 61 cm–1/eV for the outer and inner tubes, respectively. We show that the experimental observation can be reproduced by simple model calculations if the curvature effects are taken into account. The phonon softening with increasing curvature was proven by first principles calculations. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
več
Dostopno za:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
47.
Double walled carbon nanotube with the smallest inner diameter: a first principles study
Kürti, J.; Zólyomi, V.; Yang, S. ...
Physica Status Solidi (b),
November 2006, Letnik:
243, Številka:
13
Journal Article, Conference Proceeding
The smallest possible inner tube diameter in a double walled carbon nanotube is the zero diameter inner tube, in other words, an infinite linear carbon chain. In this work, we present a first ...
principles study of the vibrational properties of the infinite carbon chain, employing a novel linear/exponential scaling scheme based on the intrinsic behavior of the long range force constant couplings in quasi one‐dimensional chains. The longitudinal optical Raman active frequency is predicted at 1870–1877 cm–1, in contrast to the widely accepted values in the 2000–2200 cm–1 range. Our results provide further evidence for the assignment of the characteristic Raman peaks near 1850 cm–1 of the recently discovered long linear carbon chains encapsulated inside multi‐walled or double walled carbon nanotubes. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
več
Dostopno za:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
48.
The effects of inhomogeneous isotope distribution on the vibrational properties of isotope enriched double walled carbon nanotubes
Zólyomi, V.; Simon, F.; Rusznyák, Á. ...
Physica status solidi. B. Basic research,
November 2007, Letnik:
244, Številka:
11
Journal Article, Conference Proceeding
The radial breathing mode in the Raman spectrum of 13C isotope enriched single walled carbon nanotubes is inhomogeneously broadened due to the random distribution of isotopes. We study this effect ...
theoretically using density functional theory within the local density approximation and compare the result with experiments on isotope engineered double walled carbon nanotubes in which the inner tubes were grown from a mixture of 13C enriched fullerenes and natural fullerenes. As explained by the calculations, this synthesis procedure leads to an increased inhomogeneity compared to a case when only enriched fullerenes are used. The good agreement between the measurements and calculations shows the absence of carbon diffusion along the tube axis during inner tube growth, and presents a strong support of the theory that inner tube growth is governed by Stone–Wales transformations following the interconnection of fullerenes. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
več
Dostopno za:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
49.
Enhancement of electron-nuclear hyperfine interaction at lattice defects in semiconducting single-walled carbon nanotubes studied by ab initio density functional theory calculations
Zólyomi, V.; Ivády, V.; Gali, A.
Physical review. B, Condensed matter and materials physics,
12/2012, Letnik:
86, Številka:
23
Journal Article
We present a first principles study of the electron-nuclear hyperfine-interaction (HF) in achiral single-walled carbon nanotubes (SWCNTs). We show that while HF coupling is small in perfect ...
nanotubes, it is significantly enhanced near lattice defects such as vacancies and Stone-Wales pairs. The enhancement of hyperfine coupling near the defects varies considerably in different nanotubes which might pave the way to simultaneously identifying the chirality of carbon nanotubes and the defects inside them by sophisticated magnetic resonance techniques. Charged vacancy is proposed as a candidate for solid state qubit in semiconducting SWCNTs.
več
Dostopno za:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
50.
Controlled Isotope Arrangement in 13C Enriched Carbon Nanotubes
Koltai, J; Mezei, G; Zólyomi, V ...
Journal of physical chemistry. C,
12/2016, Letnik:
120, Številka:
51
Journal Article
We report the synthesis of a novel isotope engineered 13C–12C heteronuclear nanostructure: single-wall carbon nanotubes made of 13C enriched clusters which are embedded in natural carbon regions. The ...
material is synthesized with a high temperature annealing from 13C enriched benzene and natural C60, which are coencapsulated inside host SWCNTs in an alternating fashion. The Raman 2D line indicates that the 13C isotopes are not distributed uniformly in the inner tubes. A semiempirical method based modeling of the Raman modes under 13C isotope enrichment shows that experimental data is compatible with the presence of 13C rich clusters which are embedded in a natural carbon containing matrix.
več
Dostopno za:
IJS, KILJ, NUK, PNG, UL, UM
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