Stacked polyimide (PI) films of about 25 μm in thickness were irradiated with 1.755 GeV xenon ions under vacuum at room temperature. The chemical changes of modified PI films were studied by Fourier transform infrared (FTIR) and ultraviolet/visible (UV/Vis) absorption spectroscopy. The FTIR results show that the absorbance of the typical function groups decreases exponentially as a function of fluence. Under 8.8 keV/nm (minimum) and 11.5 keV/nm (maximum) electronic energy loss of 136Xe irradiation

the mean degradation radius of all function groups in PI is 3.6 and 4.1 nm

respectively. The alkyne end group was found after irradiation and its formation radius was 5.6 nm and 5.9 nm corresponding to 8.8 keV/nm and 11.5 keV/nm

respectively. The UV/Vis analysis indicates the radiation induced absorbance change follows a linear relation with fluence

and the production efficiency of chromospheres depends strongly on the electronic energy loss ( d E / d X ) e.