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Fluorescence
All fluorescent colorants absorb UV-light at a wavelength less than 380nm and emitt some of it at a longer wavelength. Because of that additional light energy, the fluorescence peak can reach 140% or more at the wavelength of emission.
The fluorescence depends on the UV-emission of the light source, the reason why it isn’t possible to measure these colors without a UV-calibrated light source! The fluorescence stops immediately after switching of the UV-light source. The converting of the wavelength causes stress to the molecules of the fluorescent colorant and breaks it after some time.
Fluorescent colorants show only poor light stability! Fluorescent colorants include fluorescent whitening agents (optical brightness) and the chromatic fluorescent dyes and pigments.
Phosphorescence
It’s the emission of light without changing the temperature. Electrons accumulate light energie from UV-light and emitt this energy at a different wavelength over a longer time period.
These colors are used for security signs and often for toys.
