Attenuation lengths of photoelectrons in hydrocarbon films

Abstract

Abstract : Quantitative analysis of data obtained by X-ray photoelectron spectroscopy (XPS) requires a knowledge of the escape depths of electrons from the surface of a sample. In order to derive the composition of a homogeneous material from the intensities of the photoelectrons originating from different elements, one needs to know not only the relative atomic cross-sections, but also the variation of the attenuation length, gamma, with the energy of the photoelectrons. The ability to derive an elemental depth profile of a layered material from the variation in the photoelectron intensity with the angle of emission requires a knowledge of the absolute value of gamma. The recent growth of interest in thin organic films has generated an immediate need for accurate, reliable values of gamma in organic materials in general, and in thin, densely packed hydrocarbon films in particular. In this paper we have determined the attenuation length of electrons with energies in the range 940-1400 eV in self- assembled monolayers of n-alkanethiols adsorbed on gold. (JS)