Time-Dependent Radiolytic Yield of OH• Radical Studied by Picosecond Pulse Radiolysis

Abstract

Picosecond pulse radiolysis measurements using a pulse-probe method are performed to measure directly the time-dependent radiolytic yield of the OH^• radical in pure water. The time-dependent absorbance of OH^• radical at 263 nm is deduced from the observed signal by subtracting the contribution of the hydrated electron and that of the irradiated empty fused silica cell which presents also a transient absoption. The time-dependent radiolytic yield of OH^• is obtained by assuming the yield of the hydrated electron at 20 ps equal to 4.2 × 10^–7 mol J^–1 and by assuming the values of the extinction coefficients of e_aq^– and OH^• at 782 nm (ε_λ=782 nm = 17025 M^–1 cm^–1) and at 263 nm (ε_λ=263 nm = 460 M^–1 cm^–1), respectively. The value of the yield of OH^• radical at 10 ps is found to be (4.80 ± 0.12) × 10^–7 mol J^–1.