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

Excitation of liquid methanol with low-intensity light of variable wavelength and electron scavenging by NO3- strongly suggest that, in the threshold energy region, excess electrons are produced by a proton-transfer reaction from an electronically excited neutral MeOH molecule. The 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 feasible. Mass spectrometry observations also support the view that such proton phototransfer and the classical photoionization process may coexist above the photoconductivity threshold of the associated liquids.