Fluorescence and Counterfieting

Fluorescence is an emission of electromagnetic radiation. Certain organic dyes are fluorescent, when hit within a certain wavelength range they emit light at a greater wavelength. The wavelength and intensity of this light depends on the physical and chemical properties of the materials to which the dye was applied.

To make a product counterfeit-proof, multiple dyes can be added to the material in very minute quantities, such as just a few parts per billion, to create a marker. At such low concentrations, the marker is virtually impossible to decode, and the counterfeit protection cannot be removed since it permeates the whole material. Fluorescent dye markers produce precise characteristics so it is easy to recognize if the material is original or if it is a copy.

Reference:
Fraunhofer-Gesellschaft (2010, June 15). Brilliant counterfeit protection. ScienceDaily. Retrieved June 18, 2010, from http://www.sciencedaily.com­ /releases/2010/06/100614093627.htm

Study Questions

1. What is meant by the term electromagnetic radiation?
2. Fluorescein is an example of a fluorescent dye that has been used as a marker for airplanes downed at sea. Find the structural formula for fluorescein.
3. Some fluorescent compounds are used as fabric whiteners in washing powders and are referred to as optical bleaches. Find an example of an optical bleach and describe how it works.
   
4. A number of naturally occurring minerals are fluorescent. Can you list examples of these?
5. Phosphorescence is similar to fluorescence. What is the difference between phosphorescence and fluorescence?
6. If an aqueous solution of fluorescein has a concentration of 175ppb, what is its equivalent concentration in,

• ppm
• parts per hundred
• g/mL
• μg/mL
• mol/L