Yields of radiation products in sodium metaphosphate glasses

Metaphosphate glasses have been irradiated and dissolved in aqueous solutions, where the trapped positive and negative species, MP⁺ and MP^-, respectively, reacted with scavengers. I^-, O₂, Fe(CN)₆^4-, Fe³⁺, and TMPD have been used to scavenge MP⁺ and MP^-. From product analysis, G(MP⁺) = G(MP^-) = 2.2 ± 0.1 was calculated. Combining this with absorbance measurements in glasses yields ∈⁵⁰⁰(MP⁺) (the extinction coefficient of MP⁺ at 500 nm) = (1.92 ± 0.17) × 10³ M^-1 cm^-1. MP^- reacts with aqueous O₂ to produce peroxy radicals (O₂^- or MPO₂^-). Whatever peroxy radicals are formed, they decay in water to produce H₂O₂. MP^- does not react with N₂O and does not produce H₂ upon reaction with alcohols in acid solutions. It is concluded that MP^- does not form e_aq^- or H upon its interaction with water. Pulse radiolysis experiments show that aqueous solutions of metaphosphate are relatively inert toward e_aq^- and OH. k(e_aq^- + MP) < 1 × 10⁶ and k(OH + MP) < 5 × 10⁶ M^-1 sec^-1.