Ayhan Usta

An EPR study on single crystals of dimethyl-1,3-cyclohexanedione by γ-rays

Single crystals of dimethyl-1,3-cyclohexanedione (C8H12O2) were produced by slow evaporation of the concentrated ethyl acetate solutions. These single crystals were exposed to 60Co γ -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 γ -rays was rotated in steps of 10° 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.

Identification of radical structures on 1‐pentamethylbenzyl‐3‐ethylimidazoliumsilver(I)bromide and 1,3‐bis(pentamethylbenzyl)‐4,5‐dimethylbenzimidazoliumsilver(I)bromide exposed to gamma rays: an EPR study

1‐Pentamethylbenzyl‐3‐ethylimidazoliumsilver(I)bromide and 1,3‐bis(pentamethylbenzyl)‐4,5dimethylbenzimidazoliumsilver(I)bromide and their Ag+ complexes were synthesized and their polycrystal forms were produced by recrystallization in dichloromethane/Et2O solvent system. Structural determinations were carried out by 1H NMR and 13C NMR with a Varian 400 NMR system using tetramethylsilane as internal standard and CDCl3 as solvent. The disappearance of acidic N‐heterocyclic carbene proton showed the formation of Ag(I) complexes. Also, elemental analyses were carried out. Electron paramagnetic resonance (EPR) measurements were performed to determine the formed radical structure on the samples irradiated at the room temperature for 72 h by using 60Co‐source with dose rate of 0.680 kGy. The EPR measurements were carried out in the temperature range of 200 K–450 K. Identical radicals were determined on the irradiated compounds. It was observed that the shapes of the spectra of the samples were independent of the temperature but, the resonance line intensities changed linearly with the temperature. Also, it was detected that the free radical on the 1‐pentamethylbenzyl‐3‐ethylimidazoliumsilver(I)bromide is not stable compared to that on the 1,3‐bis(pentamethylbenzyl)‐4,5dimethylbenzimidazoliumsilver(I)bromide. Copyright

Investigation of irradiated 1H-Benzo[b]pyrrole by ESR, thermal methods and learning algorithm

ABSTRACT 1H-Benzo[b]pyrrole samples were irradiated in the air with gamma source at 0.969 kGy per hour at room temperature for 24, 48 and 72 h. After irradiation, electron spin resonance, thermogravimetry analysis (TGA) and differential thermal analysis (DTA) measurements were immediately carried out on the irradiated and unirradiated samples. The ESR measurements were performed between 320 and 400 K. ESR spectra were recorded from the samples irradiated for 48 and 72 h. The obtained spectra were observed to be dependent on temperature. Two radical-type centres were detected on the sample. Detected radiation-induced radicals were attributed to R-+•NH and R=•CC2H2. The g-values and hyperfine constants were calculated by means of the experimental spectra. It was also determined from TGA spectrum that both the unirradiated and irradiated samples were decomposed at one step with the rising temperature. Moreover, a theoretical study was presented. Success of the machine learning methods was tested. It was found that bagging techniques, which are widely used in the machine learning literature, could optimise prediction accuracy noticeably.

An EPR Study on Radiation-Induced 2-(piperidin-1-ylmethyl)phenol Single Crystal

An EPR Study on Radiation-Induced 2-(piperidin-1-ylmethyl)phenol Single Crystal K. Usta, Y. Ceylanb,∗, A. Usta, N. Ceylan and E. Aras Alanya Alaaddin Keykubat University, Department of Metallurgical and Materials Engineering, Antalya, Turkey Selcuk University, Department of Physics, Konya, Turkey Alanya Alaaddin Keykubat University, Department of Mechanical Engineering, Antalya, Turkey Giresun University, Department of Chemistry, Giresun, Turkey Gazi University, Department of Physics, Ankara, Turkey

X-band EPR study on benzo[c]cinnoline single crystals

The benzo[c]cinnoline compound has been crystallized in ethanol solution. These crystals have been irradiated with 60Coγ-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 130 K. Also analyses found that EPR specra are temperature-dependent and show anisotropic behaviour.