PESA in the analysis of hydrogen containing polymeric materials: Some basic considerations

The features and the analytical capability of particle elastic scattering analysis are investigated through a brief treatment of the kinematics of forward scattering and by conducting measurements with 3 MeV protons on hydrogen bearing polymeric foils at four different forward angles. The shape of the hydrogen signal in the proton spectrum is influenced strongly by multiple scattering. For other elements such as carbon or oxygen the influence, however, is rather weak or imperceptible. The proton spectra are simulated to obtain the atomic composition and the thickness of the foils. For polymers composed of hydrogen and carbon, measurements at any forward angles provide atomic composition with an accuracy of <10% while for those containing oxygen as well, measurements at angles ≥45° are more suitable. On the other hand, for the determination of thickness, measurements at higher forward angles are preferred due to kinematical reasons. The method is applied to 3.5–12 μm thick foils but can be extended to foils of higher thicknesses. With no perceptible damage to the targets at low (∼2 nA) beam currents, PESA is a simple, rapid and reliable method for the determination of elemental composition and thickness of self-supporting polymeric foils.