Abstract: In this paper, the values of g factor, ΔHpp, line shape and spin concentration of 2,4-di-(α-imino acetic acid ethyl) bcuteroporphyrin Ⅸ and 2,4-di-(α-mcrcaptoethyl) deutcroporphyrin Ⅸ on X-band were determined. The relationships of the ESR line intensity to saturation effect of microwave power, as well as the temperature were also determined. It is postulated that the ESR spectra registcd under the UV-irradiation at various temperatures were originated from single delocalized electron of porphyrin ring and oxygen dependent radical; the dependence of ESR line intensity on the saturation effect of microwave power is related to isoelectric point (pH value), but the effect of temperature is more complicated. The photochemical reaction is of zero order with respect to oxygen dependent radical and is controlled by the diffusion of the triplet oxygen to the around site of cxcited state of porphyrin.

Key words: Porphyrin(P), Photochemical reaction, Electron spin resonance spectrometry, Kinetics