SURFACE-REACTIONS WITH HOT-ELECTRONS AND HOT HOLES IN METALS

Electrochemical reactions (oxidation or reduction) start when the elec tronic levels of the redoxsystem within the electrolyte cross the Ferm i level E(F) of the electrode - from below to above E(F) in the case o f the oxidation and from above to below in the case of reduction. This energetic shift of the redox level is effected by changing the electr ochemical potential of the electrode. Hot electrons above E(F) or hot holes below E(F) incident at the metal-electrolyte interface from the metal side may induce reduction and oxidation, respectively, at electr ochemical potentials where no reactions occur with the electrode in it s electronic ground state. This is related to surface photochemistry, believed to be induced by intermediate hot electrons. In the present w ork hot electrons and hot holes are injected into a thin silver film e lectrode by tunnelling within a metal-insulator-silver contact. The re sults presented here confirm the new unusual reactions, provided there is either atomic scale roughness or a suitable redox level at the sil ver-electrolyte interface.