Flow Cytometry

A fluorescent compound has the property of absorbing light energy at a range of specific wavelengths. This absorption of light causes electron to rise from the ground state to a higher energy level (excited state). The excited electron quickly decays to its ground state while releasing the excess energy in the form of photon of light. This transition of energy is called fluorescence. https://www.creative-bioarray.com/support/fluorochromes-in-flow-cytometry.htm