The thermal-spike model description of the ion-irradiated polyimide

To describe the role of electronic energy loss (dE/dX)(e) for chemical modification of polyimide (PI), multi-layer stacks (corresponding to different dE/dX) were irradiated by different swift heavy ions (1.158 GeV Fe-56 and 1.755 GeV Xe-136) under vacuum and at room temperature. Chemical changes of modified PI films were studied by Fourier transform infrared (FTIR) spectroscopy. The chain disruption rate of PI was investigated in the fluence range from 1 x 10(11) to 6 x 10(12) ionS/cm(2) and a wider energy stopping power range (2.2-5.1 keV/nm for Fe-56 ions and 8.6-11.5 keV/ nm for Xe-136 ions). Alkyne formation was observed over the electronic energy loss range of interest. By applying the saturated track model assumption (the damage process only occur in a cylinder of area a), the mean degradation and alkyne formation radii in tracks were induced for Fe and Xe ion irradiation, respectively. The results were validated by the thermal-spike model. The analysis of the irradiated PI films shows that the predictions of the thermal-spike model of Szenes are in qualitative agreement with the curve shape of experimental results. (C) 2003 Elsevier B.V. All rights reserved.