Depth distribution of the fluorine concentration during radiative carbonization of PVDF

The XPS integral intensity of the F1s line and its satellite is measured during the long-term radiative carbonization of PVDF (polyvinylidene fluoride). A model is proposed that describes the effect of the fluorine depth distribution on the shape and intensity of the F1s spectra. A comparison of the experimental data with the model calculations provides estimates for the concentration inhomogeneity during the radiative carbonization of PVDF, for the photoelectron escape depth, and for the probability of a single energy loss by a photoelectron in its motion towards the surface. A technique determining the fluorine concentration is presented. It is based on the occurrence of chemical shifts of the C1s line towards larger bond energies for the carbon atoms chemically bonded to one or two fluorine atoms.