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In chemistry, many reactions depend on the absorption of photons to provide the energy needed to overcome the activation energy barrier and hence can be labelled light-dependent. Such reactions range from the silver halide reactions used in photographic film to the creation and destruction of ozone in the upper atmosphere .
The theory of solar cells explains the process by which light energy in photons is converted into electric current when the photons strike a suitable semiconductor device. The theoretical studies are of practical use because they predict the fundamental limits of a solar cell , and give guidance on the phenomena that contribute to losses and ...
Photosynthesis occurs in two stages. In the first stage, light-dependent reactions or light reactions capture the energy of light and use it to make the hydrogen carrier NADPH and the energy-storage molecule ATP. During the second stage, the light-independent reactions use these products to capture and reduce carbon dioxide.
Solar chemical processes use solar energy to drive chemical reactions. These processes offset energy that would otherwise come from a fossil fuel source and can also convert solar energy into storable and transportable fuels. Solar induced chemical reactions can be divided into thermochemical or photochemical. [101]
The fact that a reaction is thermodynamically possible does not mean that it will actually occur. A mixture of hydrogen gas and oxygen gas does not spontaneously ignite. It is necessary either to supply an activation energy or to lower the intrinsic activation energy of the system, in order to make most biochemical reactions proceed at a useful ...
The antenna complex is where light is captured, while the reaction center is where this light energy is transformed into chemical energy. At the reaction center, there are many polypeptides that are surrounded by pigment proteins. At the center of the reaction center is a special pair of chlorophyll molecules. Each PSII has about 8 LHCII.
The photosynthetic efficiency (i.e. oxygenic photosynthesis efficiency) is the fraction of light energy converted into chemical energy during photosynthesis in green plants and algae. Photosynthesis can be described by the simplified chemical reaction 6 H 2 O + 6 CO 2 + energy → C 6 H 12 O 6 + 6 O 2
Photosynthesis is a process where light is absorbed or harvested by pigment protein complexes which are able to turn sunlight into energy. [3] Absorption of a photon by a molecule takes place when pigment protein complexes harvest sunlight leading to electronic excitation delivered to the reaction centre where the process of charge separation can take place.