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Öğe An electron paramagnetic resonance study on irradiated triphenylphosphinselenid single crystal(TAYLOR & FRANCIS LTD, 2014) Aras, Erdal; Karatas, Ozgul; Meric, Yasemin; Abbass, Hind Kh; Birey, Mehmet; Kilic, AhmetThe single crystals of triphenylphosphinselenid [C18H15PSe] were produced by slow evaporation of concentrated ethyl acetate solutions. These single crystals were exposed to Co-60 gamma (gamma) rays with a dose speed of 0.980kGy/h at the room temperature for 72h. The free radical over the sample was observed using electron paramagnetic resonance (EPR)-X band spectrometer. The EPR spectra were recorded between 120 and 400K. Furthermore, the sample irradiated was rotated in steps of 10 degrees and analyzed for different orientations of the crystal in the magnetic field. Only one radical structure was determined on the molecule. The hyperfine constants of the sample were found to be anisotropic. The average values of these constants and value of g were calculated as following: g=2.007656, a(Se)=37.47G, a(P)=27.44G, a(Ha)=17.28G, and a(Hb)=18.16G.Öğe An EPR Study On Cytosine Irradiated(WILEY, 2011) Usta, Ayhan; Vural, Hasibe Cingilli; Usta, Keziban; Aras, Erdal; Ceylan, Yusuf; Ozmen, AyhanIn this study, paramagnetic centers over the cytosine were formed by photolysis then these centers were investigated using EPR method. EPR signals were not recorded from non-irradiated the cytosine, but irradiated polycrystalline exhibited complex EPR spectra. For obtaining of cytosine polycrystalline, novel crystallization method was performed on powder cytosine. Effective crystallization conditions were achieved by adjustment of the concentration of the metal ions, chemical solutions, NaCl, KCl, glacial asetic acid, nitric oxide, percloric acid, glutamic acid, and pH of buffer. Cytosine (C4H5N2O) polycrystalline obtained were irradiated with Co-60 - rays at room temperature for 24 and 72 h. At the sample irradiated for 72 h, the paramagnetic centers were determined between 120 and 450 K by X-band EPR spectrometer. The spectra were found to be dependent slightly on temperature. Two cation radicals were determined in the structure and these were called Radicals I and II. The g and hyperfine constants were found to be a(H2a) = 61 G, a(N2) = 9.39 G, a(N1) = 7.15 G, and g(1) = 2.0026 for the Radical I; a(H3) = 10.57 G, a(H1) = 3 G, a(N3) = 6.72 G, a(N1) = 5.36 G for, and g(2) = 2.0034 the Radical II. Copyright (C) 2010 John Wiley & Sons, Ltd.Öğe An EPR study on single crystals of dimethyl-1,3-cyclohexanedione by gamma-rays(TAYLOR & FRANCIS LTD, 2012) Aras, Erdal; Usta, Ayhan; Erturk, Serkan; Asik, BiraySingle crystals of dimethyl-1,3-cyclohexanedione (C8H12O2) were produced by slow evaporation of the concentrated ethyl acetate solutions. These single crystals were exposed to Co-60 gamma-rays with a dose speed of 0.950 kGy/h at room temperature for 24, 48, and 72 h. The free radicals of the samples irradiated for 48 and 72 h were detected using electron paramagnetic resonance (EPR)-X-band spectrometer. EPR measurements were performed between 120 and 300 K. The sample irradiated for 48 h by gamma-rays was rotated in steps of 10 degrees at 298 K. The spectrum parameters were found to be dependent on the temperature. Two radicals were determined in the molecular structure irradiated. These radiation damage centers were called R1 and R2. The average values of g and the hyperfine coupling constants were calculated as follows: a(Ha) = 6.84 G, a(Hb) = 3.60 G, g = 2.0040 for R1, a(H) = 28 G, g = 2.0062 for R2.Öğe Electron paramagnetic resonance of gamma-irradiated single crystals of ethan-1,2 disulfonic acid disodium(ELSEVIER SCIENCE BV, 2012) Karatas, Ozgul; Aras, ErdalESR spectra of ethan-1,2 disulfonic acid disodium (C2H4Na2O6S2) irradiated by Co-60-gamma were recorded between 125 K and 300 K and for different orientations of the crystal in the magnetic field. The spectra were found to be temperature independent. In C2H4Na2O6S2 single crystal, the radiation damage centers caused by a Co-60-gamma source were determined as SO2 radical. For SO2 radical, a value of spectroscopic splitting factor g was calculated. (C) 2012 Elsevier B.V. All rights reserved.Öğe Electron paramagnetic resonance study of gamma (gamma)-irradiated methyl 4-methyl benzoate (C9H10O2)(TAYLOR & FRANCIS LTD, 2016) Karatas, Ozgul; Aras, Erdal; Karadag, A. Halide; Islek, YaseminIn this study, gamma ()-irradiated methyl 4-methyl benzoate (C9H10O2) single crystals were investigated and the structure of the free radical occurring by -irradiation was determined by using Electron paramagnetic resonance (EPR) technique. C9H10O2 single crystals were produced by slow evaporation with distilled water solution at room temperature. These single crystals were irradiated by Co-60-gamma-ray source with a dose speed of 0.981kGy/h at room temperature for 72h. The EPR spectra of irradiated C9H10O2 single crystals were recorded between 125 and 400K temperatures in steps of 10 degrees intervals at different orientations in magnetic field with an X-band EPR spectrometer. The spectra were found to be slightly anisotropic and temperature independent; taking into consideration the chemical structure with experimental data we found only one free radical structure The radical structure was simulated using the Bruker software WinEPR-Simfonia and the experimental g-value with anisotropic hyperfine coupling constants of radical were calculated as follows: g = 2.0124, aCH(4) = 26.51G, aCH(3) = 5.45G.Öğe EPR study of gamma-irradiated cholesteryl methyl carbonate(ELSEVIER SCIENCE BV, 2014) Aras, Erdal; Islek, Yasemin; Karatas, Ozgul; Abbass, Hind Kh; Birey, Mehmet; Kilic, AhmetThe electron paramagnetic resonance (EPR) of gamma-irradiated single crystals of cholesteryl methyl carbonate (C29H48O3) has been studied for different orientations of the crystals in a magnetic field. EPR spectra of cholesteryl methyl carbonate (C29H48O3 irradiated by Co-60-gamma were recorded between 125 K and 300 K for different orientations of the crystal in the magnetic field. The spectra were found to be temperature independent. In C29H48O3 single crystal,. the radiation damage centers caused by a Co-60-gamma source were determined as CH3CH2CH radical. For CH3CH2CH radical, a value of spectroscopic splitting factor g was calculated and experimentally results were supported by simulation program (WinEPR). (C) 2014 Elsevier B.V. All rights reserved.Öğe EPR STUDY OF GAMMA-IRRADIATED METHYL-4-NITROBENZOATE SINGLE CRYSTALS(KAUNAS UNIV TECHNOLOGY PRESS, 2012) Aras, Erdal; Kilic, Ahmet; Cicek, Ekrem; Meric, Yasemin; Karatas, Ozgul; Grigonis, ASingle crystals of methyl-4-nitrobenzoate C8H7NO4 have been observed and analyzed for different orientations of the crystal in the magnetic field, after being damaged at 300K by Co-60 gamma-irradiation by using Electron Paramagnetic Resonance (EPR) technique. The EPR spectrums of crystals have been taken with X-band EPR spectrometer at 150K temperature range. In C8H7NO4 single crystal, the radiation damage centers were determined to radical. For this free radical, anisotropic hyperfine splitting constants (A) and g-factors were calculated.Öğe EPR study of gamma-irradiated N-hydroxysuccinimide(TAYLOR & FRANCIS LTD, 2008) Asik, Biray; Aras, Erdal; Birey, Mehmet; Eken, MahmutThe electron paramagnetic resonance of gamma-irradiated single crystal of N-hydroxysuccinimide has been studied for different orientations of the crystals in a magnetic field. The radicals produced by gamma-irradiation have been investigated between 150 and 300 K. The spectra were found to be temperature independent and radiation damage centers were attributed to [GRAPHICS] radicals.Öğe EPR study of gamma-irradiated tetra-N-butylammonium iodide(TAYLOR & FRANCIS LTD, 2012) Merdan, Mehmet Ali; Asik, Biray; Birey, Mehmet; Aras, ErdalThe electron paramagnetic resonance of gamma-irradiated single crystal of tetra-N-butylammonium iodide has been studied for different orientations of the crystals in a magnetic field. The radical produced by gamma irradiation has been investigated at 300 K. The spectra were found to be magnetic field dependent and radiation damage centers were attributed to the (C alpha H2C beta H2C gamma H2CH3) radical. The principal values of the hyperfine coupling tensor of the unpaired electron with these atoms and the principal values of the gtensor were determined and the hyperfine coupling constants were verified by computer simulation. The results were found to be in good agreement with the existing literature data and theoretical predictions.
