THE FORMATION OF HYDRATED ELECTRONS FROM THE EXCITED STATE OF INDOLE DERIVATIVES

Abstract— –Hydrogen atoms can be observed in u.v. irradiated aqueous solutions of indole derivatives. These H' atoms are produced in a reaction between H⁺ and solvated electrons which are formed in the excited state of indole. Protons are also known to be good quenching agents for the fluorescence of indole. However the pH dependence and effect of oxygen on the yield of hydrogen atoms indicates clearly that although both fluorescence and electron ejection originate in the excited singlet state the fluorescence quenching by protons is not caused by a transfer of electronic charge from the excited ring to H⁺. The temperature dependencies of both fluorescence and electron ejection yield an abnormally large "activation energy". It is proposed that this temperature dependence is to a large extent determined by a process characteristic of water as a solvent.