The effects of high electronic energy loss on the chemical modification of polyimide

Abstract

In order to observe the role of electronic energy loss (d E/d X) e on chemical modification of polyimide (PI), the multi-layer stacks (corresponding to different d E/d X) were irradiated by different swift heavy ions (1.37 GeV Ar 40, 1.98 GeV Kr 84, 1.755 GeV Xe 136 and 2.636 GeV U 238) under vacuum and room temperature. The chemical changes of modified PI films were studied by Fourier transform infrared (FTIR) and ultraviolet/visible (UV/Vis) absorption spectroscopy. The degradation of PI was investigated in the fluence range from 1×10 10 to 5.5×10 12 ions/cm 2 and different electronic energy loss from 0.77 to 11.5 keV/nm. The FTIR results show the absorbance of the typical function group decrease exponentially as a function of fluence. The alkyne end group was found after irradiation and its formation radii were 5.6 and 5.9 nm corresponding to 8.8 and 11.5 keV/nm Xe irradiation respectively. UV/Vis analysis indicates the radiation induced absorbance change follows a linear relation as function of fluence corresponding to various ion and the production efficiency of the chromophores depends strongly on the electronic energy loss (d E/d X) e with a power relation.