Damage of polyvinylalcohol by 16 MeV electrons

Abstract

Abstract A stack of seven 15 μ thick polyvinlyl alcohol (PVA) foils was irradiated with 16 MeV electrons. In order to allow for the electrons’ slowing-down until stopping, six 5 mm thick Al plates had been inserted in between these PVA foils. The fractional depth distribution of the PVA destruction is derived from the change in the UV-Vis optical spectrum of PVA with depth. The polymer irradiation leads to a shift in the optical absorption edges, which indicates a lowering of the energy gap. A convenient explanations of this change is to assume the formation of carbonaceous clusters. The sizes of these clusters are estimated according to Robertson's theory. Their growth with increasing mean transferred energy density is compared with the one recorded after ion irradiation. For the same transferred energy density, energetic electrons are found to be slightly less efficient in polymer damage than energetic ions.