The structure and stability of metal surfaces modified by silane Langmuir-Blodgett films

Abstract

Monomolecular LB films of n-octadecyltrichlorosilane (n-OTS) and chlorodimethyloctadecylsilane (CODS) have been produced on metal substrates like Fe and Ni in order to protect the reactive metal surface against corrosive species like H 2O, O 2 and SO 2. To characterize defects within the monomolecular LB films, they were studied by UHV methods such as scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and scanning Auger microscopy (SAM). In dry or humid air atmospheres it is possible to measure a work function topography of the LB film covered materials with a scanning Kelvin microprobe. In dry air the work function topography corresponds to the distribution of dipole potentials. Therefore it is possible to analyze intrinsic defects within the monomolecular LB film on the metal surface. In a humid atmosphere the work function is mainly given by the local corrosion potential of the metal substrate and therefore delamination processes of the monomolecular film can be studied as well as the stability of the LB film coated metal substrate.