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Öğe EPR study of radicals produced by gamma-irradiation in marine mollusc (Venus sp.) fossils(TAYLOR & FRANCIS LTD, 2004) Koseoglu, R; Koksal, F; Ciftci, EIn this study, gamma-irradiated marine mollusc (Venus sp.) fossils were investigated by electron paramagnetic resonance (EPR) at ambient temperature. Powder X-ray diffraction technique indicates that the Venus sp. fossils were made mainly of CaCO3. Before gamma-irradiation, the EPR lines of the powder of fossil samples showed the existence of Mn2+ (I = 5/2, 100% natural abundance) ions with g(av) = 2.0055 and A(av) = 9.4 mT gamma-Irradiation-induced additional defects in Venus sp. fossil were attributed to axial CO3- (gperpendicular to = 2.0171, g// = 2.0048), orthorhombic CO2- (g(x) = 2.0030, g(z) = 2.0018, g(y) = 1.9973, g(av) = 2.0007), freely rotating CO2- (g(iso) = 2.0007), isotropic SO2- (g = 2.0057), axial SO3- (g perpendicular to = 2.0036, g// = 2.0024) and isotropic SO3- (g = 2.0032) free radicals. The g-values of these free radicals were compared with the literature data belonging to similar defects.Öğe Identification of paramagnetic radicals in gamma-irradiated natural diatomite minerals by electron paramagnetic resonance(ELSEVIER SCIENCE BV, 2005) Koseoglu, R; Koksal, F; Ciftci, E; Akkurt, MIn this study, gamma-irradiated natural diatomite minerals were investigated by electron paramagnetic resonance (EPR) spectroscopy at ambient temperature. The paramagnetic radicals produced by gamma-irradiation in natural diatomite minerals at ambient temperature were free radicals. These centers were found to be perfectly attributed to CH3, PO42-, CO2-, organic (probably, humic or fluvic acid), SO2- and SO3- observable at below 20 mW microwave power. The g values of all the paramagnetic centers were obtained, and some of their a values were reported. The results were found to be consistent with the existing literature data and theoretical predictions for similar paramagnetic centers. (C) 2004 Elsevier B.V. All rights reserved.Öğe Lead-arsenic soil geochemical study as an exploration guide over the Killik volcanogenic massive sulfide deposit, Northeastern Turkey(ELSEVIER SCIENCE BV, 2005) Ciftci, E; Kolayli, H; Tokel, SA mountainous terrain, the eastern Pontide tectonic belt, located in northeastern Turkey, contains more than 60 known volcanogenic massive sulfide (VMS) deposits that differ in reserves (0.1-30 million tonnes) and grades. Soil geochemistry is conventionally used in exploration programs to discover concealed VMS deposits in the region. In the present study, Pb and As element pair were used as pathfinder elements to investigate the relationship of their anomalies to a completely delineated ore deposit (Killik VMS deposit) in an orientation survey that served as a natural physical model. Two hundred forty soil samples were analyzed in the present study. The two elements, which represent the opposite ends of the mobility range, revealed high contrast and overlapped each other at the location of the ore deposit due to enhancement of the anomalies by hydromorphic dispersion, which is an indication that soil samples would produce reliable results. The successful delineation of the deposit is remarkable considering the rough topography and the climatic limitations. Previously the extremely moist and temperate climate was thought to cause excessive leaching of the trace element pathfinders from the ore deposits to produce extensive anomalies usually extending away from the mineralization thus, leading to erroneous results and/or extensive anomalous areas. But the present research has shown that the method can be used effectively if the sampling and data evaluation is carefully conducted. (C)\ 2005 Elsevier B.V. All rights reserved.
