Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 31: Organische Dünnschichten II

O 31.6: Vortrag

Donnerstag, 27. März 2003, 16:15–16:30, HSZ/02

Three dimensional growth of organic nanocrystals: A STM study — •Amin Bannani, Thorsten Wagner, Christian Bobisch, and Rolf Möller — Universität Essen, Fachbereich Physik, Institut für experimentelle Physik, 45117 Essen

An equivalent of ten monolayers of PTCDA (3,4,9,10-perylene-tetra-carboxylic-dianhydride) was deposited by OMBE on a Cu(111) single crystal. Annealing up to 520K leads to the formation of three dimensional PTCDA nanocrystals. These crystals were investigated by a home built STM, optimized for low tunnelling currents down to 1pA. Molecular resolution could be achieved as well on the top layer as on the slopes of the crystal consisting of 90 up to 100 molecular layers. It was possible to obtain the three-dimensional structure by evaluating the shift for each crystal-line relative to the unit cell in the top layer. It is found, that the structure of the nanocrystrals differs from the known bulk structures. The analysis was extended to PTCDA crystals found on different substrates, like Au(111) and Cu(110).