Pulse radiolysis of aqueous thiocyanate solution.

The pulse radiolysis of N(2)O saturated aqueous solutions of KSCN was studied under neutral pH conditions. The observed optical absorption spectrum of the SCN(*) radical in solution is more complex than previously reported, but it is in good agreement with that measured in the gas phase. Kinetic traces at 330 and 472 nm corresponding to SCN(*) and (SCN)(2)(*-), respectively, were fit using a Monte Carlo simulation kinetic model. The rate coefficient for the oxidation of SCN(-) ions by OH radicals, an important reaction used in competition kinetics measurements, was found to be (1.4 +/- 0.1) x 10(10) M(-1) s(-1), about 30% higher than the normally accepted value. A detailed discussion of the reaction mechanism is presented.