Ion-forming processes on 248 nm laser excitation of benzophenone in aqueous solution: a time-resolved absorption and conductivity study

Abstract

The laser flash photolysis (excitation at 248 nm) of benzophenone in aqueous solution was investigated using absorption and conductivity measurements. In addition to intersystem crossing to the ground state, benzophenone triplets undergo triplet—triplet (T—T) annihilation partly by an electron transfer reaction leading to cation and anion radicals. A second ion-forming process is two-photon photoionization which leads to radical cations and hydrated electrons. Secondary reactions, involving the protolytic equilibrium between ketyl radicals and anion radicals, are observed and discussed.