Which pigment captures the energy for photosynthesis

Photosynthetic antenna complexes:

Solar energy is converted into chemical energy through photosynthesis by plants, algae and phototropic bacteria. Photosynthesis thus forms the basis of all life processes. The light energy is absorbed by a network of pigment-protein antenna complexes and transferred very efficiently to the photochemical reaction center. Charge separation takes place there, which supplies the free energy for further chemical reactions. The reaction begins with the absorption of a photon and ends in a stable, "charge-separated" state. This process takes place in less than 100ps (= picoseconds) with a quantum yield of more than 90%.

Chlorophylls are associated with the light-harvesting complex and specific proteins. The light-absorbing pigments are grouped into units, the photosystems. All pigments can absorb light, but only some are connected to the reaction center.
This reaction center converts the absorbed light energy into chemical energy. The other pigments are the antenna complexes, which forward the excitation energy towards the reaction center like in a funnel.

Transmission of the resonance energy in the LHC:
Top view of a reaction center with a light trap


This process is called "resonance energy transfer" in English. There is a donor and an acceptor. If both have the same excitation energy level or if it is lower at the acceptor, an energy transfer takes place. The energy level of the reaction center is lower than that of the antenna complexes and so the reaction center acts like a trap for the light energy. The animation below is intended to make the transmission of the resonance energy (vibration energy) clearer.