Dresden 2003 – wissenschaftliches Programm
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O: Oberflächenphysik
O 31: Organische Dünnschichten II
O 31.7: Vortrag
Donnerstag, 27. März 2003, 16:30–16:45, HSZ/02
Structural and optical investigations of ultrathin tetracene films on Ag(111) — •Andreas Langner, Sonja Fahrenholz, Annegret Hauschild, and Moritz Sokolowski — Institut für Physikalische und Theoretische Chemie, Universität Bonn, Wegelerstr. 12, D-53115 Bonn
Ultrathin tetracene films (1-30 ML) grown on Ag(111) by vacuum sublimation under UHV were studied in order to investigate the influence of the Ag(111) interface on their structural and optical properties.
LEED patterns for both mono- and multilayers are identical. We explain this by a Stranski-Krastanov growth type with small clusters on a closed monolayer of tetracene. The monolayer structure is commensurate in higher order to the substrate. Two peaks were observed in the thermodesorption spectra which can be assigned to the multi- and monolayer. The desorption is of zero order and the leading edge analysis yields a desorption energy of (124 ± 1) kJ mol−1 which is in good agreement to the sublimation enthalpie of tetracene (113 ± 3) kJ mol−1. The photoluminescence spectra differ from those of bulk material. They are composed from at least two components. The relative intensity of these components changes drasticly as a function of temperature and probably indicates a reversible phase transition at a temperature of 110 K.
Supported by the DFG.