Browsing by All Authors "Erben, M. Talat"
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Item Determination of thallium by activation analysis based on the reaction 203T1 (n, 2n) 202T1(T. A. E. C., Çekmece Nuclear Research Center, 1966-09) Erben, M. Talat; Okar, Sevim; TAEK-ÇNAEMThermal neutron activation of thallium leads to 3.9-year 204T1 and 4.3-min. 206T1 isotopes which are not gamma emitters. However, a method of analysis based on the reaction 203T1(n, γ) 204T1 has been developed by Delbecq et al., and used to detect thallium amounts with a sensistivity of 0.1 µg. In spite of this high sensitivity, this method has the disadvantage of measuring the beta activity and therefore is not very specific. In the present note an activation analysis based on the reaction 203T1(n,2n) 202T1 is discussed. The product isotope 202T1 has a convenient half-life of 12 days and is a gamma emitter, thereby makes the determination specific. On the other hand, owing to the rather high threshold (8-9 MeV) for this reaction the sensitivity is only about 20 µg of thallium for samples irradiated for 30 hours in the close-vicinity of the reactor fuel in a total flux of 10(13) n/cm2/sec.Item Inversion of the cyanide group into iso-cyanide under gamma irradiation(T.A.E.C., Çekmece Nuclear Research Center, 1965-10) Erben, M. Talat; Ünseren, Envare; Seber, Nurten; TAEK-ÇNAEMInfrared spectrophotometric evidence indicates that gamma irradiation of the nitriles causes partial inversion of the cyanide group into iso-cyanide according to the following mechanism: In the gamma flux, some of the cyanide groups are detached from the nitrile as cyan free radicals and, owing to their resonance-hybrid structure, .C=N - <-> - C=N., two distinct recombination processes take place leading partly to the usual cyanide and partly to the iso-cyanide, respectively. From a comparison of the optical densities at the characteristic frequency of the iso-cyanide absorption band in irradiated methacrylonitrile and ethyl iso-cyanide it is concluded that at least 20% of the cyanide groups were transformed into iso-cyanide in a specific sample of methacrylonitrile irradiated to a total dose of 0.1 megarads.Item Isotopic and isotonic yields in nuclear fission(T.A.E.C. Çekmece Nuclear Research Center, 1962) Erben, M. Talat; Güven, Binay; TAEK-ÇNAEMThe curves for isotopic and isotonic fission yields are calculated and shown to be the Weierstrass transforms of the isoboaric yield curve. The Well-known mass asymmetry of the fission is associated with asymmetry in charge and in neutron contents. There are "forbidden" zones at 44 Z 48 and at 64 N 78, where formation probabilities are extremely low. The distribution of the number of neutrons of the fission fragments is much narrower than what would be expected on the basis of the variation ranges for Z and N. The ambiguity existing about whether the fragments of a pair are meant to complement before or after prompt neutron boil-off is removed, and Glendenin's treatment is confirmed. There are indications, which are in full agreement with the properties of Wahl's empirical Z(p) function, that the proton closed shell contribution (if any) to the fine structure observed in the isobaric yield curve may be larger than the contribution of the neutron closed shell. The isotopic yields of the known nuclides are significantly smaller than the yields defined by the full theoretical curves for Z = 38, 39, 40, 41, 52, and 57, indicating that new isotopes of Sr, Y, Zr, Nb, Te, and La are still to be identified as primary fission products from the thermal neutron fission of U(235).Item Kinetics of the reaction of Tetrachloro-p-Benzoquinone with TRI-n-Dodecyl amine(T.A.E.C. Çekmece Nuclear Research Center, 1965-10) Erben, M. Talat; Dinçler, Güngör; TAEK-ÇNAEMThe kinetics of the reaction of chloranil with tri-n-dodecyl amine have been investigated in the temperature range 100-115.5°C and in the concentration range 0.036-0.0697 M. The kinetics follow a simple second-order mechanism. The energy of activation is 19.7 Kcal./mole. The reaction product is a quaternary amnonium salt, (trichloro-p-benzoquinonyl)-tri-n-dodecyl ammonium chloride. The rate constant is given by: k = 5.74 x 10(10) exp(-9950/T) (minute)(-1) (mole)(-1)Item Part I. Thermodynamic functions as particular cases of a single generating function : part II. cyclic properties of thermodynamic functions(T. A. E. C., Çekmece Nuclear Research Center, 1969-05) Erben, M. Talat; TAEK-ÇNAEMBölüm I de, bütün termodinamik potansiyelleri , yani iç enerji E yi, Helmholtz serbest enerjisi F yi, Gibbs serbest enerjisi G yi ve entalpi H yi özel hal olarak veren genel bir jeneratris fonksiyon tarif edilmektedir. Bölüm II de, termodinamik değişkenler ( S, P, T, V ) ile termodinamik fonksiyonlar ( E, F, G, H ) sirküler bir diagram şeklinde dizilmekte ve bu diagram sayesinde pek çok termodinamik bağıntıların biribirinden sirküler permütasyon yoluyla çıkartıla- bildikleri gösterilmektedir.Item The complex chemistry of uranylnitrate - P - aminobenzoic acid system(T.A.E.C., Çekmece Nuclear Research And Training Center, 1973) Bal, Y.; Erben, M. Talat; TAEK-ÇNAEMUranil iyonu ve p-aminobenzoik asit arasındaki kompleks oluşumu % 50 alkol-su ortamında spektrofotometrik olarak incelenmiştir. Neticeler, çok yüksek ligand konsantrasyonlarında bile bütün ligantın bağlandığını göstermektedir. Böylece, bir uranil iyonu ile kompleks yapan ligand moleküllerinin ortalama sayısı koordinasyon sayısını pek çok aşarak 170 ve daha da yüksek değerlere erişmektedir.