EPR and UV spectroscopic investigations of sucrose irradiated with heavy-ion particles

Crystalline sucrose irradiated with C and Si ions is investigated with EPR and UV spectroscopy. Samples are treated at different doses of radiation in the region 20–300 Gy and linear energy transfer (LET) values of 39.6, 49 and 58 keV μm^?1 for C ions and 60 keV μm^?1 for Si ions. All samples exhibit identical EPR spectra due to radiation-induced stable sucrose radicals. At given constant LET the EPR signal responses are linear to the absorbed doses of Si and C ions. Water solutions of irradiated sucrose exhibit UV absorption maximum at 267 nm due to the product of radical recombination. The intensity of this band is stronger at irradiation with Si than with C ions. UV absorption is more sensitive to heavy-ion species irradiation than the EPR signals.     

EPR of gamma irradiated solid sucrose and UV spectra of its solution. An attempt for calibration of solid state/EPR dosimetry

A simple new approach for independent calibration of solid state/EPR (SS/EPR) dosimetry system is reported. It is based on the fact that: (i) gamma-irradiation of solid sucrose (sugar) induces stable EPR detectable free radicals accompanied by UV detectable brown colour stable in the solid state and in solution; (ii) both the EPR intensity of gamma-irradiated solid sucrose and its solution UV absorbance linearly depend on the absorbed dose high energy radiation and may be independently used for dosimetric purpose; (iii) UV spectrometers are calibrated. The correlation between EPR response and absorbed dose radiation of solid sucrose and UV absorption of its solutions is used in the present communication for calibration purpose. The procedure of sucrose extraction from sucrose-paraffin dosimeters is described. The calibration procedure may be applied to any other (alanine, self-calibrated, etc.) SS/EPR dosimeters, simultaneously irradiated with sucrose.     

EPR Investigation of Radical-Production Cross Sections for Sucrose and L-alanine Irradiated with X-rays and Heavy-ions

Using electron paramagnetic resonance (EPR), we investigated stable radical-production cross sections (σ) of sucrose and L-alanine radicals produced by heavy-ion irradiations with various linear energy transfers (LET). The heavy-ion irradiation results were compared with those of X-ray irradiation at the same dose. The EPR signal areas for the two compounds showed a linear relation with the absorbed dose, as well as a logarithmic correlation with the LET. Further analysis was carried out for the radical-production cross section, which showed that stable radicals of the two compounds were produced through collisions of several particles with a single molecule. The relative σ value of sucrose for C ion irradiation was (1.29 ± 0.64) × 10⁻¹² μm². The σ value of alanine for C ion irradiation was (6.83 ± 0.42) × 10⁻¹³ μm². Considering the structural molecular sizes of sucrose and alanine, the σ values are similar. In addition, a comparison of the EPR results for the C ions and X-rays at 50 Gy dose was made. Sucrose spin concentrations produced by C ions at the LET value of 13.1 keV/μm and X-rays were similar unlike alanine. Thus, the noble EPR results with X-ray and heavy-ion irradiations imply that sucrose can be useful as a radiation indicator.     

Composition,temperature and radiation induced changes in gamma irradiated AAAMPS copolymer

Effect of composition, temperature and radiation dose in gamma irradiated acrylamide-2-acrylamido-2-methyl propane sulphonic acid (AA) copolymer has been investigated by electron spin resonance (ESR) and fourier transform infrared (FTIR) techniques. ESR spectra of gamma irradiated AA copolymer have been recorded under different conditions. The observed ESR spectra are analysed by computer simulation techniques, to separate the constituent component spectra. Magnetic parameters employed to simulate the component spectra enabled the identification of corresponding free radicals. The AA copolymer with low acrylamide content composed of macroradicals of the type ?CH₂?CH?CH₂? and methyl radicals (CH₃) whereas the copolymer with high acryl amide content possess methyl radicals and radicals of the type ?CH₂?C(CONH₂)?CH₂?/CH₃?C?CH₃. Reasons for the variation in the formation of free radicals have been explained. The observed changes in ESR spectra of irradiated AA copolymer at higher temperatures are thought to be due to the recombination of free radicals. Formation of free radicals found to be enhanced with the increase in dose of irradiation. FTIR spectra of pure and irradiated copolymers have also confirmed the previous results.     

EPR dosimeter material properties of potassium tartrate hemihydrate

The ability of potassium tartrate hemihydrate as a radiation sensitive material for electron paramagnetic resonance (EPR) dosimetry was investigated. The samples were subjected to different doses, in the range of 1–9 Gy of ⁶⁰Co gamma rays at room temperature. The EPR spectra were investigated through variation of signal intensity with respect to absorbed dose, magnetic field modulation amplitude, microwave power and time stability. The results indicate that the sensitivity of potassium tartrate hemihydrate is about 30% higher than that of alanine. However, the EPR signal is timely less stable within the first two weeks after irradiation.     

Modifications induced by gamma irradiation upon structural,optical and chemical properties of polyamide nylon-6,6 polymer

The effects of gamma rays were studied on the optical, structural and chemical properties of the PA-66 polymer samples. The polymer samples obtained from Goodfellow (Cambridge, UK) were irradiated with gamma rays at various doses ranging from 100 to 1250 kGy. The pristine and gamma rays irradiated samples were characterized by UV–visible (UV–VIS) spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. UV–VIS shows a shift in absorption toward the visible region for irradiated samples and a decrease in band gap energy (E_g). The XRD analyses show an increase in the crystalline nature of the polymer at higher doses as a result of significant decrease in the peak width of XRD patterns. The FTIR spectra show decrease in intensity and shift of various bands with increase in gamma dose.     

Effect of radiation dose with low dose rate on degradation of propylene–ethylene copolymer

Medical grade propylene–ethylene (P–E) copolymer was irradiated by gamma rays. The radicals generated in the irradiated P–E copolymer were identified by using electron spin resonance (ESR) technique and the structural changes in the polymer were monitored with Fourier transform infrared spectroscopy (FTIR). The ESR spectra were analysed with computer simulations. The ESR studies show the formation of macro (～CH₂–?H–CH₂～), peroxy (POO˙), methyl and acyl (R–?=O) radicals and the asymmetric doublet, characteristic of peroxy radicals in the case of the sample irradiated at low dose (1 Mrad) and high doses (30 and 40 Mrad), respectively. The FTIR spectra of irradiated P–E copolymer indicate an increase in the concentration of peroxide groups. The absorption bands of –C=O and –OH groups were increased and the decline in the intensity of –CH₃ group absorption band is reported.     

EPR study of table sugar rod and powder as high dose dosimeters

In order to improve the ease of sample handling, the reproducibility of signal detection and quantification, simple methods of incorporating a homogeneous mixture containing sugar powder (30%) with wax (35%) and rubber (35%) into rods has been adopted. The dose response, the time stability of the free radicals produced in table sugar dosimeters (in both rod and powder form) by gamma radiation and the effect of the temperature during irradiation were studied by EPR (Electron Paramagnetic Resonance). The peak-to-peak height (PPH) measurement of the EPR signal is studied as a function of the absorbed gamma dose in the range 0.1–58 kGy. For the two forms, a linear dependency is found between 0.1 and 26 kGy. At higher doses the EPR signal amplitude continues to grow but non-linear up to 58 kGy. The dependence of temperature during irradiation has been investigated in the temperature range 25–40 °C and the calculated correction coefficients were found (2.7 ± 0.2)% °C^?1 and (1.5 ± 0.3)% °C^?1, respectively, for powder and rod forms. The time stability of the stored sugar samples was investigated for 34 days at room temperature, a rapid decrease of EPR signal was showed immediately after irradiation followed by slowly decrease.     

Interaction of water vapor with gamma-radiation-induced defects in proton conductive polymers

The correlation between protonic conduction and the amount of radiation-induced defects in gamma-ray-irradiated perfluorosulfonic acid (PFSA) polymers (Aciplex-SF-1004^®) has been investigated using a direct-current resistance method, transmission spectroscopy for the ultraviolet (UV) and visible (Vis) wavelength ranges and Fourier transform infrared (FTIR) spectroscopy with the attenuated total refraction (ATR) technique. The proton conductivity of the polymers, which are irradiated with a dose of up to 532 kGy under vacuum at room temperature and subsequently exposure to air, is enhanced by approximately three orders of magnitude as compared to that of the unirradiated polymer. The UV–Vis spectra of the irradiated polymers reveal the presence of fluorocarbon radicals, which increase with the irradiation dose. It is also observed in the UV–Vis and FTIR spectra that peroxy free radicals, unsaturated species (COF), and a carboxyl group (COOH) containing a carbon-oxygen double bond are formed by reactions of the fluorocarbon radicals with oxygen or water vapor in air. In addition, an increase in the hydrogen concentration is observed in the near-surface regions of the irradiated polymers by using an elastic recoil detection (ERD) technique. The production of charge carriers such as protons and oxonium ions (H₃O⁺) by the interaction of water vapor with the activating-radiation-induced defects leads to the enhancement of the proton conductivity.     

Gamma radiation induced changes in nuclear waste glass containing Eu

Gamma radiation induced changes were investigated in sodium-barium borosilicate glasses containing Eu. The glass composition was similar to that of nuclear waste glasses used for vitrifying Trombay research reactor nuclear waste at Bhabha Atomic Research Centre, India. Photoluminescence (PL) and electron paramagnetic resonance (EPR) techniques were used to study the speciation of the rare earth (RE) ion in the matrix before and after gamma irradiation. Judd-Ofelt (J-O) analyses of the emission spectra were done before and after irradiation. The spin counting technique was employed to quantify the number of defect centres formed in the glass at the highest gamma dose studied. PL data suggested the stabilisation of the trivalent RE ion in the borosilicate glass matrix both before and after irradiation. It was also observed that, the RE ion distributes itself in two different environments in the irradiated glass. From the EPR data it was observed that, boron oxygen hole centre based radicals are the predominant defect centres produced in the glass after irradiation along with small amount of E’ centres. From the spin counting studies the concentration of defect centres in the glass was calculated to be 350 ppm at 900 kGy. This indicated the fact that bulk of the glass remained unaffected after gamma irradiation up to 900 kGy.     

Types of paramagnetic centers in Cu2+ complexes with model neuromelanins

Electron paramagnetic resonance (EPR) spectroscopy was used to examine free radical properties of model neuromelanins obtained by oxidative polymerization of noradrenaline, adrenaline and dopamine. We compared the lineshape of the experimental spectra, type and concentration of free radicals in the analyzed samples. The effect of different concentrations of Cu²⁺ on free radicals in melanins was studied. The total concentration of free radicals (about 10¹⁸ to 10¹⁹ spin/g) in the studied melanins increases as follows: adrenaline-melanin < dopamine-melanin < noradrenaline-melanin. EPR spectra of dopamine-melanin and adrenaline-melanin were a single EPR line (ΔB _pp, 0.50 and 0.55 mT, respectively). o-Semiquinone free radicals with the characteristicg-value of 2.0040 exist in these melanins. EPR spectra of noradrenaline-melanin were a superposition of two lines (ΔB _pp, 0.45 and 0.81 mT). o-Semiquinone free radicals were responsible for the narrower component. Nitrogen free radicals with ag-factor of 2.0030 were probably responsible for the broader component. Paramagnetic copper ions quenched the EPR signals of melanin free radicals in the studied samples. For melanin-Cu²⁺ complexes, broad EPR lines (ΔB _pp, 10–32 mT) of copper ions with ag-value of about 2.1 appeared. The influence of the microwave power on the EPR spectra of these complexes demonstrated the fast spin-lattice relaxation in the copper system in melanins.     

Spectral analysis of paramagnetic centers induced in human tooth enamel by x-rays and gamma radiation

Based on study of spectral and relaxation characteristics, we have established that paramagnetic centers induced in tooth enamel by x-rays and gamma radiation are identical in nature. We show that for the same exposure dose, the intensity of the electron paramagnetic resonance (EPR) signal induced by x-radiation with effective energy 34 keV is about an order of magnitude higher than the amplitude of the signal induced by gamma radiation. We have identified a three-fold attenuation of the EPR signal along the path of the x-radiation from the buccal to the lingual side of a tooth, which is evidence that the individual had undergone diagnostic x-ray examination of the dentition or skull. We have shown that the x-ray exposure doses reconstructed from the EPR spectra are an order of magnitude higher than the applied doses, while the dose loads due to gamma radiation are equal to the applied doses. The data obtained indicate that for adequate reconstruction of individual absorbed doses from EPR spectra of tooth enamel in the population subjected to the combined effect of x-radiation and accidental external gamma radiation as a result of the disaster at the Chernobyl nuclear power plant, we need to take into account the contribution to the dose load from diagnostic x-rays in examination of the teeth, jaw, or skull.     

Influence of 60Co gamma irradiation on the structural and optical properties of 2-aminopyridinium 4-nitrophenolate 4-nitrophenol crystals

In this article, effect of gamma irradiation on the structural and optical properties of 2-aminopyridinium 4-nitrophenolate 4-nitrophenol (2AP4N) has been reported. The grown crystals of 2AP4N were exposed to ⁶⁰Co gamma rays with a dose of 50 kGy and 100 kGy. The radiation-induced effects were analyzed using X-ray diffraction, FT-IR, UV–visible, photoluminescence techniques. The refractive index was determined using a long arm spectrometer. The structural properties of the pristine and irradiated crystals were studied using powder XRD. The peak intensity decrease after irradiation may be attributed to the formation of point defects. The UV visible study reveals that the energy gap has decreased after irradiation and then has increased for the higher dose. The intensity variation in the PL spectra is due to colour center mechanism. The SHG efficiency of 2AP4N crystals was found to be unaffected by gamma irradiation.     

CMOS器件60Co γ射线、电子和质子电离辐射损伤比较

利用TRIM95蒙特卡罗软件计算了质子在二氧化硅中的质量阻止本领和能量沉积，比较了质子在二氧化硅中的电离阻止本领与核阻止本领，分析了质子在材料的表面吸收剂量与灵敏区实际吸收剂量的关系.利用⁶⁰Co γ射线、1MeV电子和2—9 MeV质子对CC4007RH和CC4011器件进行辐照实验，比较⁶⁰Co γ射线和带电粒子的电离辐射损伤情况.实验结果表明，⁶⁰Co γ射线、1MeV 电子和2—7MeV质子辐照损伤效应中，在0V栅压下可以相互等效； 关键词： γ射线 电子 质子 辐射损伤     

Identification of irradiated crab using EPR

EPR spectroscopy is a fast and powerful technique for the identification of irradiated food. Crab exoskeleton was divided into six parts: dactyl, cheliped, carapace, apron, swimming legs, and walking legs. Samples of the exoskeleton were prepared and irradiated to Cs-137 gamma radiation in the range (1.156–5.365 kGy). EPR spectra of unirradiated as well as irradiated samples were recorded and analyzed. Response to gamma radiation was plotted for each part of the exoskeleton, dactyl was found to be the most sensitive part, followed by the apron (38%), cheliped (37%), walking legs (30%), swimming legs (24%), and carapace (21%) relative to the dactyl response.     

Electron paramagnetic resonance study of gamma-irradiated potassium hydroquinone monosulfonate single crystal

Gamma-irradiated potassium hydroquinone monosulfonate (PHM) single crystals were investigated between 125 and 300?K using the electron paramagnetic resonance (EPR) technique. Between 125 and 300?K no changes in the spectra have taken place. The spectra were found to be temperature independent. The investigation of EPR spectra of irradiated single crystals of PHM showed the presence of two PHM anion radicals. The g values of the radiation damage centers observed in the PHM single crystal and the hyperfine structure constants of the free electron with nearby protons were obtained.     

Secondary doses delivered to an anthropomorphic male phantom under prostate irradiation with proton and carbon ion beams

Secondary radiation exposure of patients undergoing radiation therapy with light ions is of great concern due to possible tissue damage and risk of induction of secondary cancers.Secondary particles such as neutrons, protons and heavier ions are produced when the primary ions interact through nuclear inelastic reactions with the beam-line components, and with the tissues of the patient.Evaluations of secondary doses delivered to an anthropomorphic male phantom under prostate irradiation with ¹H and ¹²C ion beams with energies 172 MeV and 330 MeV/u, respectively, have been performed with the Monte Carlo code SHIELD-HIT.Fluences of secondary particles with atomic mass A = 1–7 and energies up to 200–600 MeV/u are observed in organs even at larger distances (40–50 cm) from the irradiated volume. The secondary absorbed doses in selected organs are discussed taking into account the dose contribution from secondary neutrons, and the contribution from charged fragments that are not the products of neutron interactions. For ¹²C ion irradiation, a substantial contribution to the absorbed organ dose is due to charged fragments. This contribution decreases from 81% in the organs close to the irradiated volume to 35–40% in the organs at larger distances.