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Öğe Analysis of Polycrystal Acrylamide by Electron Spin Resonance and Thermo-Analytical Methods(WILEY-BLACKWELL, 2011) Usta, Ayhan; Filiz, Ali; Birey, Mehmet; Ozmen, AyhanElectron spin resonance (ESR), thermogravimetry analysis (TGA), and differential thermal analysis (DTA) were performed on acrylamide (C(3)H(5)NO) polycrystal samples. The samples were irradiated at 298 K for 24, 48, 72, and 96 h using (60)Co - gamma source. ESR measurements were carried out between 120 and 450 K. The ESR signals were recorded from the samples exposed to (60)Co - gamma rays for 72 and 96 h. Between 120 and 450 K the spectra changed in a manner roughly. It was detected by means of e.s.r. spectra that unpaired electron took place due to scission of pi bond in the carbon-carbon double bonds in the substance. The produced radiation damage center on the sample was attributed to center dot CH(2)-CH-R Additionally, thermal behavior of the acrylamide samples were investigated by using TGA and DTA methods. It was observed that both irradiated and not irradiated samples decomposed at three steps. (C) 2011 Wiley Periodicals, Inc. Concepts Magn Reson Part A 38A: 102-106, 2011.Öğe CW-EPR Study of 2,2,4,4-Tetramethyl-3-Pentanone Oxime Single Crystals(PERGAMON-ELSEVIER SCIENCE LTD, 2010) Sayın, Ülkü; Yüksel, Hüseyin; Özmen, Ayhan; Birey, MehmetThe electron paramagnetic resonance (EPR) spectra of gamma irradiated single crystals of 2,2,4,4-tetramethyl-3-pentanone oxime (TPO) have been examined between temperatures of 125 and 450 K. The spectra were found to be both dependent on temperature and orientation of single crystals with magnetic field. We attributed radiation damage centers to iminoxy radicals (RC = (N) over dotO). There are two similar group of splitting in the spectra because of conformational isomers (R1, R2) of iminoxy radicals produced by gamma irradiation of TPO. Determined g-factor and hyperfine coupling constants for RI and R2 conformers were found anisotropic with the average values (g(iso))(R1) = 2.01057, (g(iso))(R2)=2.009337. [(a(N))(iso)](R1)=28.09 G, [(a(N))(iso)](R2)=36.34 G, [(a(H))(iso)](R2)=9.15 G, respectively.Öğe Effect of irradiation on ethyl 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate: an ESR study(WILEY-BLACKWELL, 2012) Usta, Ayhan; Birey, Mehmet; Sari, Nursen; Altundas, Aliye; Nartop, DilekEthyl 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate [C11H15NO2S] was synthesized by the Gewald method. Its single crystals were grown from an alcohol/ethyl acetate solution at 15 degrees C and characterized using IR and 1H-NMR. These single crystals were irradiated for 72h at 298K by a 60Co gamma source with a dose speed of 0.864kGy/h. After irradiation, electron spin resonance (ESR) measurements were carried out to study radiation-induced radicals in the temperature range from 120 to 450K. Additionally, for the single crystal, ESR angular dependencies were measured in the xy, xz and yz planes of the substance. This irradiated single crystal was analyzed based on the ESR spectra. Analysis of the spectra revealed that the radical was formed by a CH bond fission at the carbon end of the substance. It was also observed that the color of the sample changed after irradiation. The hyperfine and g parameters were determined from the experimental spectra. It was inferred from these results that the hyperfine parameters and g value exhibited anisotropic behavior. The average values of these parameters were calculated as follows: g=2.0088, AH1=H2=20.70G, AH3=H4=10.80G, AHa=4.59G, AHb=3.24G and, AN=6.10G. Copyright (c) 2011 John Wiley & Sons, Ltd.Öğe EPR of Gamma Irradiated Single Crystals of Amphi-Chloroglyoxime(Taylor & Francis Ltd, 2006) Sayın, Ülkü; Yüksel, Hüseyin; Yıldırım, Bilge; Birey, Mehmety-irradiated single crystals of amphi-chloroglyoxime were investigated by the electron paramagnetic resonance (EPR) between 123 and 400 K temperature. Paramagnetic species produced in the crystals were attributed to the R-HCCNOH radical and relevant spectra were found to be temperature inde- pendent. The g-factor and hyperfine coupling constants of the R-HCCNOH radical were found to be almost isotropic with the average values g 2.0009, ac 31.89 G, ??? = 23.83 G. ??? = 9.49G and the spin densities PEN = %50, PHCC = 250.Öğe An EPR study on irradiated 4-(1,3,5-triazin-2-yloxy)cyclohexanecarbaldehyde single crystal(ELSEVIER SCIENCE BV, 2011) Usta, Ayhan; Ozmen, Ayhan; Birey, MehmetThe single crystals of 4-(1,3,5-triazin-2-yloxy)cyclohexanecarbaldehyde [C(10)H(13)N(3)O(2)] were produced by slow evaporation of a concentrated ethyl acetate solutions. These single crystals were exposed to (60)Co gamma rays with dose speed of 0.980 kGy/h at the room temperature for 48 and 72 h. The free radical of the sample was observed using EPR-X band spectrometer.The EPR spectra were recorded between 120 and 450 K. The sample irradiated for 72 h was rotated in steps of 10 degrees and analysed for different orientations of the crystal in the magnetic field. The hyperfine constants of the sample were found to be anisotropic. The average values of these constants were calculated as following: g = 1.9979, a(H1) = 10.75 G, a(H2) = 2.28 G, and a(N) = 3.83 (C) 2010 Elsevier B.V. All rights reserved.Öğe Gamma-ışınlarına maruz bırakılan 4-metilbenzilamin glioksim tek kristalinin EPR ve simülasyon tekniği ile incelenmesi(2005) Akpınar, Ülkü; Yüksel, Hüseyin; Yıldırım, Bilge; Birey, Mehmet\gamma — ışınlarına maruz bırakılan 4-Metil Benzilamin Glioksim (4-MBG) tek kristallerinin elektron paramanyetik rezonansı, manyetik alanda kristalin farklı yönelimleri için gözlenmiş ve analiz edilmiştir. 4-MBG tek kristalleri 100 K ve 400 K arasındaki sıcaklıklarda incelenmiştir, g-faktörünün ortalama değeri ve aşırı ince yapı yarılmasının değerleri sırası ile g 1,999, a_N 14G, a_{H(NH)} 13,5G ve a_{CH_2} 7,5G olarak bulunmuştur. Çiftlenmemiş elektronun P_{N(NH)} 05 ve P_{H(NH)} 0,5 ile sırasıyla azot ve hidrojen üzerinde lokalize olduğunu ölçümler göstermiştir. Çiftlenmemiş elektron ile protonlar ve azotun g değeri ve aşırı ince yapı etkileşme sabitleri EPR ve simülasyon tekniği ile belirlenmiştir.Öğe IDENTIFICATION OF RADICAL STRUCTURE IN 2,4-DINITROCHLOROBENZENE SINGLE CRYSTAL BY EPR(EDITURA ACAD ROMANE, 2011) Usta, Ayhan; Zengin, Mehmet; Birey, MehmetThe single crystals of the 2,4 dinitrochlorobenzen were grown by slow evaporation of concentrated ethanol solution. Some of these single crystals exposed to Co-60-gamma rays with dose rate of 0.880 kGy/h at room temperature for 48 and 72 h. The EPR spectra were recorded as a function of temperature and orientations of the single crystal in the magnetic field. The single crystal irradiated for 72 h was rotated in steps of 100 in three mutually perpendicular planes in the magnetic field. The ESR temperature measurements were performed between 120 K and 440 K. The spectra recorded were found to be dependent on the temperature and the orientations of the crystal. It was also detected that only a radical structure and color centers were occurred after irradiation. The average values of g and hyperfine coupling constants were calculated as follow: a(Na=Nb)=13.70 G, a(H1=H2)=8.95 G, a(H3)=7.06 G, g=2.0039.Öğe Magnetic properties of gamma irradiated single crystals of cholesteryl chloride: An EPR study(PERGAMON-ELSEVIER SCIENCE LTD, 2011) Sayin, Ulku; Yuksel, Huseyin; Birey, MehmetThe cholesteryl chloride compound has been irradiated with Co-60-gamma ray at room temperature. The radical produced by gamma irradiation has been investigated in the range of temperatures 123-450 K for different orientations of the crystal in a magnetic field by electron paramagnetic resonance (EPR). Radiation damage center was attributed to radical CH alpha CH2 beta CH2 gamma. The g factor and hyperfine coupling constants have slight dependency on temperature and evident dependency on the orientation of the magnetic field. Determined g factor and hyperfine coupling constants for the radical CH alpha CH2 beta CH2 gamma, were found to be anisotropic with the average values g(av) = 2.003222,(a(CH alpha))(av) = 16.82G and (a(CH2 beta))(av) = 23.94G measured in all axes and (a(CH2 gamma))(av) = 8G, which was measured only in one axis. (C) 2011 Elsevier Ltd. All rights reserved.Öğe X-band EPR study on benzo[c]cinnoline single crystals(TAYLOR & FRANCIS LTD, 2007) Usta, Ayhan; Zengin, Mehmet; Olmez, Oznur; Birey, MehmetThe benzo[c]cinnoline compound has been crystallized in ethanol solution. These crystals have been irradiated with Co-60 gamma-rays at room temperature. The crystals have been investigated by an X-band electron spin resonance (ESR) spectrometer two days after irradiation. Very strong ESR peaks have been observed at the temperatures between 130 and 430 K. However, a line broadening has been observed at 130K. Also analyses found that EPR specra are temperature-dependent and show anisotropic behaviour.
