Förster theory

Förster theory, or Förster resonance energy transfer (FRET), describes how energy can transfer non-radiatively from one molecule (the donor) to another (the acceptor) through dipole-dipole interactions. This process depends on their distance (typically1-10 nanometers), spectral overlap, and relative orientation. When the donor is excited by light, it can transfer energy efficiently to the acceptor if conditions are right, leading to the acceptor emitting light or other effects. FRET is widely used in science to study molecular interactions and distances at the nanoscale, acting as a molecular ruler.