ESR and XPS analysis of schima superba powder after γ-rays irradiation

Electron spin resonance (ESR) and X-rays photoelectron spectroscopy (XPS) techniques were used to study the variation of the free radical, the chemical structure and components of the schima superba powder irradiated by ⁶⁰Co γ-rays. The results show that the intensity of free radicals increases with the absorbed doses according to the exponential law of I= 1 - e^-b_iD when the spectral splitting factor of the free radicals (g) is 2.0033. The O/C atomic ratio in the schima superba powder surface increases slightly after 200 kGy dose irradiation. At the same time, the contents of the C-C, C-H and C-O increase, and the C=O content decreases. The content of the -O-C=O increases to 2.5 times of the original. These phenomena may indicate that some oxygen-containing functional groups occurred on the schima superba surface and the structure of organic carbon has been changed. (authors)