Dresden 2006 – wissenschaftliches Programm

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O: Oberflächenphysik

O 25: Organic films II

O 25.1: Vortrag

Dienstag, 28. März 2006, 15:45–16:00, PHY C213

Electronic Effects in the Adsorption Structure of Organic Molecules: STM and STS of Phthalocyanines and Naphthalocyanines on Graphite — •Thiruvancheril G. Gopakumar and Michael Hietschold — Chemnitz University of Technology, Institute of Physics, Solid Surfaces Analysis Group, D-09107 Chemnitz, Germany.

The adsorption structure and electronic properties of various metal phthalocyanines and naphthalocyanies organized on graphite surface have been investigated using STM and STS. PdPc and PtPc show similar type of adsorption structure (quadratic lattice) although the central metal atoms are different, however PtPc (300^∘) adlayer shows almost three times thermal stability compared to PdPc (80-90^∘). Naphthalocyanine shows a distorted quadratic superstructure, the difference is expected in this case due to the long arms of the molecule (additional benzene ring) compared to phthalocyanine. The metal (Sn) naphthalocyanine shows quite interesting superstructure (hexagonal) compared to all other molecules studied may be due to the geometry (non-planar) arises due to the large Sn2+ ionic radious. These differences in the adsorption structures give insight in to how internal electrical properties of molecules affect the adsorption structure. Moreover we demonstrate the tip-sample distance dependant tunneling spectroscopy of these molecules which gives quantitative information about the electronic properties especially the transport at the molecule-substrate interface in the adlayer.