From clusters to fibers: Parameters for discontinuous para-hexaphenylene thin film growth
- Humboldt-Universitaet zu Berlin, Newtonstr. 15, D-12489 Berlin (Germany)
- Mads Clausen Institute, NanoSYD, Syddansk Universitet, DK-6400 Soenderborg (Denmark)
All relevant steps of discontinuous thin film growth of para-hexaphenylene on muscovite mica (0 0 1) from wetting layer over small and large clusters to nanofibers are observed and investigated in detail by a combined polarized fluorescence and atomic force microscopy study. From a variation of film thickness and surface temperature, we determine effective activation energies for cluster growth of 0.17 eV, for nanofiber length growth of 0.46 eV, for width growth of 0.19 eV, and for height growth of 0.07 eV. The corresponding exponential prefactors for the nanofiber growth are 1x10{sup 9}, 6x10{sup 4}, and 3x10{sup 2} nm. Polarized fluorescence studies reveal that nanofibers grow along the grooves of the mica surface and that they do not change direction if they cross an even number of mica surface steps, while they change direction by 120 deg. for an odd number of steps. These results are taken as an input for a model of the unidirectional growth process on mica. Absolute parameters allowing one to grow nanofibers of predetermined morphology via organic molecular beam epitaxy are also given.
- OSTI ID:
- 21103857
- Journal Information:
- Journal of Chemical Physics, Vol. 128, Issue 8; Other Information: DOI: 10.1063/1.2839296; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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