INTERNATIONAL JOURNAL OF APPLIED ENGINEERING RESEARCH, DINDIGUL Volume 2, No 2, 2011 © Copyright 2010 All rights reserved Integrated Publishing Association RESEARCH ARTICLE ISSN - 0976-4259 419 Study of chemical, optical and structural properties of 120 MeV Ni 11+ ions beam irradiated poly (ethylene terephthalate) film Vijay Kumar 1 , Sonkawade R G 2 , Yasir Ali 1 , Dhaliwal A.S 1 1- Department of Physics, Sant Longowal Institute of Engineering and Technology Longowal Distt. Sangrur, Punjab-148106, India 2- School of Physical Sciences, Babasaheb Bhimrao Ambedkar University (A Central University) Rae Bareli Road, Vidya Vihar, Lucknow-226025, India rgs22@rediffmail.com ABSTRACT We study the effect of 120 MeV Ni 11+ ions beam irradiations at various fluence ranging from 3x10 10 to 3x10 12 ions/cm 2 on the optical, chemical, and structural properties of poly (ethylene terephthalate) (PET) polymer films. Irradiation on polymeric materials generally leads to a formation of free radicals and ions, with secondary effects such as cross-linking as well as chain scission. To confirm these effects various characterization techniques have been explored viz. UV-Vis, X-ray diffraction (XRD), and Fourier Transforms Infrared (FTIR) spectroscopy. Substantial decrease in optical band gap is observed with the increase of the ion fluence. In the FTIR spectra nearly all bands were decreases due the degradation of the molecular structure after irradiation. XRD measurements show the decrease of the main XRD peak intensity, reflects the loss of crystallinity after irradiation. Moreover, crystallinity and crystallite size changes with increasing fluence. The results will be discussed on the basis of ion beam induced modifications. Keywords: PET, Heavy ion irradiation, UV-Vis, XRD, FTIR Nomenclature PET = Poly (ethylene terephthalate) XRD = X-ray diffraction FTIR = Fourier Transforms Infrared S e = Electronic energy loss S n = Nuclear energy loss L = Particle size b = Full width at half maxima X c % = Percentage of crystallinity LET = Linear energy transfer N = Number of carbon atoms 1. Introduction As advanced technologies keep developing every day, there is a constant need for novel materials with special properties and/or combinations of unique properties. In pursuit of modified and improved properties of polymers, recent research trends reflect a sheer