Metal nanoparticle size distribution in hybrid organic/inorganic films determined by high resolution X-ray photoelectron spectroscopy

We report on the application of high resolution X-ray photoelectron spectroscopy (HR-XPS) to provide a fast identification of the size distribution of metal nanoparticles (NPs) embedded in a polymer matrix. An accurate spectral analysis was performed on the metal photoelectron core level to determine the specific calibration curve which relates the metal NP core level binding energy shift to its size, which was independently measured by transmission electron microscopy. We have fully characterized the binding energy shifts in the case of silver NPs on a polythiophene based polymer layer. This work shows how this procedure can be applied to characterize multimodal size distributions of metal NPs on a statistical adequate sample area, without having typical experimental limitations of a TEM experiment. Moreover, this technique can give access to chemical analysis and by alternating ion beam sputtering and XPS analysis, the NP diffusion along the growth direction can be revealed.