Abstract: Non-green anti-Stokes luminescent material, comprising the elements Ln, erbium (Er) and ytterbium (Yb), Ln representing at least one element which is selected from the group consisting of yttrium (Y), gadolinium (Gd), scandium (Sc) and lanthanum (La), a process for its production and its use.

Abstract: Security articles comprising elements such as filaments, fibers, including hollow fibers, and threads and thin transverse sections and chopped versions thereof, wherein such elements are dispersed within the articles. Particle scattering and luminescent technology is employed based on scattering, electronic, magnetic and/or light properties to provide compound physical coloration responsive to various portions of the electromagnetic spectrum, including ultraviolet, ambient and infrared. The coloration effects can be highly stable or dependent on specific switching effects linked to, e.g., thermal exposure or actinic radiation. The security articles result in advanced levels of security to avoid counterfeiting of objects including banknote and currency paper, stock and bond certificates, identification, credit, debit and ATM cards, drivers' licenses and bar codes.