The mechanism of O 3P atom formation in γ-ray irradiated and UV photolyzed aqueous solutions

Abstract

O 3P atoms form by excitation processes in the radiolysis and photolysis of the oxyhalate ions, BrO - 3 and ClO - 4. However, the mechanism for O 3P formation by the radiolysis of dilute alkaline solutions involves non-excitation processes. Evidence for this conclusion is provided by a comparison of “direct effect” calculations on these systems. They demonstrate that the relative yield of O 3P from OH - is 15-fold greater than that of BrO - 3 thus indicating a more effective mechanism for O 3P formation in alkaline solutions. The expected increase in G(H 2) from the postulated excitation decay reaction: (OH -) *=O 3P+H - followed by H -+H 2O=H 2+OH - could not be confirmed. Neither water nor OH - produce O 3P when irradiated at 184.9 nm. However relatively high yields of O 3P form in alkaline H 2O 2 solutions photolyzed at 253.7 nm. A possible reaction is: O -+OH=O 3P+OH -. The participation of sub-excitation electrons in aqueous radiolytic excitation phenomena is further explored in the radiolysis of formate solutions.