| 21. |
- Gromov, Andrei, 1959, et al.
(författare)
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Covalent Amino functionalisation of single walled carbon nanotubes
- 2005
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Ingår i: J. Materials Chem. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 15, s. 3334-3339
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Tidskriftsartikel (refereegranskat)abstract
- Chemical transformation of single-wall carbon nanotubes (SWNT), edge-terminated with carboxylic groups, to SWNT species with amino groups directly attached to the tube open ends has been performed. Different synthetic approaches have been investigated. The reaction products were characterised by FTIR, Raman spectroscopy, XPS and SEM.
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| 22. |
- Hansen, Klavs, 1958, et al.
(författare)
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Competition between fusion and intra-cluster fusion in highly excited fullerene clusters
- 2007
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Ingår i: Israel Journal of Chemistry. - 0021-2148. ; 47
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Tidskriftsartikel (refereegranskat)abstract
- The occurrence of intra-cluster fusion of fullerene molecules inside van der Waals bound fullerene clusters can be observed following femtosecond laser excitation. We show that the fusion reaction competes with the fission of multiply charged clusters. Energetic barriers to the reaction of at least 85 eV have to be overcome, similar to the energetic barriers to molecular fusion observed in fullerene ion–neutral fullerene collision experiments.
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| 23. |
- Hansen, Klavs, 1958, et al.
(författare)
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Do we know the value of the Gspann parameter?
- 2004
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Ingår i: Int.J.Mass Spectrom.. - : Elsevier BV. - 1387-3806. ; 233, s. 215-221
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Tidskriftsartikel (refereegranskat)abstract
- We reanalyze some of the data used by Klots to establish an experimental basis for the claim by Gspann that clusters have a highest temperature in molecular beams. The value of this temperature is given by the evaporative activation energy and a dimensionless parameter called the Gspann parameter. The value of the Gspann parameter we derive from the data is higher than the value found by Klots, and is consistent with the predictions from detailed balance theory, although a number of uncertainties persist. More recent data on oxygen clusters are analyzed with the same methods and the model dependent uncertainties are shown to be fairly large.
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| 24. |
- Hansen, Klavs, 1958, et al.
(författare)
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ISSPIC13 proceedings - Preface
- 2007
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Ingår i: Eur.Phys.J D. - 1434-6060. ; 43
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 25. |
- Hansen, Klavs, 1958, et al.
(författare)
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Laser power dependence in femtosecond ionization of fullerenes
- 2005
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 42, s. 282-285
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Tidskriftsartikel (refereegranskat)abstract
- Fullerene ionization can under some circumstances be modelled as thermal emission of electrons from a transiently hot electron gas. Application of this idea to experiments involving femtosecond lasers gave theoretical evidence for ion yields that would vary with the pulse energy of the laser to some power, identical to the behavior seen in multi-photon experiments. The reason for this behavior is investigated here. The crucial component is identified as the Poisson statistics for photon absorption and a strong variation of the ion yield with energy.
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| 26. |
- Hansen, Klavs, 1958, et al.
(författare)
-
The frequency factor in statistical fullerene decay
- 2006
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Ingår i: Int. J. Mass Spec.. - : Elsevier BV. - 1387-3806. ; 252, s. 79-95
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Tidskriftsartikel (refereegranskat)abstract
- Experiments on fullerene decay are reviewed and the frequency factor for C2 emission is extracted. The value is also calculated theoretically. Inclusion of a number of previously disregarded degrees of freedom for the products increase the theoretical estimate for C60 to above 1020 s−1, in good agreement with experimental results.
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| 27. |
- Hedén, Martin, 1976, et al.
(författare)
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Determination of the triplet state lifetime of vibrationally excited C-60
- 2003
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 118:16, s. 7161-7164
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Tidskriftsartikel (refereegranskat)abstract
- The lifetime of the ground triplet state of vibrationally excited C-60 has been determined in a two-color pump-probe experiment. An intense pump pulse (337 nm, 4 ns) was used to excite the neutral molecules. The triplet state was probed via single photon ionization with a weak probe pulse (193 nm). The lifetime was found to be on the order of 1 mus. This is rather low to explain recent delayed ionization results but higher than expected from an extrapolation of earlier measurements at lower temperatures. (C) 2003 American Institute of Physics.
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| 28. |
- Hedén, Martin, 1976, et al.
(författare)
-
Molecular Fusion of (C60)N Clusters in the Gas Phase after Femtosecond Laser Irradiation
- 2005
-
Ingår i: Phys. Rev. A. - 1050-2947. ; 71
-
Tidskriftsartikel (refereegranskat)abstract
- We report observation of molecular fusion of (C60)N+ clusters to form large fullerene molecules after excitation by 800-nm femtosecond laser pulses. The fused species decay by undergoing C2 fragmentation. Such fragmentation behavior for excited clusters of fullerene molecules can be understood in terms of the energetics of molecular fusion as determined previously from fullerene-fullerene collision experiments. Within a certain excitation energy window, there is sufficient time for a substantial atomic rearrangement to take place within the clusters before they dissociate. Below this energy window there is not sufficient internal energy for molecular fusion to occur while above the energy window multiple ionization followed by breakup of the clusters dominates.
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| 29. |
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| 30. |
- Hedén, Martin, 1976, et al.
(författare)
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Thermal radiation from CN+ and La@CN
- 2005
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Ingår i: J. Chem. Phys.. - : AIP Publishing. - 0021-9606. ; 123
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Tidskriftsartikel (refereegranskat)abstract
- The radiative cooling of positively charged fullerene and endohedral fullerene fragments of C60, C70, C84, and La@C82 has been measured in a time-of-flight mass spectrometer. The radiative cooling is measured via its influence on the metastable decay. The emissivity extracted from the data is between 4×10–4 and 13×10–4. These values agree fairly well with the emissivity calculated from considering the low-energy tail of the surface plasmon. No major difference is found in the emission behavior of empty and endohedral fullerenes.
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