Estimated Distributions of Electronic Redox Levels in aq/eaq−, Haq+/Haq and Some Other Systems

Abstract

AbstractA crude estimate of the distributions of occupied and unoccupied electronic levels of the redox systems aq/eaq− (aq: water traps) and Haq−/Haq is made using known optical and thermodynamic data of the species involved. The distribution of unoccupied levels in Haq−/Haq is thought to be rather narrow, while that of the occupied levels is wide. Under these circumstances, the hydrated electron may be expected to react with Haq− via tunneling with a nearly diffusion controlled rate. The reaction of the mobile electron with Haq− is expected to be rather slow because of the low density of unoccupied states of the system Haq−/Haq at the energy level of emobile−. Similar considerations were applied to the redox systems Haq/Haq− and OHaq/OHaq−. In both cases, the distribution of unoccupied levels is very broad. The polarograms of H and OH which have recently been measured in the 10−5 s range may be understood in terms of these estimated distribution functions. Ions of high negative redox potentials such as Mgaq2+ are expected to be more reactive towards mobile than towards hydrated electrons.