| abstract |
Security papers with luminescing authenticity features worked into them or printed on them. The authenticity features used consist of a luminophore and one or more absorbing materials by which the emission and/or the excitation spectrum of the luminophore is changed in detectable fashion. The dyestuff can be present as an admixture to the luminophore, as a coating of a luminophore layer or as a coating on luminophore powder grains. For checking the authenticity of documents the emission spectrum of the luminophore is not used but the change generated by the technology used in the emission or excitation spectra. |