Fluorescence, photochemical fading

As an example of the potential usefulness of such fractions, we also report their use as a probe of the physical basis of the photochemical fading of acridine orange bound to heparin. Fluorescence fading under continuous irradiation is a second-order photochemical reaction of adjacently-bound acridine orange ions in which photooxidation leads to irreversible loss of fluorescence, with the role of heparin being catalytic... 

Photobleaching (fading) Photochemical reaction of fluorophore, light and oxygen that causes the intensity of the fluorescence emission to decrease with time. 

Figure 3. Postcolor number of filter papers saturated to a level of 3% add-on with arabinogalactan. Key (thermal discoloration) , 50% rh and 90 °C , 0% rh and 90 °C and (photochemical discoloration) , daylight fluorescent lamps A, BLB fluorescent lamps V, Fade-ometer.

J. M. Menter, R. E. Hurst, and S. S. West, Photochemistry of Heparin-Acridine Orange Complexes in Solution Photochemical Changes Occurring in the Dye and Polymer on Fluorescence Fading, Photochem. Photobiol 29, 473-478 (1979). 

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