| A novel encoding system, compositions for use therein and methods for
determining the source, location and/or identity of a particular item or
component of interest is provided. In particular, the present invention utilizes
a collection of one or more sizes of populations of semiconductor nanocrystals
having characteristic spectral emissions, to "track" the source or location of
an item of interest or to identify a particular item of interest. The
semiconductor nanocrystals used in the inventive compositions can be selected to
emit a desired wavelength to produce a characteristic spectral emission in
narrow spectral widths, and with a symmetric, nearly Gaussian line shape, by
changing the composition and size of the semiconductor nanocrystal.
Additionally, the intensity of the emission at a particular characteristic
wavelength can also be varied, thus enabling the use of binary or higher order
encoding schemes. |
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