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Jayasheelan A.,GFGC | Manjunatha S.,GFGC | Yashodhara I.,University Science Instrumentation Center | Karunakara N.,University Science Instrumentation Center
Radiation Protection Dosimetry

The activity concentration of 226Ra, 232Th and 40K was measured for soil samples collected from 34 locations of Tumkur District, Karnataka, India, using HPGe detector. The activity concentration of 226Ra, 232Th and 40K varied from 9.6 to 71.6, 12.3 to 333.3 and 194.3 to 1527.7 Bq kg-1 with an average value of 33.15, 123.01 and 877.76 Bq kg-1, respectively. The absorbed and annual effective outdoor doses were found to be highest at Ponnasamudra with 258.98 nGy h-1 and 317.62 μSv and lowest at Sira with 36.42 nGy h21 and 44.67 μSv, respectively. The external hazard index ranged from 0.21 to 1.58 with an average of 0.75. It was significant in 11 locations as it exceeded unity. Source

Kiran N.,University Science Instrumentation Center | Suresh Kumar A.,University Science Instrumentation Center
Journal of Molecular Structure

Sodium-lead borophosphate glasses doped with different Dy3+ concentrations have been prepared and characterized through, XRD, FTIR, optical absorption and photoluminescence techniques. FTIR spectrum indicates the presence of BO3 and PO4 structural units. The optical absorption spectrum has been studied at room temperature and several bands have been observed. These bands have been assigned to the ground state 6H15/2 to several excited states. The bonding parameters have been evaluated based on the observed band positions. From the absorption spectrum, Judd-Ofelt (J-O) intensity parameters have been evaluated. By using J-O parameters radiative parameters such as transition probabilities, branching ratios and absorption cross section have been evaluated. The emission spectra have been studied for different concentrations of Dy3+ ions. The yellow/blue values due to 4F9/2 → 6H 13/2/4F9/2 → 6H15/2 luminescence intensity ratios of Dy3+ ions, increase with increasing concentrations, suggesting higher asymmetry and more covalent bonding character between Dy and oxygen ligands. The chromaticity coordinates were calculated from emission spectra and analysed with Commission International deI'Eclarige Color diagram. The life time of the 4F9/2 level has been measured and found to decrease with increase in Dy3+ ions concentration. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved. Source

Kiran N.,University Science Instrumentation Center | Kesavulu C.R.,Sv University | Suresh Kumar A.,University Science Instrumentation Center | Rao J.L.,Sv University
Physica B: Condensed Matter

Electron paramagnetic resonance (EPR), optical absorption, and luminescence spectral studies of Mn 2 ions doped in (30-x) (NaPO 3) 630PbO40B 2O 3xMnO 2 (x=1.0, 2.0, 3.0, 4.0, and 5.0 mol%) glasses have been studied. The EPR spectra exhibit resonance signals with effective g value at g eff≈2.02 with six line hyperfine structure. A weak resonance signal with effective g value at g eff≈4.3 is also observed for higher concentrations of Mn 2 ions. The EPR spectra of x =3.0 mol% of Mn 2 in sodiumlead borophosphate glass sample have been studied at various temperatures. It is observed that the resonance signal intensity decreases with increase in temperature. The optical absorption spectrum exhibits bands characteristic of Mn 2 ions in octahedral symmetry. From the analysis of the bands, the crystal-field parameter Dq and the Racah interelectronic repulsion parameters B and C have been evaluated. The emission spectrum exhibits single broad band in the green region. © 2011 Elsevier B.V. All rights reserved. Source

Srinivasulu K.,University Science Instrumentation Center | Omkaram I.,Sri Venkateswara University | Obeid H.,Lebanese University | Kumar A.S.,University Science Instrumentation Center | Rao J.L.,Sri Venkateswara University
Journal of Physical Chemistry A

Electron paramagnetic resonance (EPR), optical absorption, and FT-IR spectra of vanadyl ions in the sodium-lead borophosphate (Na 2O-PbO- B 2O 3-P 2O 5) (SLBP) glass system have been studied. EPR spectra of all the glass samples exhibit resonance signals characteristic of VO 2+ ions. The spin Hamiltonian parameters g and A are found to be independent of the V 2O 5 content and temperature. The values of the spin Hamiltonian parameters indicate that the VO 2+ ions in SLBP glasses are present in octahedral sites with tetragonal compression. The population difference between Zeeman levels (N) is calculated as a function of temperature for an SLBP glass sample containing 1.0 mol % VO 2+ ions. From the EPR data, the paramagnetic susceptibility (ξ) is calculated at different temperatures, and the Curie constant (C) is calculated from the 1/ξ versus T graph. The optical absorption spectra of the glass samples show two absorption bands, and they are attributed to V 3+ and V 4+ ions. The optical band gap energy (E opt) and Urbach energy (ΔE) are calculated from their ultraviolet absorption edges. It is observed that, as the vanadium ion concentration increases, E opt decreases and ΔE increases. The study of the IR absorption spectrum depicts the presence of BO 3, BO 4, PO 3, PO 4, and VO 5 structural units. © 2012 American Chemical Society. Source

Rajawat D.S.,University Science Instrumentation Center | Srivastava S.,Dayalbagh Educational Institute | Satsangee S.P.,University Science Instrumentation Center
International Journal of Electrochemical Science

A new carbon paste electrode modified with water hyacinth (Eichhornia Crassipes) was developed for the determination of mercury in aqueous sample using differential pulse anodic stripping voltammetry. First mercury was adsorbed on electrode surface at open circuit, following this the adsorbed mercury was determined by anodic stripping voltammetric scan from -0.5 to 0.5 V. Factors affecting sensitivity and precision of the electrodes, including amount of modifier, supporting electrolyte, accumulating solvent, pH of the accumulating solvent, accumulation time and scan rate were investigated. Optimized working conditions are defined as 5 % water hyacinth biomass of graphite powder, sodium hydroxide as supporting electrolyte, acetate buffer of pH 3 as an accumulating solvent and scan rate 50 mV/S. Linear calibration curves were obtained in the concentration range 400 μgL-1 to 800 μgL-1 of mercury for accumulation time of 10 min with limit of detection 195 μgL-1. This technique does not use mercury and therefore, has a positive environmental benefit. © 2012 by ESG. Source

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