Quantification and IMFP determination of multilayer Langmuir-Blodgett films by AFM and XPS measurements

XPS spectra of cadmium arachidate Langmuir- Blodgett (LB) multilayer films have been investigated by quantitative peak shape and intensity analysis (the Tougaard method). The structure and film thickness of cadmium arachidate multilayer (1-21 layers) LB films on silicon wafers were observed by atomic force microscopy (AFM). The monolayer and bilayer thickness of cadmium arachidate LB film was determined to be 2.3 and 5.5 nm from AFM images of partially scratched multilayer LB films. The angle-resolved XPS (ARXPS) spectra of these LB films with well-defined thickness were analyzed by the Tougaard method. The inelastic mean free paths (IMFPs) in the LB film were determined to be 35.5 angstrom at 1382 eV and 29.1 angstrom at 1078 eV from analysis of ARXPS spectra taken at several emission angles (10 degrees, 32 degrees and 45 degrees from the surface normal). These values are in good agreement with the reported values of bulk organic materials. Copyright (C) 2006 John Wiley & Sons, Ltd.