Patent ID: 7767315

Claim:
A method of authenticating or identifying an article that has been marked with or incorporates a fluorescent complex that, when exposed to ultra-violet light, produces a main emission peak at a main emission frequency of the complex and a set of side peaks at frequencies different from the main emission frequency of the complex, said complex being selected from the group consisting of: A. type (i) materials having the general chemical formula ( L α) n >M←Lp where: M is an element selected from the group consisting of lanthanide series elements and actinide series elements, n is the valence state of the element M, Lα is an organic complex which consists of a single ligand or multiple ligands which may be the same or different, and Lp is an organic complex which consists of a single ligand or multiple ligands which may be the same or different; and, B. type (ii) materials having the general chemical formula (Lα) n M 1 M 2 where: M 1 is an element selected from the group consisting of rare earth elements, transition elements, lanthanide series elements and actinide series elements, M 2 is a non rare earth metal, Lα is an organic complex which consists of a single ligand or multiple ligands which may be the same or different, and n is the combined valence state of M 1 and M 2 , said method comprising the steps of: (a) calculating a first series of numbers corresponding to the ratios of the sizes of the side peaks for the fluorescent complex relative to the size of the main emission peak for the fluorescent complex; (b) shining ultra-violet light onto the article and thereby producing a combination of a main emission peak for the article at a main emission frequency and a set of smaller side peaks for the article at frequencies different from the main frequency; (c) determining the size of the main emission peak for the article at the main emission frequency of the fluorescent complex, and also determining the sizes of the side peaks for the article at least one or more frequencies different from the main emission frequency; (d) calculating a second series of numbers corresponding to the ratios of the sizes of the side peaks for the article relative to the size of the main emission peak for the article, said numbers being unique to a the fluorescent complex; and, (e) authenticating or identifying the article by comparing the similarity of the ratios in the second series of numbers obtained for the article with the corresponding ratios in the first series of numbers.