How do flavonoids absorb UV radiation?
So how exactly are these flavonoids shielding UV radiation?


Due to the structure of the flavonoids, there are many transitions to absorb the UV radiation. Also, there are many transitions to release the energy. Most of the time, it is released in 2 steps (2 photons) which equal the energy of the photon that exited the molecule.

Fluorescence emits a photon that is close to the same energy as the first photon. For quercetin, the excitation is at 440 nm and the emission is at 540 nm.