Jablonski diagram

The states are arranged vertically by energy and grouped horizontally by spin multiplicity.

[2] The diagram is named after the Polish physicist Aleksander Jabłoński who first proposed it in 1933.

Likewise, when an excited molecule releases energy, it can do so in the form of a photon.

The changes between these levels are called "transitions" and are plotted on the Jablonski diagram.

[4] A third type is intersystem crossing (ISC); this is a transition to a state with a different spin multiplicity.

A Jablonski diagram showing the excitation of molecule A to its singlet excited state ( 1 A*) followed by intersystem crossing to the triplet state ( 3 A) that relaxes to the ground state by phosphorescence. It was used to describe absorption and emission of light by fluorescence.
Jablonski diagram including vibrational levels for absorbance, non-radiative decay, and fluorescence .
A Jablonski diagram representing Förster resonance energy transfer (FRET)