Photosynthesis
During the photolytic phase of oxygenic photosynthesis, photons from light are captured for the photosystems, the energy of the light is then used to excite its electrons and fire them against the water molecule to break it.
In this first step the water molecule is oxidized by the removal of two electrons, releasing two protons and one oxygen atom
The electrons obtained in these reactions are then transferred to plastocyanin which transfer the electrons to ferredoxin, this enzyme is the last electrons acceptor and with its oxidation reduce the enzyme NADP reductase, which is in charge of use these electrons to reduce NADP to NADPH.
This process is repeated uncountable times, which gives as a result, an accumulation of protons inside of the Lumen. This difference between the concentration of protons inside and outside of the lumen will be used as an energetic source for the ATP synthase to convert ADP to ATP in presence of phosphorus.
Finally in a second process, the energy stored in the NADPH and ATP will be used to form carbohydrates, consuming carbon dioxide in the process.