Elucidation of the Two-Step Damage Formation Process of Latent Tracks in Poly(allyl diglycol carbonate), PADC: Role of Secondary Low-Energy Electrons

The aim of the present study is to evaluate the mechanisms by which secondary electrons of low energy degrade poly(allyl diglycol carbonate) (PADC) when it is used as a Solid State Nuclear Track Detector. We measured, by time-of-flight mass spectrometry, the positive and negative ions desorbed by the impact of 5-30 eV electrons on three monolayer thick films of various PADC surrogate molecules, which contained ether and/or carbonyl (C=O) moieties. As cleavages within the molecules progress, most anion yields are seen to decrease with an increasing cumulative number of incident electrons (i.e., fluence). In contrast, the yield of O- at incident energies >15 eV, which is associated with damage at a carbonyl group, increases monotonically with fluence. This finding implies that cleavage of carbonyl groups occurs after damage to other oxygen containing groups within the surrogates. The present result corroborates the previously postulated two-step degradation process in PADC irradiated with high-energy electrons and 222 nm UV photons. More generally, these results underline the importance of considering the role of low energy secondary electrons in the deterioration of high-sensitivity energetic particle detectors.