The applicability of angle-resolved XPS to the characterization of clusters on surfaces

Monte Carlo simulations have been used to study the unexpected behavior of photoelectron intensity variations I(θ) as a function of take-off angle (angle-resolved XPS), generated by spherical Cu nanoclusters deposited on low permittivity insulators. Our results indicate that this behavior may be explained from the fact that the nanocluster morphology induces I(θ) contributions from both overlayer-like and substrate-like components, a situation that is more pronounced when the ratio of the particle radius to the electron attenuation length >1.