γ-Irradiation effects on the thermal decomposition behaviour and IR absorption spectra of piperacillin

The thermal decomposition behaviour of unirradiated and pre-γ-irradiated piperacillin (pipril) as a semi-synthetic penicillin antibiotic has been studied in the temperature range of (273–1072?K). The decomposition was found to proceed through three major steps both for unirradiated and γ-irradiated samples. Neither appearance nor disappearance of new bands in the IR spectrum of piperacillin was recorded as a result of γ-irradiation but only a decrease in the intensity of most bands was observed. A degradation mechanism was suggested to explain the bond rupture and the decrease in the intensities of IR bands of γ-irradiated piperacillin.     

Spectrum of aquoluminescence from γ-irradiated sodium chloride in the presence of activators: Fluorescein and eosin

The spectra of light emitted when γ-irradiated sodium chloride dissolves in pure, and in fluorescein- and eosin-doped, water have been measured. The spectrum observed with pure water is similar to the thermoluminescent spectrum of the γ-irradiated sodium chloride; the spectra with doped water are similar to the photoluminescent spectra of the dopants.     

Effect of γ-irradiation on optical and chemical properties of CR-39 polymer

CR-39 polymer samples were irradiated with γ-irradiation up to dose ranging from 500 to 2000 kGy. The virgin and γ-irradiated polymer samples were investigated using UV–visible spectroscopy and Fourier transform infrared (FTIR) spectroscopy. In the present work, the Urbach energy was calculated using the Urbach edge method. Also, the direct and indirect energy band gaps in virgin and γ-irradiated CR-39 polymer samples were calculated. The values of indirect energy band gap were found to be lower than the corresponding values of direct energy band gap. The decrease in the optical energy band gap with increasing γ-irradiation dose was discussed on the basis of γ-irradiation-induced modifications in CR-39 polymer. The correlation between optical energy band gap and the number of carbon atoms in a cluster with modified Tauc's equation was also discussed. The FTIR spectra show considerable changes due to γ-irradiation, indicating that the detector is not chemically stable.     

Application of the model-free approach to the study of non-isothermal decomposition of un-irradiated and γ-irradiated hydrated gadolinium acetylacetonate

The non-isothermal decomposition of unirradiated and γ-irradiated hydrated gadolinium acetylacetone with 10² kGy γ-ray absorbed dose was carried out in air and in nitrogen atmospheres and in the temperature range of 25–1000°C. The results indicate that gadolinium acetylacetonate decomposes through four main decomposition steps leading to the formation of intermediate products whose chemical structure is independent of the gas atmosphere applied and on the investigated absorbed dose. The final product at 820°C was found to be Gd₂O₃ irrespective of the gas atmosphere and the irradiation conditions. The non-isothermal data were analyzed using linear Flynn–Wall–Ozawa and non-linear Vyazovkin (VYZ) iso-conversional methods. The results of the application of these free models on the present kinetic data showed that the activation energy, E_a is independent of α in a very wide conversion range (0.1–0.9) indicating that the decomposition process is controlled by a unique kinetic model. The results of the model-fitting analysis showed that the decomposition course of the four decomposition steps of hydrated gadolinium acetylacetone was controlled by the D₃ Jander diffusion model. Pure phase of Gd₂O₃ nanoparticles was obtained by thermal oxidation of γ-irradiated GdAcAc.3 H₂O at 800°C for 6 h. X-ray diffraction, transmission electron microscopy (TEM) and atomic force microscopy (AFM) techniques were employed for characterization of the as-synthesized nanoparticles. This is the first attempt to prepare Gd₂O₃ nanoparticles by solid-state thermal decomposition of γ-irradiated hydrated gadolinium acetylacetone.     

Luminescence,optical and laser Raman scattering studies on γ -irradiated terbium-doped potassium iodide crystals

This paper reports the thermoluminescence (TL), optical absorption and other laser Raman scattering studies performed on terbium-doped KI crystals γ-irradiated at room temperature. Photoluminescence studies confirm the presence of terbium ions in the KI matrix in their trivalent form. Formation of V₃- and Z₁-centres on F-bleaching of γ-irradiated crystals was observed. The characteristic emission due to Tb³⁺ ions in the spectral distribution under optically stimulated emission and TL emission confirms the participation of the Tb³⁺ ions in the recombination process. The Raman bands were identified as the totally symmetric vibration modes of f.c.c. species KI:Tb³⁺.     

γ-Radiolysis of LiF

Abstract

Data are reported of optical absorption, magnetic susceptibility, mass and mass density measurements, which were carried out on γ-irradiated single crystals of lithium fluoride. The results show that the radiation damage in the γ-irradiated samples is strikingly similar to that in the neutron-irradiated specimens. A quantitative observation, however, reveals differences which give experimental evidence for the statement that the F-centres occur in a more aggregated form in the γ^? than in the neutron-irradiated crystals.     

掺铋BaF2晶体的制备及其近红外发光研究

通过温度梯度法制备了Bi₂O₃:BaF₂以及BiF₃:BaF₂晶体.在Bi₂O₃:BaF₂晶体中观察到了发光峰位于961 nm,半高宽202 nm的超宽带红外发光.在BiF₃:BaF₂晶体中检测到Bi²⁺和Bi³⁺可见区的发光,但是没有观察到红外发光.通过γ射线辐照实现了BiF₃:BaF₂晶体的近红外发光, 发光峰位于1135 nm,半高宽192 nm.讨论了Bi₂O₃和BiF₃掺杂BaF₂晶体的红外发光的机理. 关键词： 近红外发光 铋 氟化钡晶体 γ辐照     

Effect of capping on the mechanoluminescence of γ-irradiated ZnS:Cu nanophosphors

Mechanoluminescence (ML) properties of γ-irradiated and non-irradiated capped ZnS:Cu nanophosphors have been investigated. The nanoparticles were prepared by wet chemical method using different capping agents. The samples were characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). ML was excited impulsively by dropping a load on to the sample. Two peaks have been observed in the ML intensity versus time curve. It has been found that ML intensity rises with time, attains a maximum and then decays. The ML intensity of γ-irradiated SiO₂ capped ZnS:Cu nanophosphors was found to be the highest amongst the presently investigated nanophosphors. Mechanism of ML has been explained on the basis of piezoelectrically induced charge carrier detrapping model.     

Radiation-induced synthesis of RuO2 nanoparticles by thermal decomposition of Ru-tris-acetylacetonate

Pure-phase RuO₂ nanoparticles were obtained by thermal decomposition of unirradiated and γ-irradiated Ru-tris-acetylacetonate precursors. Several influencing factors including absorbed dose, calcination times and temperatures and addition of surfactants were thoroughly investigated. The newly synthesized RuO₂ nanoparticles were characterized by X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The results showed that the best conditions for the preparation of mono-dispersed RuO₂ nanoparticles were achieved by calcinations of unirradiated Ru-tris-acetylacetonate for 6 h at 600°C. For γ-irradiated Ru-tris-acetylacetonate with 10² Gy total γ-ray doses, the optimal conditions for RuO₂ preparation were calcination for 2 h at 200°C. Thermal stability of RuO₂ nanoparticles was studied using thermogravimetric (TG) and differential thermal analysis (DTA) techniques, and the results were evaluated and discussed.     

Electron spin resonance spectrum for a radical in γ-irradiated N-iodosuccinimide

A radical exhibiting a very large hyperfine coupling to ¹²⁷I, together with a small coupling to ¹⁴N, formed in γ-irradiated N-iodosuccinimide at 77 K is identified as a σ* radical anion in which the added electron is accommodated primarily in the N-I antibonding σ-orbital.     

A New Heavy Neutron-rich Isotope 238Th

A new nuclide ²³⁸Th has been produced via multinucleon transfer reaction induced by 60MeV/u ¹⁸O ion irradiation of natural uranium. The thorium was radiochemically separated from the mixture of uranium and its reaction products. The activity of thorium was measured by using a HPGe detector and a planar HPGe detector. The ²³⁸Th has been identified for the first time by measuring the growth and decay of the γ-rays from its daughter ²³⁸Pa. The half-life of 238Th was determined to be (9.4±2.0)min. In addition,a new (89.0±0.3)keV γ-ray with T_1/2=(8.9±1.5)min was observed and assigned to ²³⁸Th decay based on the measurement of transition energy and half life.     

γ-Irradiation effects on the thermal and optical properties of undoped and eosin doped 70/30 (wt/wt%) PVA/glycogen films

Differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), UV/visible spectra and colour detection of pristine and γ-irradiated undoped and eosin-doped 70/30 (wt/wt%) PVA/glycogen has been measured. The kinetic parameters such as the activation energy, entropy, enthalpy and free energy for all investigated samples were determined using Coats–Redfern relation. The shift of T_g position towards lower temperatures with increasing γ-doses reflect that the degradation process is the predominant one. The values of absorbance and optical parameters in UV/visible range for γ-irradiated blend sample doped with eosin showed no significant variation with increasing γ-doses. This reflects that the addition of eosin to 70/30 (wt/wt%) PVA/glycogen makes it more resistant to γ-radiolysis. The calculated colour parameters such as L¹, U¹, V¹, C¹, hue and Y_e were found to be dependent on addition of eosin and γ-irradiation.     

Radiation-induced synthesis of ZrO2 nanoparticles by thermal decomposition of zirconium acetylacetonate

ZrO₂ nanoparticles were obtained by the thermal decomposition of un-irradiated and γ-irradiated zirconium acetylacetonate (ZrAcAc) precursors. Several influencing factors, including absorbed dose, calcination times, calcination temperatures and addition of surfactants, were thoroughly investigated. The results showed that the best conditions for the preparation of ZrO₂ nanoparticles were achieved by calcinations of ZrAcAc for 5 h at 600°C in the presence of 1 mL of benzyl alcohol as the surfactant. Different phases, morphologies and sizes for the as-prepared ZrO₂ nanoparticles were obtained by varying the dose of γ-ray absorbed. ZrO₂ nanoparticles obtained by thermal decomposition of un-irradiated ZrAcAc have mixture of monoclinic and tetragonal crystal systems, the particles are monodispersed with an irregular shape. In the case of γ-irradiated ZrAcAc with 10, 10² and 10³ KGy, ZrO₂ nanoparticles have only a tetragonal system with different morphologies depending on the γ-ray dose absorbed. Thermal stability of ZrO₂ nanoparticles was studied using thermogravimetric/differential thermal analyzer techniques. Thermodynamic and kinetic parameters were evaluated and discussed.     

A new treatment for the interpretation of radical decay in γ-irradiated polyethylene

The decay of polymer radicals in γ-irradiated polyethylene as measured by EPR is discussed from the viewpoint of a continuous but not constant distribution over the activation free energy and of the kinetic constants. The possibility of determining this distribution from experimental results alone is shown. In addition, the new treatment enables us to obtain more clearly the various temperature regions in which radical decay takes place most rapidly, and this allows a distinction by EPR, for instance, even between several kinds of low-density polyethylene.     

EPR investigations on γ-irradiated 4-hydroxyacetophenone single crystals: an NLO material

The single crystals of 4-hydroxyacetophenone (4HAP) were grown by the solution growth technique and characterized by X-ray diffraction, UV–VIS, FT-IR, and FT-Raman techniques. TGA–DTA analyses have also been carried out. Electron paramagnetic resonance spectra of γ-irradiated 4HAP were recorded and the spin Hamiltonian parameters were evaluated.     

Kinetic studies for the non-isothermal decomposition of un-irradiated and γ-irradiated ruthenium(III) acetylacetonate

Kinetic studies for the non-isothermal decomposition of un-irradiated and γ-irradiated ruthenium(III) acetylacetonate in air were carried out. The results show that the decomposition proceeds in one major step in the temperature range of 150–250 °C with the formation of RuO₂ as a final solid residue for un-irradiated Ru(acac)₃. For γ -irradiated Ru(acac)₃ with 10² KGy total γ-ray dose, the decomposition goes eventually to completion with almost 100% decomposition and proceeds in one major step, which contains four overlapping decomposition stages in the temperature range of 200–320 °C. The kinetics is shown to be non-isothermal, using both model-fitting and model-free approaches. Infrared (IR) spectroscopy and X-ray powder diffraction techniques were employed to follow the chemical composition of the solid residue obtained at different temperatures.     

Decay of 59.3 min 128Sn to levels of 128Sb

The γ-ray spectra associated with the decay of 59.3 min ¹²⁸Sn have been measured with Ge(Li) detectors. In order to recognize γ-rays of ¹²⁸Sn and ^128mSb, the decay and/or growth of γ-rays emitted from a tin sample separated chemically from fission products were measured. The decay of ¹²⁸Sn is followed by the intense Sb X-rays and 32.1, 45.8, 75.1, 80.9, 115.9, 152.6, 404.4, 482.3, 557.3 and 680.2 keV γ-rays. On the basis of the measured singles and γ-γ coincidence spectra and the analysis of intensities of true sum peaks, a new decay scheme has been constructed. The 10.0 min isomer in ¹²⁸Sb decays by β-emission (96.4%) to excited levels in ¹²⁸Te and by an isomeric transition (3.6 %) to the 9.1 h ground state.     

Gamma Irradiation Effects on the Electric Conductivity Behaviour and IR Absorption Spectra of some Haloacetato and Mixed Thiazoles-Haloacetato Transition Metal Complexes

Gamma irradiation effects on the electric conductivity behaviour and IR absorption spectra of some thiazole and haloacetato complexes were investigated. A comparison is made between the rate and activation energies of the thermal annealing of electrical properties of pure and γ-irradiated samples. A mechanism is suggested to explain the observed decrease in the intensity of metal-oxygen bond in the IR spectra of the complexes as a result of γ-irradiation.     

Isothermal decomposition of γ-irradiated palladium acetate

The isothermal decomposition of un-irradiated (pristine) and pre-γ-irradiated palladium acetate was studied in the temperature range (498–508 K) and in air using the isothermal thermogravimetric technique. The data were analysed using various solid state reaction models. The results showed that the kinetics of isothermal decomposition of palladium acetate was governed by random nucleation reaction (Erofe'ev equation A ₃). The activation energies of the main decomposition process for un-irradiated and pre-γ-irradiated samples were calculated. The change in texture and crystal structure of the investigated palladium acetate by γ-irradiation was studied using electron microscopy and X-ray diffraction techniques.