ON THE SO-CALLED IONIZATION-POTENTIAL OF WATER AND ASSOCIATED LIQUIDS

Excitation of liquid methanol with low-intensity light of variable wav elength and electron scavenging by NO3- strongly suggest that, in the threshold energy region, excess electrons are produced by a proton-tra nsfer reaction from an electronically excited neutral MeOH molecule. T he observed threshold is located at about 4.7 eV. Literature data for liquid water photoionization and the presently proposed energy balance indicate that such a proton-transfer reaction can kinetically compete with the H2O homolytic dissociation and that it is energetically feas ible. Mass spectrometry observations also support the view that such p roton phototransfer and the classical photoionization process may coex ist above the photoconductivity threshold of the associated liquids.