Model for Analysis of XPS Electron Take‐off Angle Experiments in Layer‐structured Samples: Determination of Attenuation Lengths in a Well‐characterized Langmuir–Blodgett Film

A series of equations have been proposed to calculate take-off angle dependency of the elemental composition of layer-structured models from the experimentally obtained peak intensities of XPS. We have measured the take-off angle dependency of XPS peaks of O 1s, C 1s, Si 2p and Cd 3d from a well-characterized one-layer Langmuir–Blodgett (LB) film of polymerized cadmium 10,12-pentacosadiynoate on a silicon wafer substrate and have applied the newly proposed equations to deduce attenuation lengths of photoelectrons for every element in the layer-structured organic materials. From the best fitting between the theoretically calculated and the experimentally obtained data by the least-squares method, attenuation lengths for a monolayer film of polymerized cadmium 10,12-pentacosadiynoate have been evaluated to be 3.4, 3.7, 4.0 and 4.5 nm for the respective photoelectrons of O 1s (955 eV), Cd 3d5/2 (1082 eV), C 1s (1202 eV) and Si 2p (1388 eV) with the kinetic energy dependency ofE0.75. It is essential to use polymerized LB films and to confirm the surface structure of the film directly by suitable techniques such as atomic force microscopy, scanning electron microscopy or transmission electron microscopy.© 1997 by John Wiley & Sons, Ltd.