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Archita Patnaik
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Archita Patnaik
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Archita Patnaik
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Patnaik, A.
Patnaik, Archita
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6 results
Now showing 1 - 6 of 6
- PublicationEffect of energetic charged particles on laser ablated thin film of poly(phenylene sulfide)(01-06-1998)
;Das, A. ;Sivakumar, N. ;Joseph, M. ;Dhara, S.The effect of energy charged particles in the enhancement of conductivity laser ablated poly(phenylene sulfide) (PPS) is described. Based on the results, it is shown that the FTIR spectrum of the as-deposited film showed characteristic vibrational frequencies at 1560 and 1470 cm-1, these being attributed to aromatic structural vibrations, 1090 cm-1 to thioether linkage and 1008 cm-1 to p-aromatic substitution. XPS analysis of the as-deposited thin films showed formation of oxygen free PPS. The integrated area under the peaks corresponding to C1s and S2p profiles with proper sensitive factors for the as-deposited film amounted to the original stoichiometry of pristine PPS having C:S as 6:1. - PublicationN+ion-target interactions in PPO polymer: A structural characterization(03-01-1999)
;Das, A. ;Dhara, S.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. - PublicationN+ beam induced nano-cluster formation in poly(2,6-dimethyl phenylene oxide) thin films(01-01-1999)
;Das, A. ;Ghosh, G. ;Dhara, S.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. - PublicationDeposition and characterization of laser ablated poly(p-phenylene sulfide) thin films(01-01-1998)
;Das, A. ;Bera, S. ;Joseph, M. ;Sivakumar, N.Thin films of poly(p-phenylene sulfide) [PPS], were deposited by pulsed laser deposition with a doubled Nd: YAG laser (λ = 532 nm) on Si (100) and quartz substrates at temperatures above and below the glass transition temperature (T g ) of the polymer. SEM micrographs of the films showed a decrease of particulate size with increasing substrate temperature. An absorption band edge at 3.4 eV in the UV-VIS spectrum of the deposited film indicated that they were polymeric as well as insulating. FTIR spectra of films deposited at various substrate temperatures mimicked all characteristic vibrational frequencies observed in pristine bulk samples. Low-angle X-ray diffraction patterns and FTIR spectral analysis of the deposited PPS films confirmed that the crystallinity was enhanced when the substrate temperature during deposition exceeded T g . X-ray photoelectron spectroscopic (XPS) investigations of the C 1s spectra of the as-deposited film on Si (100) revealed oxidation of the surface with the formation of sulfone, sulfoxide, C-O and C=O. Ar + ion sputtering with a 4 keV beam at 1 μA beam current removed ∼ 2 nm of the surface film and completely eliminated the sulfone peak from the XPS spectra, retaining a very negligible oxide component. © 1998 Elsevier Science B.V. All rights reserved. - PublicationElectron transport across fractal-like nanocrystalline clusters in N+ ion-beam induced poly(phenylene oxide)(15-05-2001)
;Das, A. ;Dhara, S.The N+ ion-beam induced evolution of a ∼50 nm PPO polymer layer was studied with respect to its chemical and electronic structures along with its fractal geometry. The implanted layer resembled the α-C:H structure with a network consisting of independent clusters of sp2 bonded carbon atoms and an sp3 carbon configuration with H bonded to it. The microcrystalline clusters were determined to be fused hexagonal and polynuclear aromatic rings in a graphitelike phase. The fluence dependent conductivity was found to be associated with a fractal exponent 2 over the fluence range along with a backbone fractal exponent of 3. Electron transport from temperature dependent conductivity measurements in the temperature range 80-280 K was explained in terms of trap controlled hopping of charge carriers between localized states in a defect band in the mobility gap. - PublicationPhysical and chemical implications of 100 keV H+ implantation of laser ablated PPS thin films(01-01-1998)
;Das, A. ;Bera, S. ;Dhara, S.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.