XPS and AFM surface study of PMMA irradiated by electron beam

The effect of low energy electron (LEE) irradiation on polymethylmethacrylate (PMMA) film has been studied. The PMMA film of thickness 20 μm is exposed by a 10 keV electron beam with fluence 2 × 1014 e/cm2. The irradiated film was characterized by X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM). The significant changes in the chemical composition of the surface layer were confirmed by XPS quantitatively. The scission of the chain in the surface layer of PMMA film was induced by electron irradiation and the atomic ration (O1s/C1s) was decreased. This phenomenon is responsible for the creation of carbon-rich surface layer. TM-AFM showed hills of nano size surrounded by crater-type features on the irradiated film. The root-mean-square (rms) surface roughness of the sample increased from 3.715 nm to 5.020 nm due to the irradiation, which shows that the surface became rougher after irradiation.