| 11. |
- Campbell, Eleanor E B, 1960, et al.
(författare)
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Ionisation of Fullerenes and Fullerene Clusters using Ultrashort Laser Pulses
- 2006
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Ingår i: Photochem. Photobiol. Sci.. - : Springer Science and Business Media LLC. - 1474-905X. ; 5, s. 1183 - 1189
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Tidskriftsartikel (refereegranskat)abstract
- We give a brief review of the literature concerning the ultra-short pulse ionisation of fullerenes in the gas phase. Emphasis is placed on the excitation time dependence of different ionisation regimes as manifested by photoelectron spectroscopy. The ionisation rates are modelled for the intermediate situation where the excitation energy is equilibrated between electronic degrees of freedom but not yet coupled to vibrational degrees of freedom. The model is shown to describe many aspects of the experiments. New results are presented on the intra-cluster molecular fusion of fullerene molecules when van der Waals bound clusters of fullerenes are exposed to ultra-short laser pulses. Pump–probe measurements give a decay time constant for the intra-cluster fusion reaction of 520 ± 55 fs. A comparison with monomer ionisation results suggests that the time window for the fusion reaction is influenced by the coupling of the electronic excitation energy to vibrational degrees of freedom of the molecules in the cluster.
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| 12. |
- Campbell, Eleanor E B, 1960
(författare)
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Nanotuben - elektronikens hopp
- 2004
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Ingår i: Forskning och Framsteg. - 0015-7937. ; :7, s. 20-23
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 13. |
- Ding, Feng, 1970, et al.
(författare)
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Graphitic encapsulation of catalyst particles in carbon nanotube production
- 2006
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 110:15, s. 7666-7670
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Tidskriftsartikel (refereegranskat)abstract
- A new model is proposed for the encapsulation of catalyst metal particles by graphite layers that are obtained, for example, in low-temperature chemical vapor deposition production of carbon nanotubes (CNTs). In this model graphite layers are primarily formed from the dissolved carbon atoms in the metal-carbide particle when the particle cools. This mechanism is in good agreement with molecular dynamics simulations (which show that precipitated carbon atoms preferentially form graphite sheets instead of CNTs at low temperatures) and experimental results (e.g., encapsulated metal particles are found in low-temperature zones and CNTs in high-temperature regions of production apparatus, very small catalyst particles are generally not encapsulated, and the ratio of the number of graphitic layers to the diameter of the catalyst particle is typically 0.25 nm(-1)).
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| 14. |
- Dittmer, Staffan, 1970, et al.
(författare)
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Electric field aligned growth of single-walled nanotubes
- 2004
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Ingår i: Current Applied Physics. - : Elsevier BV. - 1567-1739. ; 4, s. 595-598
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Tidskriftsartikel (refereegranskat)abstract
- Electric field aligned, single-walled carbon nanotubes are grown between electrodes using thermal chemical vapour deposition (CVD) of methane. The growth occurs on a thin film layered catalyst of aluminium, iron and molybdenum patterned on top of electrodes. The nanotubes bridge 10 μm sized electrode gaps and have a typical diameter of less than 2 nm as measured by Raman spectroscopy and atomic force microscopy. We present electrical transport measurements on a directly grown nanotube which shows p-type semiconducting behaviour.
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| 15. |
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| 16. |
- Dittmer, Staffan, 1970, et al.
(författare)
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In situ Raman studies of single-walled carbon nanotubes grown by local
- 2008
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 457
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Tidskriftsartikel (refereegranskat)abstract
- Using in situ Raman spectroscopy we investigate single wall carbon nanotube growth on Mo electrodes, using a highly localized resistive heating technique. Small diameter semiconducting single wall nanotubes grow very rapidly when the catalyst support is heated to a temperature of 800 C. The G/D ratio shows an interesting time-dependent behaviour. It first decreases, indicating the presence of amorphous carbon and then significantly increases again after ca. 5 min growth while retaining the position and shape expected for predominantly semiconducting carbon nanotubes.
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| 17. |
- Dittmer, Staffan, 1970, et al.
(författare)
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Local heating method for growth of aligned carbon nanotubes at low ambient temperature
- 2008
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Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 34:10, s. 834-838
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Tidskriftsartikel (refereegranskat)abstract
- We use a highly localised resistive heating technique to grow vertically aligned multiwalled nanotube films and aligned single-walled nanotubes on substrates with an average temperature of less than 100oC. The temperature at the catalyst can easily be as high as 1000 oC but an extremely high temperature gradient ensures that the surrounding chip is held at much lower temperatures, even as close as 1μm away from the local heater. We demonstrate the influence of temperature on the height of multi-walled nanotube films, illustrate the feasibility of sequential growth of single-walled nanotubes by switching between local heaters and also show that nanotubes can be grown over temperature sensitive materials such as resist polymer.
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| 18. |
- Dittmer, Staffan, 1970, et al.
(författare)
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Low ambient temperature CVD growth of carbon nanotubes
- 2006
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Ingår i: Applied Physics A. - : Springer Science and Business Media LLC. - 0947-8396 .- 1432-0630. ; 84, s. 243-246
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Tidskriftsartikel (refereegranskat)abstract
- We show that good quality single-walled and multi-walled carbon nanotubes can be grown on CMOS-compatible metal electrodes at ambient room temperature using highly localised catalyst heating at nanostructured electrodes. The method is relatively straightforward and allows considerable flexibility in the kinds of devices that can be fabricated as well as allowing CVD nanotube growth to take place in the close vicinity of temperature-sensitive materials and devices.
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| 19. |
- Dong Su, Lee, et al.
(författare)
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Quantum dot manipulation in a single-walled carbon nanotube using a carbon nanotube gate
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89:23, s. 233107-1
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Tidskriftsartikel (refereegranskat)abstract
- Cross junctions of carbon nanotubes (CNTs) separated by thin oxide layers have been fabricated, in which the top CNT is used as a local gate to control the electron transport through the lower CNT. Coulomb oscillation was observed in the lower CNTs at low temperatures. The gating field from the upper CNTs is seen to modulate the band structure in the lower CNTs, producing double quantum dot systems. The ability to modulate the electronic structure of CNTs in such a way opens up many possibilities for future electronic and logical nanodevices
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| 20. |
- Eriksson, Anders, 1975, et al.
(författare)
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Direct Transmission Detection of Tunable Mechanical Resonance in an Individual Carbon Nanofiber Relay
- 2008
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- A direct on-chip transmission measurement of the resonance frequency of an individual singly clamped carbon nanofiber relay is reported. The experimental results are in good agreement with a small signal model and show the expected tuning of the resonance frequency with changing bias voltage.
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