Electron mean free paths as a function of kinetic energy: A substrate overlayer investigation of polyparaxylylene films on gold using A Ti Kα X-ray source

Abstract

Using the substrate overlayer technique with a Ti Kα 1,2 X-ray source (hν = 4510 eV) electron mean free paths λ have been determined for in situ deposited polyparaxylylene films. By monitoring the attenuation of signals arising from the substrate Au 4 f, 4 d, 4 p, 3 d and 3 p core levels excited by the Ti Kα X-ray source and for the Au 4 f and 4 d levels excited by Cu Lα X-rays (hν = 929.7 eV) mean free paths have been determined in the kinetic energy range ∼443–∼59O eV. The present results are compared with those reported previously for lower kinetic energies using Mg Kα 1,2 and Al Kα 1,2 photon sources. The results indicate that at kinetic energies of ∼4000 eV the typical sampling depth using a Ti Kα source is ∼ 150 Å.