Fluorescence is the name given to light emitted by a substance when it is illuminated (excited) by light at a shorter wavelength. The incident light causes an electron transition to a higher energy band in the molecules. The electron then spontaneously returns to its original energy state emitting a photon. The intensity of the emitted light is proportional to the concentration of the substance. Fluorescence is one form of Luminescence, especially Photoluminescence.
MitoPedia methods: Fluorometry