Photoluminescent and thermal behavior of 120 MeV silicon and 84 MeV oxygen ion irradiated PVDC

Photoluminescent, structural and thermal changes induced in polyvinylidenechloride (PVDC) films by irradiation with energetic silicon and oxygen ions have been determined using different techniques viz PL, FTIR, UV-vis, XRD, TGA and AFM. Noticeable photoluminescence was observed in PVDC after irradiation with 84 MeV oxygen ions at fluence 3.2×10¹¹ ions cm⁻², which is attributed to the small carbon cluster formed in the polymer due to irradiation. Quenching and shifting in the position of the PL band towards the longer wavelength side of the spectrum was observed with the increase in ion fluence. UV-vis and FTIR analysis have strongly corroborated the results of PL spectroscopy. X-ray diffractograms and TGA curves show decrease in crystallinity and weight loss, respectively, of PVDC films after irradiation. The strong correlation between the behaviors of different properties were analyzed and discussed in the present paper.     

Carbon (70 MeV) and copper (120 MeV) ions irradiation effects in Makrofol-N

Makrofol-N polycarbonate was irradiated with carbon (70 MeV) and copper (120 MeV) ions to analyze the induced effects with respect to optical and structural properties. In the present investigation, the fluence for carbon and copper beams was kept in the range of 1×10¹¹– 1×10¹³ ions/cm² to study the swift heavy ion induced modifications. UV–VIS, FTIR and XRD techniques were utilized to study the induced changes. The analysis of UV–VIS absorption studies revealed that the optical energy gap was reduced by 17% on carbon irradiation, whereas the copper beam leads to a decrease of 52% at the highest fluence of 1×10¹³ ions/cm². The band gap can be correlated to the number of carbon atoms, N, in a cluster with a modified Robertson's equation. In copper (120 MeV) ions irradiated polycarbonate, the number of carbon atoms in a cluster was increased from 63 to 269 with the increase of ion fluence from 0 to 1×10¹³ ions/cm², whereas N is raised only up to 91 when the same polymer films were irradiated with carbon (70 MeV) ions under similar conditions. FTIR analysis showed a decrease in almost all characteristic absorption bands under irradiation. The formation of hydroxyl (? OH) and alkene (C?C) groups were observed in Makrofol-N at higher fluence on irradiation with both types of ions, while the formation alkyne end (R? C≡ CH) group was observed only after copper ions irradiation. The radii of the alkyne production of about 3.3 nm were deduced for copper (120 MeV) ions. XRD measurements show a decrease in intensity of the main peak and an increase of the average intermolecular spacing with the increase of ion fluence, which may be attributed to the structural degradation of Makrofol-N on swift ion irradiation.     

Physical and chemical response of polypropylene irradiated with 70 MeV carbon and 150 MeV nickel-ions

Polypropylene films were irradiated with C⁵⁺ (70 MeV) and Ni¹¹⁺ (150 MeV) ions of varying fluence. The ion induced optical, chemical and structural changes were investigated using UV-Vis and Fourier Transform Infrared (FTIR) spectroscopy and X-ray diffractometry (XRD). UV-Vis data showed an increase of optical absorbance and a shift of the absorption edge towards the red end of the spectrum when the ion fluence was increased. This shift may be attributed to the greater degree of conjugation. FTIR analysis revealed the formation of alcoholic and ketonic groups. Significant loss of crystallinity occurred with increasing ion fluence.     

AC electrical properties of proton irradiated EVA films

MeV ions passing through polymeric films modify their electrical, optical and thermal properties and these changes are related to changes in the chemical structure of the polymers. Ethylene vinyl acetate (EVA) films were irradiated with 3 MeV proton beam at different fluences of 10¹³, 10¹⁴ and 10¹⁵ ions/cm². AC electrical properties of pristine and irradiated samples were studied in the frequency range 100 Hz to 100 kHz by means of an LCR meter. There is an exponential increase in conductivity with log frequency and conductivity increases as fluence increases. The dielectric loss/constant is observed to change with the fluence. FTIR spectra reveals significant change in intensities of functional groups at a fluence of 10¹⁵ ions/cm² due to scissioning of polymer chains.     

Effect of 50 MeV Li+3 and 80 MeV C+5 ions’ beam irradiation on the optical,structural, chemical and surface topographic properties of PMMA films*

The self-standing films of polymethyl methacrylate (PMMA) were irradiated under vacuum with 50?MeV lithium (Li³⁺) and 80?MeV carbon (C⁵⁺) ions to the fluences of 3?×?10¹⁴, 1?×?10¹⁵, 1?×?10¹⁶ and 1?×?10¹⁷ ions µm^?2. The pristine and irradiated samples of PMMA films were studied by using ultraviolet–visible (UV–Vis) spectrophotometry, Fourier transform infrared, X-ray diffractrometer and atomic force microscopy. With increasing ion fluence of swift heavy ion (SHI), PMMA suffers degradation, UV–Vis spectra show a shift in the absorption band from the UV towards visible, attributing the formation of the modified system of bonds. E_g and E_a decrease with increasing ion fluence. The size of crystallite and crystallinity percentage decreases with increasing ion fluence. With SHI irradiation, the intensity of IR bands and characteristic bands of different functional groups are found to shift drastically. The change in (E_g) and (N) in carbon cluster is calculated. Shifting of the absorption band from the UV towards visible along with optical activity and as a result of irradiation, some defects are created in the polymer causing the formation of conjugated bonds and carbon clusters in the polymer, which in turn lead to the modification in optical properties that could be useful in the fabrication of optoelectronic devices, gas sensing, electromagnetic shielding and drug delivery.     

Spectroscopic studies of copper and carbon ion irradiated polypropylene

The samples of polypropylene (PP) have been irradiated with 120 MeV ⁶⁴Cu⁹⁺ and 70 MeV ¹²C⁵⁺ ion beams, with the fluence ranging from 1 × 10¹³ to 1 × 10¹¹ ions/-cm⁻². UV-VIS and FTIR techniques have been used to study the chemical and optical properties of these irradiated polymers. UV spectra revealed that the optical-gap energy decreases by 54 % with copper ion irradiation at the fluence of 1 × 10¹³ ions/cm², whereas at the same fluence, carbon beam decreases the optical-gap energy by 20%. FTIR analysis of ion irradiated samples revealed the presence of -OH, C = O and C = C bonds. Alkyne formation has been observed only in the case of copper ion irradiation.      

Optical and Structural Modifications in Heavy Ion Irradiated Polystyrene

Samples of polystyrene (PS) have been irradiated with ⁶⁴Cu (50 and 120 MeV) and ¹²C (70 MeV) ion beams (fluence=10¹¹ to 10¹³ ions cm^?2) in order to study the induced modifications using UV‐VIS and FTIR spectroscopy. UV spectra of irradiated samples reveal that the optical band gap decreases from 4.36 to 1.46 eV in PS. The decrease in optical band gap is more pronounced with the Cu‐ion beam due to high electronic energy loss as compared to the C ion beam. The effect of low energy (50 MeV) Cu ions on the optical properties of PS is larger than that due to high energy (120 MeV) Cu ions. The correlation between the optical band gap and the number of six member carbon rings inside the largest carbon clusters embedded in the network of polystyrene is discussed. FTIR spectra reveal the formation of hydroxyl, alkene, and alkyne groups in the Cu‐ion irradiated PS. Changes in the intensity of the absorption bands on irradiation with C‐ion relative to pristine samples have also been observed and are discussed.     

High-energy ion induced physical and surface modifications in antimony sulphide thin films

Sb₂S₃ thin films prepared by electrodeposition on indium tin oxide coated glass substrate were irradiated with 150 MeV Ni¹¹⁺ ions for various fluence in the range of 10¹¹–10¹³ ions/cm². The modifications in the structure, surface morphology and optical properties have been studied as a function of ion fluence. X-ray diffraction (XRD) analysis indicates a shift in the (2 4 0) peak position towards lower diffraction angle and a decrease in grain size with increase in ion fluence. Presence of microcracks due to irradiation induced grain splitting effect has been observed from the SEM micrograph at higher ion fluence. The optical absorbance spectrum revealed a shift in the fundamental absorption edge and the band gap energy increased from a value of 1.63 eV for as-deposited films to 1.80 eV for the films irradiated with 10¹³ ions/cm².     

Optical behaviour of swift heavy ions irradiated poly(vinyl alcohol) films

Polyvinyl alcohol films were irradiated to 90 MeV O ⁶⁺ and 150 MeV Si ¹⁴⁺ ions at fluence ranging from 10¹⁰ to 10¹² ions/cm². The observed changes in optical energy gap of this polymer have been investigated and results are tried to be explained in terms of energy transferred by the incident ions. It has been noticed that the value of optical energy gap decreases with increasing energy loss during the ion–polymer interaction process.     

Effect of swift heavy ion irradiation on photoluminescence properties of ZnO/PMMA nanocomposite films

We report a study on the SHI induced modifications on structural and optical properties of ZnO/PMMA nanocomposite films. The ZnO nanoparticles were synthesized by the chemical route using 2-mercaptoethanol as a capping agent. The structure of ZnO nanoparticles was confirmed by XRD, SEM and TEM. These ZnO nanoparticles were dispersed in the PMMA matrix to form ZnO/PMMA nanocomposite films by the solution cast method. These ZnO/PMMA nanocomposite films were then irradiated by swift heavy ion irradiation (Ni⁸⁺ ion beam, 100 MeV) at a fluence of 1×10¹¹ ions/cm². The nanocomposite films were then characterized by XRD, UV-vis absorption spectroscopy and photoluminescence spectroscopy. As revealed from the absorption spectra, absorption edge is not changed by the irradiation but the optical absorption is increased. Enhanced green luminescence at about 527 nm and a less intense blue emission peak around 460 nm were observed after irradiation with respect to the pristine ZnO/PMMA nanocomposite film.     

Dielectric response of makrofol-KG polycarbonate irradiated with 145 MeV Ne6+ and 100 MeV Si8+ ions

The passage of heavy ions in a track detector polymeric material produces lattice deformations. These deformations may be in the form of latent tracks or may vanish by self annealing in time. Heavy ion irradiation produces modifications in polymers in their relevant electrical, chemical and optical properties in the form of rearrangement of bonding, cross-linking, chain scission, formation of carbon rich clusters and changes in dielectric properties etc. Modification depends on the ion, its energy and fluence and the polymeric material. In the present work, a study of the dielectric response of pristine and heavy ion irradiated Makrofol-KG polycarbonate is carried out. 40 μm thick Makrofol-KG polycarbonate films were irradiated to various fluences with Si⁸⁺ ions of 100 MeV energy from Pelletron at Inter University Accelerator Centre (IUAC), New Delhi and Ne⁶⁺ ions of 145 MeV from Variable Energy Cyclotron Centre, Kolkata. On irradiation with heavy ions dielectric constant (ɛ′) decreases with frequency where ɛ′ increases with fluence for both the ions. Variation of loss factor (tan δ) with frequency for pristine and irradiated with Si ions reveals that tan δ increases as the frequency increases. Tan δ also increases with fluence. While Ne irradiated samples tan δ shows slight variation with frequency as well as with fluence. Tan δ has positive values indicating the dominance of inductive behavior.      

Swift heavy ion induced modifications in cobalt doped ZnO thin films: Structural and optical studies

Modifications in the structural and optical properties of 100 MeV Ni⁷⁺ ions irradiated cobalt doped ZnO thin films (Zn_1−xCo_xO, x = 0.05) prepared by sol-gel route were studied. The films irradiated with a fluence of 1 × 10¹³ ions/cm² were single phase and show improved crystalline structure with preferred C-axis orientation as revealed from XRD analysis. Effects of irradiation on bond structure of thin films were studied by FTIR spectroscopy. The spectrum shows no change in bonding structure of Zn-O after irradiation. Improved quality of films is further supported by FTIR studies. Optical properties of the pristine and irradiated samples have been determined by using UV-vis spectroscopic technique. Optical absorption spectra show an appreciable red shift in the band gap of irradiated Zn_1−xCo_xO thin film due to sp-d interaction between Co²⁺ ions and ZnO band electrons. Transmission spectra show absorption band edges at 1.8 eV, 2.05 eV and 2.18 eV corresponding to d-d transition of Co²⁺ ions in tetrahedral field of ZnO. The AFM study shows a slight increase in grain size and surface roughness of the thin films after irradiation.     

Copper (50 MeV) and Oxygen (84 MeV) Ion Irradiation Probed Thermal,Structural and Optical Behavior of Polyethylene Terephthalate

Polyethylene terephthalate (PET) films of 50?μm thickness were exposed to swift-heavy 50?MeV copper and 84?MeV oxygen ions, with fluence varying from 1?×?10¹¹ to 1?×?10¹³ ions cm^?2. Differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) and UV-visible spectroscopic techniques were used to characterize the irradiated samples. The XRD and DSC analysis indicated the loss of crystallinity during/after the irradiation. The FTIR spectra revealed the formation of alkyne end groups, C═C groups and structural deformation with increase of ion fluence. Considerable reduction in the value of the optical bandgap was inferred from the study of the UV-visible absorption curves.     

Induced Electronic and Thermal Effects of 86 MeV Nickel Ions in Bisphenol-A Polycarbonate

Bisphenol-A polycarbonate films were irradiated with 86 MeV swift heavy nickel ions at varying fluences, ranging from 1 × 10¹¹ to 1 × 10¹³ ions cm^?2, under vacuum at room temperature, to analyze the induced electrical and thermal modifications. AC conductivity measurements and UV-visible spectroscopy, Fourier transform infra-red (FTIR) spectroscopy, thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) techniques were applied to analyze the changes. A significant, exponential increase in conductivity at higher frequency was observed with the increase of nickel ion fluence. UV-visible analysis corroborated the results of the AC conductivity measurement, revealing the increase in size of the carbon clusters embedded in the polymer network, with the increase of heavy ion fluence. FTIR analysis revealed the formation of alkene and alkyne end groups at higher doses, which further supported the suggestion that the variation in electrical properties induced by the ion irradiation of the polymer was due to development of a carbonaceous phase inside the polymer due to the irradiation. Thermal analysis, i.e., TGA and DSC patterns, showed that chain-scission was the leading phenomena in the heavy ion-irradiated polycarbonate samples, resulting in degradation of their thermal stability.     

Structural,optical and electrical properties of 60 MeV C5+ ion-irradiated poly(3-methylthiophene) films

The structural, optical and electrical properties of 60 MeV C⁵⁺ ion-irradiated poly(3-methylthiophene) (P3MT) synthesized by the chemical oxidation polymerization method have been studied. The P3MT powder was dissolved in chloroform (CHCl₃), and thin films of thickness 2 μm were prepared on glass and Si substrates. The polymerization was confirmed by the FTIR spectrum. Then films were irradiated by 60 MeV C⁵⁺ ions at different fluences. FTIR spectra show methyl group evolution after irradiation. The optical band gap decreases slightly after irradiation and the DC conductivity increases by about one order of magnitude after irradiation at the highest fluence. The role of S _e has also been discussed when compared with 60 MeV Si⁵⁺ ion irradiation of P3MT. The morphological changes are observed using SEM.     

Studies on structural,optical and cluster size of poly(m-toluidine)–polyvinyl chloride blends

Poly(m-toluidine) (PmT), a derivative of polyaniline, has been prepared by chemical oxidation polymerization method. The synthesized PmT powder is blended with plasticized polyvinyl chloride (PVC) to achieve 20 μm thick self-supported films. These films were irradiated with 60 MeV Si⁵⁺ ions at three different fluences whose S _e (electronic energy loss) value is found to be 1.988×10³ KeV/μ m, an order of magnitude larger than 60 MeV C⁵⁺ (2.958×10² KeV/μ m). Fourier transform infrared (FTIR), X-ray diffraction (XRD) and ultraviolet-visible (UV) absorption studies of pre- and post-irradiated films of PmT–PVC blends were carried out to study the heavy ion irradiation effects on these polymer blends. An overall change in the structure of the polymer blend has been observed from FTIR studies. UV-visible spectra show a decrease in the optical band gap (E _g) and an increase in cluster size with increasing fluence. An effort is made to compare these results with our earlier studies. We found that the variation in S _e plays an important role in the structural and optical properties of PmT–PVC blends.     

Effect of nitrogen ions on the structural,optical, and thermal properties of polyvinyl alcohol/starch blend

This work examines the properties of polyvinyl alcohol (PVA)/starch film containing glycerol as a plasticizer under exposure to different nitrogen ion fluence. The prepared PVA/starch blend was irradiated with ion fluence from 3 × 10¹⁷ to 12 × 10¹⁷ ions.cm⁻². From FTIR, the ion beam irradiation attack and weakens the C–H bond in PVA/starch blend. From XRD findings, the crystallite size of the blend decreased at 3 × 10¹⁷ ions/cm² while it increased at higher fluence up to 9 × 10¹⁷ ions/cm². This indicates the degradation of the blend at low ion fluence compared to crosslinking at high ion fluence. Also, the optical bandgap of the blend was decreased with an increase in ion fluence. Furthermore, the effect of N⁺ ions on some optical dispersion parameters is studied. The thermal stability of the PVA/starch blend shows a decrease in thermal stability upon irradiation with 3 × 10¹⁷ ions/cm² compared to higher thermal stability at higher doses up to 9 × 10¹⁷ ions/cm².     

Modification of polyethylene terephthalate by proton irradiation

Polyethylene terephthalate (PET) films were irradiated with 3 MeV proton beams at different fluences. The microhardness, electrical, thermal and structural studies were carried out using microhardness tester, LCR meter, thermogravimetric analysis (TGA) and FTIR spectroscopy. Vickers' hardness has been observed to increase with the fluence. The true bulk hardness of the film was obtained at loads greater than 400 mN. The AC electrical conductivity is practically unaffected by irradiation up to a frequency of 10 kHz, but it is found to increase exponentially at a frequency of 300 kHz. The loss factor and dielectric constant are observed to change appreciably with the fluence. It is observed that there is no significant change in the stability of the polymer up to the fluence of 10¹⁴ ions cm^?2 as revealed by TGA and FTIR spectroscopy.     

Surface modifications of PADC polymeric material by ion beam bombardment for high technology applications

Surface modification of Poly (allyl diglycol carbonate) (PADC) is induced by 150 keV Ag ions of different fluences. The pristine as well as bombarded samples were investigated by UV–Vis spectroscopy, Fourier transform-infrared analysis (FTIR) and micro-hardness tester. The variations of wettability and surface free energy were determined by the contact angle measurements. The obtained results showed that ion beam bombardment induced increase in the absorption spectra of the UV–Vis with increase of ion fluence as well. The direct and indirect optical band gap decreased from 4.2 to 3.6 eV for pristine sample to 3.2 and 2.5 eV for those bombarded with Ag ion beam at the highest fluence, respectively. Changes in chemical properties were observed by Fourier transform infrared spectroscopy. Increase in the wettability, surface free energy and work of adhesion with increase the ion fluence were observed. Ion bombardment inducing increasing in a micro-hardness surface due to the high carbon surface concentration and cross-linking effects in the polymeric chains. The bombarded PADC surfaces may find special applications to the field of the micro-electronic devices and printing process.     

Ion beam induced modifications in nitroso substituted polyaniline: Spectral and electrical studies

The effects of ion beam irradiation on optical, chemical and electrical properties of nitroso substituted polyaniline, polynitrosoaniline (N-PANI) have been investigated. N-PANI was irradiated with 100 MeV ²⁸Si ions at different ion-fluences. The pristine and irradiated polymer samples were characterized by FT-IR, UV–visible spectroscopic techniques. The electrical conductivity studies were conducted on polymer samples. A significant change in optical band gap and room temperature electrical conductivity was observed in polymer samples after irradiation. The solubility of the polymer samples has also been tested in 1-methyl-2-pyrrolidone (NMP).