Guide alphabétique, de la thermodynamique, amplification de chaleur, transfert de masse, et dynamique des fluides
Français English Русский 中文 Português Español Deutsch À propos Comité de rédaction Contactez-nous Accès Begell House
View in A-Z Index

In general phosphorescence is the long-lived emission of light which persists for longer than about one hundred nanoseconds after excitation. Shorter lived emission is termed fluorescence. The term is derived from the latin phosphorus-light bringing.

In molecular photochemistry, phosphorescence is defined as the emission of light associated with a transition between states of different spin multiplicity and usually arises from the transition from the first excited triplet to the ground state singlet. As discussed by Turro (1991) such transitions are "forbidden" and hence occur relatively slowly. Because of the long life of the triplet state the excited-state energy can be efficiently "quenched" in fluid solution, it is usual to work at 77 K in rigid organic glasses to observe phosphorescence. However in some cases, where molecules contain atoms other than those from the first row of the periodic table (e.g., halogenated polyaromatics and complexes of second or third row transition elements), room temperature phosphorescence can be detected. Oxygen is an efficient quencher of phosphorescence in fluid solution. Phosphorescence emission lies at lower energy than fluorescence. (See Photoluminescence for further details.)

The term phosphorescence is often used in solid state photophysics to indicate a temperature dependent emission process involving recombination of trapped electrons and holes (see also Thermoluminescence).

REFERENCES

Turro, N. J. (1991) Modern Molecular Photochemistry, University Science Books, California.

References

  1. Turro, N. J. (1991) Modern Molecular Photochemistry, University Science Books, California.
Nombre de vues : 17906 Article ajouté : 2 February 2011 Dernière modification de l'article : 4 February 2011 © Copyright 2010-2021 Retour en haut de page
Index A-Z Auteur / Rédacteurs Carte sémantique Galerie visuelle Contribuez Guest