Thermal features of radiation induced radical of gamma irradiated gallic acid

Abstract

In the present work, temperature effects of gamma irradiated anhydrous and monohydrate gallic acid components were investigated using Electron Paramagnetic Resonance (EPR) spectroscopy.  While unirradiated samples presented no EPR signal, irradiated samples were observed to exhibit an EPR spectrum consisting of an intense resonance line at the middle and weak lines on both sides.  Thermal features of the radicals responsible of experimental EPR spectrum were explored trough the variations of the peak-to-peak amplitude and spectrum area under the EPR spectra.  Also the high temperature annealing stability of the radicals was investigated.  It is calculated that the activation energies of the main two radicals that contributed to the experimental spectra of GA-a and GA-m compounds was 64.68 kJ/mol and 88.11 kJ/mol, and 35.88 kJ / mol and 127.64 kJ/mol, respectively.

Keywords

• Electron Paramagnetic Resonance (EPR),gallic acid,irradiation,thermal features

Gama radyasyonu ile ışınlanan gallik asitte oluşan radikallerin termal özellikleri

Abstract

Bu çalışmada sıcaklığın, gama radyasyonu sonucunda gallik asit anhydrous (GA-a) ve gallik asit monohydrate (GA-m) bileşenlerine olan etkisi Elektron Paramanyetik Rezonans (EPR) spektroskopisi kullanılarak incelenmiştir.  Işınlanmamış örneklerde herhangi bir EPR sinyali gözlenmezken, ışınlanmış örnekler merkezde ve her iki tarafında yer alan bir EPR spektrumu verdiği gözlenmiştir.  Deneysel EPR spektrumuna kaynaklık eden radikallerin termal özellikleri tepeden-tepeye sinyal şiddeti ve spektrum altında kalan alan dikkate alınarak araştırılmıştır.  Ayrıca radikallerin yüksek sıcaklıkta tavlama sonucunda radikallerin kararlılığı araştırılmıştır.  GA-a ve GA-m örneklerinin deneysel spektrumlarına katkı getiren iki ana radikalin aktivasyon enerjileri sırasıyla 64.68 kJ/mol ve 88.11 kJ/mol, ve 35.88 kJ/mol ve 127.64 kJ/mol olduğu hesaplanmıştır.

Keywords

• Elektron Paramanyetik Rezonans (EPR),gallik asit,ışınlama,termal özellikler

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