PHOTOEMISSION FROM METALS AND THE SLOWING OF LOW-ENERGY ELECTRONS IN WATER

A characteristic cut-off length L of the image potential, at which the '5/2 photoemission law' becomes valid, was found within the framework of the threshold theory of photoelectron emission. It is shown that t he transition from the Fowler law to the 5/2 law takes place at L less -than-or-equal-to 5 angstrom, so subsequent slowing of the emitted ele ctron proceeds similarly to that in bulk water under pulse radiolysis. Adopting a model of random motion of 'dry' electrons in water, as det ermined by large cross-sections of elastic scattering, we considered t he slowing of electrons associated with inelastic scattering. The ther malization lengths of electrons with initial energies ranging from 0.5 to 3.5 eV, as found from experimental values of these cross-sections, agree satisfactorily with the results of photoemission measurements w ithout any additional assumptions.