Light behaves both as a wave and a particle. A pigment is any substance that absorbs light. The colour of the pigment comes from the wavelengths of light reflected. Chlorophyll is a complex molecule. If a pigment absorbs light energy, one of three things will occur.
Energy is dissipated as heat.
The energy may be emitted immediately as a longer wavelength, a phenomenon known as fluorescence. Energy may trigger a chemical reaction, as in photosynthesis. Different pigments absorb different wavelengths to maximise the efficiency or absorption. OHP CC pigments Absorption spectrum. The light is absorbed by magnesium and electrons are forced to a higher energy level.