Photobleaching

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Photobleaching

Absorbtion of light by a fluorophore elevates electrons from the ground state to an excited singlet state. Fluorescence arises from the emission of a photon during relaxation to the ground state.
The exact mechanism of photobleaching is not known, but it is assumed to be linked to a transition from the excited singlet state to the excited triplet state. The excited triplet state is relatively long-lived and is chemically more reactive.

Each fluorophore has different photobleaching-characteristics. For FRAP experiments it is important to choose a dye which bleaches minimally at low illumination power (to prevent photobleaching during image acquisition) but bleaches fast and irreversibly at high illumination power.

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contact: Stefan Terjung           last update: 02/06/04