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Plutonium in the form of oxide is stored in plastic vials and bottles during its analysis for trace metal assay. Due to radiation damage and moisture, small amount of oxide samples were found to be adhering to surface of vials/bottles. This required methods for safe disposal. Methods involving wet chemical and dry cleaning procedures were evaluated for effective removal of sticking α active plutonium oxide powder from these vials for their safe disposal. Dry cleaning method for removal of plutonium activity was found to be effective method for disposal of storage vial, while wet chemical method was found to be more suitable for removal of plutonium from damaged PVC bottles. The recovered Pu was checked for chemical purity for 24 analytes using glove box adopted high resolution inductively coupled plasma atomic emission spectrometry.

LiAl5O8 doped with varying concentrations of Eu were synthesized by a solid state reaction route. Phase purity of the prepared phosphors was determined using X-ray diffraction technique. Dynamic light scattering technique was used to estimate the average particle size of the synthesized products that was found to be ~ 110 nm. The doped phosphor samples exhibited strong excitation band in the range 210–290 nm with 613 nm emission suggesting the stabilisation of trivalent Eu. With 394 nm (UV) excitation, strong visible luminescence was observed at 613 nm corresponding to the 5D0 → 7F2 transition of the Eu3+ ions. The emission parameters were optimised by varying the dopant ion concentration and annealing temperature. The intensity parameters (Ωλ, λ = 2, 4 and 6), radiative transition probabilities (AR), radiative lifetime (τR) and branching ratios (β) for the system were evaluated in the framework of the model given by Judd–Ofelt. The CIE coordinates for the system were evaluated by adopting standard procedure, which suggested that the system has enough potential to be used as a red phosphor.

A procedure was developed for determination of Np using HR Sequential ICP-AES. Mutual interference and background free spectral lines of Np at 295.66, 297.43, 297.49, 302.64 nm were identified. The samples of higher concentration (10–20 µg/mL) of Np had been analyzed. Analytical values of 10–20 µg/mL samples were found to be in good agreement with the expected amounts. The concentration of Np between 2 and 4 μg/mL slightly affected as compared to higher concentration. In U/Pu, Np-295.66, 297.43 nm lines were monitored which showed noticeable enhancement of their intensities. The repetitive analyses showed that the precision was better than 2% RSD.

Nanocrystalline ThO2:Sm3+ was synthesized using wet-chemical route and characterized using X-ray diffraction (XRD), photoacoustic (PA) and photoluminescence (PL) spectroscopy. PA absorptions of Sm3+ doped samples are found to be quite weak as compared to Nd3+, while PL of Sm3+ was intense. As the energy gap between lowest luminescent levels and highest non-luminescent level in samarium ion is around 7000 cm−1; it is highly fluorescing compared to Nd3+ which has close by levels. Through photoacoustic data it was pointed out that large covalent character exists in ThO2:Nd3+ compared to ThO2:Sm3+.

Selective separation of uranium using bis(2,4,4-trimethylpentyl)phosphinic acid in xylene and C8mimNTf2 was investigated. For ionic liquid based system, the extraction kinetics was found to be slower with the predominance of ion exchange mechanism through [UO2(NO3)·2L]+, while for xylene based system solvation mechanism. The nature of the extracted species was found to be different in both the media as observed in luminescence study. Ionic liquid based system was more radioresistant than that of molecular diluents. Na2CO3 was successfully used for stripping. The selectivity was investigated by processing simulated high level waste of pressurized heavy water reactor origin.

The applicability of energy dispersive X-ray fluorescence spectrometry as an analytical technique for the determination of a few metallic impurities such as Ca, Cr, Cu, Fe, Mn, Pb, and Zn in alumina (Al2O3) matrix was investigated. A series of Al2O3 standards containing the elements of interest in the range 10–1000 ppm was prepared and the spectrometer conditions were optimized to obtain calibration plots for the various analytes that could be further used for the analysis of actual samples. The present method serves as an alternative to currently used AES method for analytes expected in the concentration range 50–1000 ppm.

The use of serpentine as a potential nuclear shielding material necessitates a chemical quality control of the samples before its use in reactors. With this in view, characterization of these mineral samples was carried out using inductively coupled plasma atomic emission spectrometry (ICP-AES) and Instrumental neutron activation analysis (INAA) methods. The analytical results obtained by both ICP-AES and NAA techniques were found to be comparable. Na, Cr, Co, Zn, and Cu were found to be present in all samples of Indian origin while Ga, Ag, Ni, and Cd were found to below the limits of detection. A comparison on the detection limits of elements of interest was also carried out by both the analytical techniques and found to be in good agreement. An infrared spectroscopic investigation was also carried out on all the mineral samples. Bands at 3,689 and 3,648 cm−1 were attributed to inner and outer hydroxyl stretching of Mg–OH, respectively. The weak and broad band centered around 3,416 cm−1 was assigned due to the stretching vibrations of the adsorbed water molecules while three bands at 1076, 1022 and 968 cm−1 were prescribed to the vibrations of the SiO4 tetrahedra.

We report the synthesis of Th1–xMnxO2 (x = 0, 0.001, 0.002, 0.004, and 0.01 wt%) nanoparticles by the urea combustion method using thorium nitrate gel followed by heat treatment at a higher temperature (T). The obtained Th1–xMnxO2 nanocrystals were characterized by x-ray diffraction (XRD), direct-current magnetization (M) measurements and electron paramagnetic resonance (EPR). XRD analysis revealed that Th1–xMnxO2 crystallizes in the cubic structure (Fm3m). M measurements showed ferromagnetic ordering at room temperature for Th0.99Mn0.01O2 samples annealed at 775 K. An intense and broad ferromagnetic resonance (FMR) having linewidth of ∼1200 G, was observed at relatively lower fields in the EPR spectra of Th0.99Mn0.01O2 samples annealed at 775 K, indicating the presence of a ferromagnetic phase at room temperature. EPR measurements were used to estimate the number of spins involved in the ferromagnetic ordering. Out of the total Mn present in Th0.99Mn0.01O2 samples, about 25% of the Mn2+ ions were found to be responsible for the ferromagnetic ordering. In addition to the FMR signal, a weak hyperfine sextet was observed at g = 2.0048 (55Mn, I = 5/2), which corresponds to the −1/2 ↔ +1/2 transition of Mn2+ ions, suggesting its presence at thorium sites (uncoupled spins). X-ray photoelectron spectra indicated that the manganese ions exist mainly as Mn2+, Mn3+, and Mn4+. The room-temperature ferromagnetism may be attributed to the coupling between these Mn2+ ions at thorium sites in ThO2 rather than due to the formation of any metastable secondary phases.

The radiolytic stability of TBP, DHOA, Cyanex 923 and Cyanex 272 in ionic liquid vis a vis molecular diluents have been evaluated for the extraction of thorium. The decrease in DTh value was found to follow the trend of irradiated (Xylene + ligand) > irradiated (ionic liquid + ligand). Ionic liquid was found to act as a sink to protect the ligand functionality from radiation damage. On gamma exposure, the other metal ions were also found to be co-extracted into organic phase from simulated high level waste solution of fast breeder reactor origin consequently reducing the selectivity. The reduction in selectivity on gamma exposure was found to be more in xylene than C8mimNTf2 based systems.

Thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) studies were carried out on gamma-irradiated europium-doped yttrium borate samples in the temperature range 300–600 K. TSL studies showed the presence of two glow peaks, a relatively weaker one at 390 K and an intense one at around 550 K. Room-temperature EPR spectrum of irradiated samples revealed the formation of two hole trapped radicals, namely, BO32− and O2−. Temperature variation studies showed drastic reduction in the EPR signal intensities of these radicals around 390 and 550 K indicating thermal destruction of O2− and BO32− radicals, respectively. The observed TSL emission is caused by the recombination of thermally released holes from O2− and BO32− radical ions with electrons. The energy released in electron-hole recombination process is used for the excitation of Eu3+ ion resulting in TSL glow peaks. TSL emission studies confirmed that Eu3+ acts as luminescent center for both the peaks.

Thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) investigations were carried out on gamma irradiated SrBPO5 samples doped with CeO2 and co-doped with CeO2 and Sm2O3. On gamma-irradiation at room temperature, BO32-, O2- and O- radicals were produced. It was seen that the O- radical ion disappeared in the sample annealed at 500 K. It is proposed that the recombination between trapped electrons and O- radical ions results in transfer of recombination energy to the impurity centre Ce3+ resulting in TSL glow peak at 485 K. In the case of co-doped samples energy transfer occurs between Ce3+ to Sm3+ resulting in increase in the intensity of glow peak at 485 K.

Microwave absorption studies have been carried out on MgB2 superconductor using a standard X-band EPR spectrometer. The modulated low-field microwave absorption signals recorded for polycrystalline (grain size ∼ 10 µm) samples suggested the absence of weak-link character. The field dependent direct microwave absorption has been found to obey a ✓H dependence with two different slopes, which indicated a transition from strongly pinned lattice to flux flow regime.

Thermally stimulated luminescence (TSL), electron paramagnetic resonance (EPR) and photo-acoustic spectroscopy (PAS) techniques were used to investigate the radiation induced centers in polycrystalline LaBa2F7 containing trace amounts of other rare-earths particularly Gd3+ and Sm3+. The TSL glow curve of LaBa2F7 after g-irradiation to a dose of 3 kGy had shown a weak TSL glow peak at 390 K and a much stronger one at 495 K. The EPR spectra of the g-irradiated LaBa2F7 samples showed the presence of O- and O2 - ions. Temperature dependence study of the EPR spectra showed that the thermal destruction of O- ion occurs in the 460-490 K temperature range. In g-irradiated samples, O- and F-centers were identified by PAS. The correlation of EPR and PAS results indicate that the prominent TSL glow at 495 K is associated with the thermal destruction of O- radical ion. The trap parameters viz. trap depth and frequency factor have been determined from TSL data.

Photo-EPR measurements carried out on Nd3+ -doped polyvinyl alcohol (PVA) films have shown that nearly 100% reduction occurs in the intensity of EPR of Nd3+ under in situ copper vapor laser (CVL) illumination (510.5 nm and 578.2 nm). The kinetics of decay and recovery were investigated. Photoacoustic (PA) spectra, observed under CVL pump condition had shown that the CVL induced changes were not due to photoinduced valence change, and that the CVL pumping creates highly favorable conditions for non-equilibrium population distribution in the excited electronic states. The complete disappearance of EPR under CVL pumping is attributed either to the possible equalization of population of |+〈 and |−〈 Zeeman components, through the decay of many excited states in the presence of magnetic field or configurational changes around Nd3+ shifting the resonance frequency. The former appears less probable in view of the relatively slower recovery of EPR signal.

In order to understand the mechanism of optical image storage in photorefractive polyvinyl alcohol (PVA) films, photo-EPR and photoacoustic spectral investigations were carried out on PVA films doped with Cr3+ and VO2+. The EPR spectrum of Cr3+ has shown reduction in intensity onin situ illumination with copper vapor laser (CVL). The decay and recovery of Cr3+ signal, with and without CVL illumination respectively, was monitored at different temperatures in 10–300 K region. These were found to obey a double exponential, with one time constant independent of temperature, and the other showing significant temperature dependence. From Τ(T), activation energy for the charge carrier transport in one of the processes was estimated to be 0.016 eV. The PA spectra showed shift towards lower wavelength side on consecutive runs. On the other hand, VO2+ doped PVA film has not shown any significant changes in intensity on laser illumination. These observations suggest (i) interaction of PVA matrix with excited Cr3+ and (ii) predominant non-radiative relaxation in VO2+: PVA system with no change in the oxidation state.

Photo-induced charge transfer and its kinetics were investigated in Bi12SiO20 in 10–300 K temperature range, using EPR of Fe3+ centre, underin situ illumination with copper vapour laser (CVL). The decay kinetics was found to follow double exponential behaviour. Relaxation of the photo-induced electron transfer to the preillumination condition occurred even at 10 K. Shallow traps were, therefore, associated with the electron trapping, leading to a better understanding of the fast photorefractive response of BSO.

In the fluorinated La2CuO4−x prepared using a solid state reaction with NH4HF2 as a fluorinating agent at 550 K at ambient pressure, superconductivity was detected by microwave and EPR techniques with aT c of 35 K.

We have recently reported our results on magnetic susceptibility and microwave absorption studies on Bi2Sr2Ca1−x Gd x Cu2O y and Bi2Sr2Ca1−x Y x Cu2O y . In the present work two important observations of these investigation, viz, the dependence ofT c on Gdconcentration and the absence of EPR-signals of Gd and Cu, are considered in greater detail. It is suggested that the microwave absorption by fluxon lattice might be playing one of the important and effective pathways for electron spin relaxation resulting in nonobservation of EPR signals.

The recent discovery1–3 of high-temperature superconductivity in the Y(La}–Ba–Cu–O system has generated intense experimental and theoretical activity. On the theoretical side, it has revived the discussion of different modes of pairing in solids4,5. Here we report some important features of the low-field electron spin resonance (ESR) spectrum in the superconducting phase of YBa2Cu3O7–x, giving evidence for the dimerization of electrons on copper pairs. An intense low-field resonance appears below the critical temperature, Tc, and exhibits unresolved hyperfine structure at temperatures below 70 K. The resonance field was found to be dependent on both temperature and microwave frequency. These are well-established features characteristic of copper pairs formed due to an exchange interaction. It appears that the individual spins responsible for superconductivity are formed and dimerized only at Tc, with their intensity sharply increasing below Tc. This observation appears to be a pointer towards the possibility of the disproportionation 2Cu3+ → Cu2+ + Cu4+ in adjacent octahedra, facilitated by coupling to local eg vibrations in the superconducting phase.