The pulse radiolysis of aqueous solutions of simple RCN compounds

Fast kinetic spectrophotometry was used to study the absorption spectra of short-living intermediates produced by reactions of RCN molecules with H, e_aq⁻ and OH. The spectra were obtained on the microsecond time scale after an electron pulse from a Febetron 707 accelerator in aqueous solutions of the following compounds: hydrocyanic acid, acetonitrile, propionitrile, malononitrile and succinonitrile. It has been found that all intermediates absorb in the U.V. range (λ⩽300 nm) and disappear by fast bimolecular processes with decay rate constants of about 10⁹dm³mol⁻¹s⁻¹. In the presence of an efficient scavenger for hydroxyl radicals, the same transient spectra were registered in acid and neutral solutions suggesting that the protonations of e_aq⁻ adducts of these RCN molecules were complete within a submicrosecond time interval.