Damage distribution along heavy ion tracks in polymers

Recently we have confirmed the scission of ether bonds occurred in the almost same efficiency to CO2 gas formation along ion tracks in CR-39. This means that the part between two carbonate ester bonds in each repeat unit can be segmented into at least 4 gaseous molecules including CO2. We think that this kind of segmentation should be a key phenomenon to produce latent tracks in CR-39. Now, we are trying to construct a quantitative track formation model in it. For this purpose, we have assessed the G values in bisphenol A polycarbonate films with 3 μm thickness for the scission of carbonate ester bonds. Several stacks of PC films were exposed to heavy ions in air. Depth-distributions of damage along each track were obtained using FT-IR spectrometer. The G-values for the loss of C=O bond were 2.1±0.2, 3.1±0.2 and 3.0±0.3 (C=O/100eV) for C, Ar and Fe ions, respectively. (author)