The photochemistry of evacuated potassium iodide solutions at 2537 Å. 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 at 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 + ion concentration. It is shown that this is in agreement with a mechanism based on the theory of diffusion controlled scavenging. 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 involution was investigated, and evidence for a pH dependent oxidation mechanism of I- by H atoms is presented, which may involve the H2+aq ion as the actual oxidizing agent.
|Number of pages||7|
|Journal||Journal of Physical Chemistry|
|State||Published - 1961|