A photodecomposition reaction is a kind of decomposition reaction wherein the reactant is broken down by absorbing energy from photons into its constituents. The decomposition into dioxygen and an oxygen radical, as illustrated by the chemical equation given below, is an example of a photo decomposition reaction.
O3+ hν → O2+ O.O3+ hν → O2+ O.
Excitation energy hops from light-capturing pigment molecules to reaction centre molecules step-by-step along the molecular energy ladder, according to the traditional, semi-classical model of photosynthetic energy transfer.
The absorption spectra of the photosynthetic pigments in the organism determine the efficiency of photons of various wavelengths. Chlorophylls absorb light in the violet-blue and red spectrums, whereas accessory pigments absorb light in other wavelengths. Red algae can photosynthesize in deep seas because their phycobilins absorb blue-green light, which penetrates further into water than red light. In the pigment molecule, each absorbed photon triggers the creation of an exciton (an electron stimulated to a higher energy state).
