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Abstract

Monolayers of two different polyimides (PMDA-ODA and PMDA-PDA) have been prepared on graphite and oxidized silicon surfaces using the Langmuir-Blodgett (LB) technique of Kakimoto and co-workers. Scanning tunnelling microscopy indicates that both the rod-like PMDA-PDA and the zigzag PMDA-ODA are characterized by a high degree of two-dimensional order on graphite. X-ray absorption spectroscopy at the carbon, nitrogen and oxygen K-edges has been used to obtain information on the orientation of the different sections in the polymer chain. With the help of corresponding spectra from the model compounds pyromellitic diimide and diphenyl ether some insight can be gained into the origin of the resonances at the C and N K-edges.