Archita Patnaik

N+ ion beam induced effects on the spin coated amorphous poly(2,6-dimethyl phenylene oxide) (PPO) films in terms of chemical structure and electronic and vibrational properties were investigated using Fourier Transform Infrared spectroscopy (FTIR) and Ultraviolet-Visible (UV-VIS) spectroscopy. Both techniques revealed that the stability of PPO was very weak towards 100 keV N+ ions revealing the threshold fluence to be 1014 ions/cm2 for fragmentation of the polymer. FTIR analysis showed disappearance of all characteristic IR bands at a total fluence of 1014 ions/cm2 except for the band CC at 1608 cm-1 which was found to shift to a lower wave number along with an enhancement in the full width half maximum (FWHM) value with increasing fluence. A new bond appeared due to oxidation as a shoulder at 1680 cm-1 in FTIR spectra indicating the presence of CO type bond as a result of N+ implantation on PPO films. The optical band gap (Eg) deduced from absorption spectra, was observed to decrease from 4.4 to 0.5 eV with fluence. The implantation induced carbonaceous clusters, determined using Robertson's formula for the optical band gap, were found to consist of ~160 fused hexagonal aromatic rings at the maximum energy fluence. An enhanced absorption coefficient as a function of fluence indicated incorporation of either much larger concentration of charge carriers or their mobility than that of the pristine sample. Calculated band tail width from Urbach band tail region for the implanted samples pointed the band edge sharpness to be strongly dependent on fluence indicating an increased disorder with increasing fluence. © 1999 Elsevier Science B.V.

We report the energetic N+ (100 keV) implantation effect on the spin cast film of poly(2,6-dimethyl phenylene oxide) [PPO] and formation of ion beam induced crystalline nano-clusters, for the first time. Evidence for the formation of highly oriented clusters of ∼ 22 nm size is obtained from grazing incidence XRD (GIXRD) analysis of the implanted PPO films with a fluence of 6 × 1016 ions/cm2 whereas the as-deposited film is found amorphous. All the characteristic Raman peaks of PPO film disappears and subsequently a broad peak at 1500 cm-1 in the FT-Raman spectrum appears implying the presence of graphite like carbon (GLC) in the implanted polymer. DC conductivity behaviour in the implanted sample has shown the dominant role of three dimensional (3-D) variable range hopping (VRH) mechanism in the temperature range of 303-500 K. The role of clusters is discussed in analysing the current transport mechanism in the implanted polymer. © 1999 Elsevier Science B.V. All rights reserved.

Structural and chemical investigation for the laser ablated Poly (Phenylene Sulfide) (PPS) films upon 100 keV H+ implantation is reported here for the first time. PPS thin films were fabricated by laser ablation with a Nd: YAG laser as a source of visible photons (532 nm). The laser ablated thin films showed strong polymer breakdown resistance upto a total fluence of 1015 ions/cm2. Bulk properties of the as-deposited and the implanted samples were investigated using FTIR and UV-VIS spectroscopy. Drastic reduction in the intensity of all characteristic vibrational frequencies in the FTIR spectrum at higher doses revealed the transformation of the polymer to a conjugated carbonaceous material. UV-VIS studies showed a positive shift in the absorption edge value for the as-deposited polymer towards higher wavelengths and destruction of phenyl ring due to the H+ bombardment. X-ray Photoelectron Spectroscopic (XPS) investigation indicated the sulfur depletion as a prominent phenomenon whereas carbon content remained almost the same. XPS studies of the implanted sample also revealed a minor change in the oxidized species of carbon and more prominent change in oxidized species of sulfur which were present in the as-deposited samples. A peak at 283.4 eV attributed to 'surface reconstruction' in the XPS analysis for the as-deposited PPS film disappeared after proton implantation. © 1998 Elsevier Science B.V.