S’ State Mechanism consists of a series of 5 states called as S0, S1, S2, S3 and S4. Each state acquires a positive charge by a photon (hv) and after the S4 state, it acquires 4 positive charges, four electrons and the evolution of oxygen. Two molecules of water go back to the S0. At the end of photolysis 4H+, 4e– and O2 are evolved from water.
