Anti-Stokes luminescent substances and use thereof in security documents

摘要

In anti-Stokes luminophors (I) for use in security documents, includes ions (absorber) for absorption of electromagnetic radiation and ions (emitter) for emission of electromagnetic radiation (anti-Stokes luminescence), so the emitted radiation has a shorter wavelength than the absorber radiation. The concentration of absorber and/or emitter is adjusted so the intensification and/or decay time of the anti-Stokes luminescence is suitable for automatic detection of (I).