The Photochemistry of the Iodide Iok Ik Aqueous Solution

The photochemistrv of evacuated potassium iodide solutions a t 2537 b. was investigated. The dependence of the initia quantum yields on pH, iodide ion concentration and light intensity was investigated. The nature of the residual pH independent yield a t pH >3 is discussed. The pH dependence of the initial quantum yields could be represented by a linear dependence on the square root of H T ion concentration. It is shown that this is in agreement with a mechanism based on the theory of diffusion controlled scavmging. The H + ion acts as an electron scavenger for a species (electrons or H atoms) formed in the photochemical cage and yield H atoms in the bulk of the solution. The reactivity of H atoms photochemically produced in solution was investigated, and evidence for a pH dependent oxidation mechanism of Iby H atoms is presented, which may involve the Hz+aq ion as the actual oxidizing agent.