November 12, 2012
Croatian scientists have discovered that counterfeit banknotes can be easily identified by testing for yellow toner by the Raman spectrum.
Spectroscopy Now has reported on the recent findings of Croatian scientists that links counterfeit banknotes with yellow toner, and potentially leading to a forensic spectral library of yellow toners in a bid to crack down on counterfeit banknotes.
Analysing 44 commercial cyan, magenta and yellow toners using 36 printers from 10 manufacturers, the tests were conducted using micro-Raman spectroscopy and an excitation wavelength of 514.5 nm.
The results revealed that, when subtracting the spectrum of the paper, the spectra of cyan toners were identical and magenta toners showed slight differences. However yellow toner often resulted in substantial differences, even in toners from the same manufacturer, between different cartridges and those intended to work in different printer models.
To determine whether the test would produce results on paper currency, two counterfeit Croatian banknotes that were suspected of originating from the same source were tested, and the Reman spectra of the magenta and yellow colours were stated as identical, pointing to a common origin. The results were backed up by conventional counterfeit protection code patterns.
The researchers state that this disparity between results allows tests to be conducted to determine the origins of suspected counterfeit toners, and only the yellow toners need to be examined. The study still requires further validation across a wider selection of toners, but researchers speculate that this could lead to a forensic spectral library of yellow toners.
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