Definitions for "Photobleaching"
Light induced change in a chromophore, resulting in the loss of its absorption of light of a particular wavelength. A problem in fluorescence microscopy where prolonged illumination leads to progressive fading of the emitted light because less of the exciting wavelength is being absorbed.
The irreversible destruction of a fluorophore that is under illumination.
Photobleaching is the destruction of a photochemical fluor by high-intensity light. In microscopy, photobleaching may complicate the observation of fluorescent molecules, since they will eventually be destroyed by the light exposure necessary to stimulate them into fluorescing. This is especially problematic in time-lapse microscopy.