In situ photon-emission spectroscopy and ex situ surface analyses of polymers irradiated with 60 keV Cu- ions

Ion-induced surface modification processes of polystyrene (PS) and high-density polyethylene (HDPE) have been studied by either in situ photon-emission spectroscopy or ex situ surface analyses. Heavy Cu- ions of 60 keV irradiated the polymers at a dose rate of 1 μA/cm2 and ion-induced photon emission was in situ measured in a spectral region of 250-850 nm. Ion-induced chemical reactions of the surface layers were ex situ evaluated by X-ray photoelectron spectroscopy (XPS). Intensity, spectral shape and dose dependence of the photon emission were significantly different between aromatic-containing polymers (PS) and linear polymers (HDPE) in the same irradiation condition. The emission spectrum of HDPE represented a broad band with a maximum at about 595 nm, while that of PS showed a sharp peak around 656 nm. The total emission yield observed for PS was much lower than that of HDPE, and the decay rates of emission intensity for PS were different from that of HDPE in a dose region less than 1014 ions/cm2. The XPS analyses showed chemical change of the surface bonding. These results suggested that ion-induced processes caused hydrogen extraction, crosslinking and bond scission of the matrix