ABSTRACT

The interaction of light with the condensed phase results in various physical and chemical phenomena. These are rather different and are the subjects of broad research fields in physics and chemistry. The physical mechanism of the elementary act of light absorption by solutes in the visible and adjacent regions involving electron excitation consists of an electron transition from one energy level to another. A great variety of mechanisms of elementary photochemical reactions are encountered. Various types of chemical processes may be induced by light including the transfer of electrons, protons, atoms, and atom groups. The photoelectrochemical transfer of an electron from an ion in solution to an electrode is close in its physical mechanism to photoelectron emission. The total transition probability for photoelectrochemical electron transfer, as well as for photoemission, is determined by the sum of the transitions to various energy levels in the electrode.