S. Asad Ali¹,  Rajesh Kumar², Ameer Azam¹,  S. A. H. Naqvi¹, U. De³ and Rajendra Prasad^1,4

¹Department of Applied Physics, Z. H. College of Engineering & Technology, Aligarh     Muslim University, Aligarh-202002, India.
²University School of Basic & Applied Sciences, Guru Gobind Singh Indraprastha University, Delhi-110403
³Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata -700064, India
⁴Vivekananda College of Technology and Management Aligarh-202002

           Passage of swift heavy ions in polymeric material produces a lattice deformation which may be in the form of latent tracks or may vanish by self-annealing in time. The availability of heavy ion beams from accelerators has brought new impetus to the field of ion beam modification in the electrical, chemical and optical properties of polymeric materials which depends on the ion beam parameters and the material itself. In the present work characterization of the optical, chemical and structural modifications in PEO-salt complex induced by  95 MeV O⁶⁺ ions was carried out through UV-Visible spectroscopy, Fourier Transform Infra Red spectroscopy (FTIR) and X-Ray Diffraction (XRD).    Solution-cast films each of total mass 3g of poly-(ethylene-oxide) PEO (BDH, England) and of average molecular weight 600 Kg/mol complexed with NH₄ClO₄ (Fluka AG, 99.5% purity) were prepared in salt concentration of 19%.  Pure PEO is non-conducting while its complex PEO_(1-x) (NH₄ClO₄)_x with weight fraction  x = 19% is an ion conducting polymer. Polymer samples  of PEO-salt complex with 19% salt were exposed  to 95 MeV oxygen ion beam at  15 UD Pelletron accelerator at Inter University Accelerator Centre, New Delhi, India to the fluences of 10¹⁰,10¹¹, 10¹², and 10¹³ ions/cm².

         In UV-Visible spectra a shift in the optical absorption edge towards the red end of the spectrum was observed with the increase in ion fluence. The optical band gap (E_g), calculated from the absorption edge of the UV-Vis spectra of these films in 200-800 nm region varied from 2.68 eV to 1.44 eV for virgin and irradiated samples. The cluster size varied in a range of 164 to 567 carbon atoms per cluster. In FTIR spectra, modification in terms of breaking of the bonds and formation of the lateral chemical bonds induced by heavy ion irradiation is observed. X-ray diffractogram study shows that degree of crystallinity is decreased and shows decreasing trend with the increase in fluence of SHI irradiation.