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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 fluorescents.
Intersystem crossing (ISC) is an isoenergetic radiationless process involving a transition between the two electronic states with different spin multiplicity. [ 1 ] Excited electrons can undergo intersystem crossing to a degenerate state with a different spin multiplicity.
Jablonski diagram indicating intersystem crossing (left) and internal conversion (right). Internal conversion is a transition from a higher to a lower electronic state in a molecule or atom. [1] It is sometimes called "radiationless de-excitation", because no photons are emitted.
A Jablonski diagram describing the sensitization process in triplet-triplet annihilation upconversion. The sensitizer first absorbs light and reaches its first singlet excited state (S 1). The sensitizer S 1 state undergoes intersystem crossing (ISC) to the triplet excited state (T 1).
Triplet states typically have longer lifetimes than excited singlets. The prolonged lifetime increases the probability of interacting with other molecules nearby. Photosensitizers experience varying levels of efficiency for intersystem crossing at different wavelengths of light based on the internal electronic structure of the molecule. [2] [7]
The re-emitted photon in this case is said to be red shifted, referring to the reduced energy it carries following this loss (as the Jablonski diagram shows). For phosphorescence, electrons which absorbed photons, undergo intersystem crossing where they enter into a state with altered spin multiplicity (see term symbol), usually a triplet state ...
Fluorescence is illustrated schematically with the classical Jablonski diagram, first proposed by Jabłoński in 1933 [2] to describe absorption and emission of light. In 1946, he settled in Toruń where he was appointed Head of the Faculty of Physics at the Nicolaus Copernicus University .
English: Jablonski diagram of absorbance, non-radiative decay, and fluorescence. Electronic transitions are about 1 eV. Vibrational transitions are about 0.1 eV. Rotational transitions (not shown) are about 0.001 eV. Absorption is about 1 femtosecond, relaxation takes about 1 picosecond, fluorescence takes about 1 nanosecond.