Förster Resonance Energy Transfer

Förster Resonance Energy Transfer (FRET) is a process where energy is transferred non-radiatively from one molecule (the donor) to another (the acceptor) through close proximity, typically within 1-10 nanometers. When the donor molecule is excited by light, it can pass its energy directly to the acceptor molecule if the acceptor's absorption spectrum overlaps with the donor's emission, causing the acceptor to become excited. This phenomenon is useful in studying molecular interactions and distances at a very small scale, such as in biological systems, because changes in energy transfer efficiency indicate how close or interacting two molecules are.