Jablonski diagram

The Jabłoński diagram or Jabłoński term scheme (proposed in 1931 by Aleksander Jabłoński ) illustrates the possible transitions of valence electrons in the various excited states upon exposure to light and back. It provides a graphic representation of the phenomena of fluorescence and phosphorescence, and therefore it plays a major role in the UV / VIS spectroscopy.

When radiation of electromagnetic waves electrons are excited by absorption of the energy of the incident photon, from its ground state to higher-energy states (so-called orbitals ). The relaxation to the ground state can be accomplished in various ways, which are exemplified by Jablonski diagram:

• In most cases by radiationless deactivation, where the absorbed energy is used for the excitation of degrees of freedom of translation, rotation and vibration (internal conversion ).

• Radiative deactivation from the emission of light, which is referred to as luminescence: If the electron is in an excited triplet state and thus to return to the ground state a spin reversal needed ( intersystem crossing ), it is called phosphorescence
• When spinerlaubtem transition from a singlet state is called fluorescence.