| 1. |
|
|
| 2. |
- Abou-Hamad, Edy, et al.
(författare)
-
Hydrogenation of C-60 in Peapods: Physical Chemistry in Nano Vessels
- 2009
-
Ingår i: The Journal of Physical Chemistry C. - WASHINGTON, DC 20036 : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 113:20, s. 8583-8587
-
Tidskriftsartikel (refereegranskat)abstract
- Hydrogenation of C-60 molecules inside SWNT was achieved by direct reaction with hydrogen gas at elevated pressure and temperature. Evidence for the C-60 hydrogenation in peapods is provided by isotopic engineering with specific enrichment of encapsulated species and high resolution C-13 and H-1 NMR spectroscopy with the observation of characteristic diamagnetic and paramagnetic shifts of the NMR lines and the appearance of sp(3) carbon resonances. We estimate that approximately 78% of the C-60 molecules inside SWNTs are hydrogenated to an average degree of 14 hydrogen atoms per C-60 molecule. As a consequence, the rotational dynamics of the encapsulated C60Hx molecules is clearly hindered. Our successful hydrogenation experiments open completely new roads to understand and control confined chemical reactions at the nano scale
|
|
| 3. |
- Abou-Hamad, Edy, et al.
(författare)
-
Molecular dynamics and phase transition in one-dimensional crystal of C60 encapsulated inside single wall carbon nanotubes
- 2009
-
Ingår i: ACS Nano. - Washington, DC 20036 USA : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 3:12, s. 3878-3883
-
Tidskriftsartikel (refereegranskat)abstract
- One-dimensional crystals of 25% 13C-enriched C60 encapsulated inside highly magnetically purified SWNTs were investigated by following the temperature dependence of the 13C NMR line shapes and the relaxation rates from 300 K down to 5 K. High-resolution MAS techniques reveal that 32% of the encapsulated molecules, so-called the C60α, are blocked at room temperature and 68%, labeled C60β, are shown to reversly undergo molecular reorientational dynamics. Contrary to previous NMR studies, spin−lattice relaxation time reveals a phase transition at 100 K associated with the changes in the nature of the C60β dynamics. Above the transition, the C60β exhibits continuous rotational diffusion; below the transition, C60β executes uniaxial hindered rotations most likely along the nanotubes axis and freeze out below 25 K. The associated activation energies of these two dynamical regimes are measured to be 6 times lower than in fcc-C60, suggesting a quiet smooth orientational dependence of the interaction between C60β molecules and the inner surface of the nanotubes.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Dzwilewski, Andrzej, et al.
(författare)
-
C60 Field-Effect Transistors: Effects of Polymerization on electronic Properties and Device Performance.
- 2007
-
Ingår i: Physical Review B. ; 75:7, s. 075203-
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated thin-film field-effect transistors (TFTs) with C60 as the active material, and we report the effects of photo-induced polymerization of the C60 film. We find that the effects of a complete polymerization for a typical top-contact C60 TFT is as follows: the electron mobility (μn) at room temperature drops slightly from 0.074 to 0.068 cm2/Vs, the activation energy of μn decreases from 0.10 meV to 0.09 meV, and the threshold voltage for TFT operation decreases markedly by ~15 %. The latter observation suggests that the effective number of electron traps in the C60 film decreases following polymerization. Considering that the polymerization was achieved with a low-energy HeNe laser, it is conceivable that the polymerization approach could be of interest for applications, e.g., organic bulk-heterojunction solar cells, where a stabilized C60 morphology attained with benign means is desired
|
|
| 7. |
- Dzwilewski, Andrzej, 1979-, et al.
(författare)
-
Photo-induced and resist-free imprint patterning of fullerene materials for use in functional electronics
- 2009
-
Ingår i: Journal of the American Chemical Society. - Washington, DC, USA : American Chemical Society. - 0002-7863 .- 1520-5126. ; 131:11, s. 4006-4011
-
Tidskriftsartikel (refereegranskat)abstract
- We report a novel and potentially generic method for the efficient patterning of films of organic semiconductors and demonstrate the merit of the method on the high-solubility fullerene [6,6]-phenyl C61- butyric acid methyl ester (PCBM). The patterning technique is notably straightforward as it requires no photoresist material and encompasses only two steps: (i) exposure of select film areas to visible laser light during which the PCBM mononer is photochemically converted into a dimeric state, and (ii) development via solvent washing after which the nonexposed portions of the PCBM film are selectively removed. Importantly, the method is highly benign in that it leaves the electronic properties of the remaining patterned material intact, which is directly evidenced by the fact that we fabricate fully functional arrays of micrometersized field-effect transistors with patterned PCBM as the active material.
|
|
| 8. |
|
|
| 9. |
- Iwasiewicz-Wabnig, Agnieszka, et al.
(författare)
-
Absence of an insulator-metal transition in Rb4C60 up to 2 GPa
- 2008
-
Ingår i: Physical Review B. - 0163-1829. ; 77:8, s. 085434-
-
Tidskriftsartikel (refereegranskat)abstract
- We present the results of direct resistance measurements on Rb4C60 under pressures up to 2 GPa. At all pressures covered by this study and over the temperature range of 90–450 K Rb4C60 is a semiconductor with a weakly pressure dependent band gap near 0.7 eV. We do not observe the insulator-to-metal transition previously reported to occur below 1.2 GPa, although we cannot rule out the possibility that such a transition might occur at some significantly higher pressure. The measured resistivity is surprisingly low and is dominated by carriers excited over a 0.1 eV gap. Because the corresponding conductivity increases with deformation of the sample, we assign these states to structural or orientational defects. The known structural transformation below 0.5 GPa leads to a decrease in resistivity under high pressure, but the material remains semiconducting. A Rb6C60 control sample showed a similar behavior, also being a semiconductor under all conditions studied. At temperatures above 460 K, Rb was partially lost from our samples, resulting in metallization by a transformation into Rb3C60.
|
|
| 10. |
- Iwasiewicz-Wabnig, Agnieszka, et al.
(författare)
-
Electrical resistance of Rb4C60 under pressure
- 2008
-
Ingår i: The Journal of Physics and Chemistry of Solids, vol. 69, issues 5-6. - Amsterdam : Elsevier B.V.. ; , s. 1218-1220
-
Konferensbidrag (refereegranskat)abstract
- We report the results of direct in situ resistance measurements of Rb4C60 under high pressure up to 2 GPa, in the temperature range 90–400 K. The resistance changes smoothly with pressure and temperature without sharp anomalies, and all data sets can be fitted to the same theoretical semiconductor model. We find no signs of the insulator-to-metal transition previously reported in this range, but the fitted band gap decreases with pressure and such a transition may possibly take place above 5 GPa.
|
|
