Electronic energy loss effects in polystyrene irradiated with high energy argon ions

Stacked polystyrene films of about 53 mum in thickness were irradiated with 1.4GeV argon ions at room temperature and in vacuum. The radiation induced chemical changes of each film were studied by the Fourier-transform infrared (FT-IR) and ultraviolet/visible (UV/VIS) spectroscopies. It is found that the material is seriously degraded after irradiation and the chemical modifications depend strongly on electronic energy loss. Significant degradation of the material occurs above about 0.77keV/nm at the dose of 5.5 x 10(12) ions/cm(2), corresponding to an energy deposition of 6.4MGy. The main chains of PS as well as the phenyl ring are destroyed in the track core simultaneously. Damage cross sections of about 29nm(2) are found for phenyl ring and the -CH2- group. Alkynes are produced above an energy loss of 0.77keV/nm.