O(3P) Atom Formation in γ- and 184.9-nm-Irradiated Aqueous Perchlorate Solutions

Article abstract of DOI:10.1021/j100455a005

O(³P) atom formation was studied in γ-irradiated and 184.9-nm-photolyzed aqueous perchlorate solutions by measuring the ethylene resulting from the O(³P) reaction with cyclopentene (CP).The linearity of G(O(³P)) with perchlorate concentration in the range 0.1-4 M gives evidence of a "direct-action effect", and its relative independence of CP concentration shows that O(³P) is quite unreactive with the perchlorate ion.The rate-constant ratio, k(O(³P) + ClO4(1-))/k(O(³P) + CP), was studied by competition expenriments carried out by photolysis of ClO(1-) at 366 nm; it is < 5.4 x 1E-5.Quantum yield measurements, carried out on 1.0 and 2 M solutions, reveal that the photolysis produces O(³P) with a quantum yield of unity. Φ(O2) = 0.53.The γ-ray-induced formation of O(³P) is attributed to direct excitation of ClO4(1-) by energy-rich secondary electrons, e_s(1-), in competition with energy-loss processes in water and sodium ions.Excitations of perchlorate ion to a state forming O(³P) atoms proceeds with a direct-effect yield, G_de(O(³P)), of 0.28, only a small fraction of G_de(-ClO4(1-)), which is 5.1.Some experiments with added Na2SO4 are also reported.