Electron‐Hole Pairs in the Mechanism of the Radiation Chemistry of Non‐Polar and Polar Liquid Systems

Abstract

AbstractIt has been shown previously that after absorption of radiation leading to ionisation, in general, the electrons are at first captured in an expanded orbit around the positive ions. In media of low dielectric constants, the resulting charge‐transfer excitons are relatively long lived and they can react themselves with suitable electron or hole scavengers. If one takes into account that such electron‐hole pairs diffuse in the medium after their creation one can derive the experimentally observed dependence of the yield on the square root of the scavenger concentration. In polar media e.g. water, such electron‐hole pairs are very short lived and tend to dissociate into electrons and holes in times of the order of picoseconds. The experiments of Hunt et al. have been discussed and it has been shown that the observed dependence of the initial yields of the solvated electrons on scavenger concentration can be accounted for if one takes into account also that in the presence of scavengers, the formation of esolv− is only possible if, statistically speaking, a scavenger molecule is not sufficiently close to a radiation produced electron‐hole pair to enable it to react with it.