Yazar "Koksal, F" seçeneğine göre listele

Listeleniyor 1 - 5 / 5
  • Küçük Resim Yok
    Öğe
    Detection of free radicals in gamma-irradiated seasnail hard tissues by electron paramagnetic resonance
    (PERGAMON-ELSEVIER SCIENCE LTD, 2003) Koseoglu, R; Koksal, F
    Gamma-irradiated seasnail (from family of Helix lukortium) hard tissues (CaCO3) were investigated by electron paramagnetic resonance (EPR) at room temperature. The radicals produced by gamma-irradiation in seasnail were attributed to orthorhombic C-. O-2(-), freely rotating C-. O-2(-), orthorhombic C-. O-3(-), axial C-. O-3(-), and axial C-. O-3(3-) free radicals. Unirradiated seasnail hard tissues also feature Mn2+ ions in their EPR spectra. The hyperfine values were determined for the C-13 nucleus in the orthorhombic C-. O-2(-) and axial C-. O-3(3-) free radicals and for the manganese impurity ions. The g values of all the free radicals have been measured. The results were compared with the literature data for similar defects. (C) 2003 Elsevier Ltd. All rights reserved.
  • Küçük Resim Yok
    Öğe
    EPR of gamma irradiation induced radicals in NaHCO3, CsHCO3 and Na2CO3
    (PERGAMON-ELSEVIER SCIENCE LTD, 2000) Koksal, F; Koseoglu, R
    In this study gamma irradiated NaHCO3, CsHCO3 and Na2CO3 were investigated at room temperature. The radicals induced by gamma irradiation in NaHCO3 were found to be (CO3-)-O-. (HCO3-)-O-. and (CO2-)-O-.; in CsHCO3 the species were attributed to (HCO3)-O-.; and in Na2CO3 to (CO3)-O-. and (CO2-)-O-. radicals. The hyperfine parameters for the hydrogen in (HCO3)-O-., and the C-13 nucleus in (CO2-)-O-. radical have been determined. The results were compared with literature data for similar compounds and the EPR properties of the (CO2-)-O-. radical were discussed. (C) 1999 Elsevier Science Ltd. All rights reserved.
  • Küçük Resim Yok
    Öğe
    EPR study of radicals produced by gamma-irradiation in marine mollusc (Venus sp.) fossils
    (TAYLOR & FRANCIS LTD, 2004) Koseoglu, R; Koksal, F; Ciftci, E
    In 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.
  • Küçük Resim Yok
    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, M
    In 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.
  • Küçük Resim Yok
    Öğe
    Synthesis, spectroscopy and redox chemistry of bis(N-aryl-3,5-di-tert-butylsalicylaldiminato)-copper(II) complexes
    (TAYLOR & FRANCIS LTD, 2004) Kasumov, VT; Koksal, F; Koseoglu, R
    A series of new bis(N-aryl-3,5-di-tert-butylsalicylaldiminato)copper(II) complexes (I), prepared from 3,5-di-tert-butylsalicylaldehyde and mono-substituted anilines, X-C6H4NH2 (X = H, o-F, Cl, Br, CH3, CH3O; p-F, Cl, Br, CH3, CH3O, t-Bu and 5,6-benzo), and their spectroscopic properties as well as electrochemistry and reactivity toward PPh3 are described. Comparison of g(parallel to) (2.223-2.249), A(parallel to) (150-170 G) tensors and the axial symmetry parameter, g(parallel to)/A(parallel to), (140-155 cm) of I with those of model Cu(II) complexes reveals that the coordination site is distorted from square planar toward tetrahedral geometry. The di-tert-butyl groups on the salicylaldehyde moiety unlike those introduced on the aniline rings do not facilitate reactivity toward PPh3. Electrochemical studies of I in acetonitrile solutions reveal highly irreversible behavior, due to chemical or stereochemical changes subsequent to electron transfer. In the oxidation of some complexes with (NH4)(2)Ce(NO3)(6) in acetonitrile at 300 K, along with decreasing ESR signals of Cu(II), the appearance of coordinated phenoxyl radical signals centered at g = 2.004 were detected. The CV studies on acetonitrile solutions of I revealed well-resolved quasi-reversible redox waves at E-1/2(1) = 0.61-0.99 V and E-1/2(1) = 1.09-1.23 V (vs. Ag/AgCl) attributable to ligand-centered oxidation processes to yield corresponding coordinated phenoxyl radical species such as Cu(II)(phenoxyl)(phenolate) and Cu(II)(phenoxyl)(2).