Dresden 2006 – wissenschaftliches Programm
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O: Oberflächenphysik
O 24: Adsorption III
O 24.8: Vortrag
Dienstag, 28. März 2006, 17:30–17:45, TRE Phys
STM/STS investigations of Cu-phthalocyanine molecules on Al2O3/Ni3Al(111) — •A. Krupski1,2, M. Moors1, S. Degen1, M. Kralj1, C. Becker1, and K. Wandelt1 — 1Institute of Physical and Theoretical Chemistry, University of Bonn,Germany. — 2Institute of Experimental Physics, University of Wroclaw, Poland.
LT-STM and STS have been used to investigate the growth of Cu-phthalocyanine (C32H16N8Cu) molecules on an ultrathin Al2O3 oxide film grown on the Ni3Al(111) surface [1] as a function of coverage and annealing temperature. For sub- and monolayer coverage and a deposition temperature of 140 K two different planar molecular adsorption configurations rotated by 30o with respect to each other were observed with sub molecular resolution in the STM images. For θ CuPc about 1 ML, before completion of the first layer, the growth of a second layer was already observed. The measured distance of 0.35 nm between 1st and 2nd layer corresponds to the distance between layers in the a modification of crystalline CuPc. By the use of STS’ the lowest unoccupied molecular orbital (LUMO) of the adsorbed CuPc molecules has been identified at an energy of 1.2 eV. The lateral distribution of the electronic states of the CuPc has been analysed and mapped by STS. The C32H16N8Cu molecules grown at 140 are thermal stable up to 350 K against shape changes upon prolonged annealing to temperatures up to 350 K. A template effect of the underlying oxide film on the CuPc growth, as has been observed for metals like Pd [2], has not been found.
[1] S. Degen et al., Surf. Sci. Lett. 576 (2005) L57.
[2] S. Degen et al.,Faraday Discuss. 125 (2003) 343.