PRINTING INK, ITS USE FOR THE AUTHENTICATION OF ARTICLES, ARTICLES OBTAINED THEREBY AND AUTHENTICATION METHODS

摘要

A printing ink having a first fluorescent dye acting as donor and a second fluorescent dye acting as acceptor. The first fluorescent dye, upon excitation by electromagnetic radiation falling within an excitation wavelength range λ1a of the first fluorescent dye, is capable of emitting electromagnetic radiation in at least one first emission wavelength range λ1e, said first emission wavelength range λ1e of the first fluorescent dye overlapping with at least one excitation wavelength range λ2a of the second fluorescent dye, to thereby excite the second fluorescent dye to emit electromagnetic radiation in a second emission wavelength range λ2e.