X-ray Powder Diffraction for Characterization of Raw Materials in Banknotes

Current methods for detecting counterfeit banknotes often focus on visual and chemical markers. However, the crystalline composition of the paper itself has not been fully explored for forensic use. Prior research has shown that cotton-based cellulose is a key component of genuine banknotes. That uncertainty drove the need to examine the crystalline structure of both authentic and counterfeit banknotes. No prior work had resolved how polymorphs of titanium dioxide might differ by country of origin. This gap motivated the use of X-ray powder diffraction to analyze raw materials in banknotes. The study aimed to determine if crystalline composition could serve as a forensic marker. Existing knowledge lacked detailed data on filler materials in counterfeit notes. This paper's contribution is to provide a method for identifying paper sources through crystalline analysis. The findings may help improve detection of counterfeit currency.

The study aimed to compare the crystalline composition of genuine and counterfeit banknotes using X-ray powder diffraction. The specific problem addressed is the lack of forensic markers in the raw materials of counterfeit currency. The motivation is to identify unique crystalline patterns that could trace back to paper suppliers. The researchers focused on the 20-euro denomination due to its widespread circulation. They examined cotton-based cellulose and titanium dioxide in genuine notes. They also investigated unexpected additives in counterfeit samples. The goal was to determine if crystalline indices could be used for forensic identification. The study sought to establish a nondestructive method for analyzing banknote materials.

The researchers used a single-crystal X-ray diffractometer to analyze banknote samples. They measured crystalline materials in 0.5-mm sized areas to ensure precision. The method allowed for fast and nondestructive analysis of both genuine and counterfeit notes. They compared 20-euro denomination banknotes from different countries. The analysis focused on cotton-based cellulose and titanium dioxide in genuine samples. For counterfeit notes, they examined wood-pulp cellulose and unexpected additives. They identified polymorphs of TiO₂ and compared their distribution. The method also included measuring crystalline indices and peak intensity ratios.

Genuine banknotes were found to contain cotton-based cellulose and titanium dioxide. Different polymorphs of TiO₂ were identified based on the country of origin. Counterfeit notes contained wood-pulp cellulose and significant amounts of TiO₂. An unexpected mixture of TiO₂ and calcite was found in counterfeit samples. The crystalline index varied between genuine and counterfeit notes. Peak intensity ratios between cellulose and fillers were distinct. These differences suggest that counterfeit papers are not low-cost materials. The findings indicate that crystalline composition can serve as a forensic marker.

The study shows that X-ray diffraction can distinguish between genuine and counterfeit banknotes. The crystalline composition of genuine notes includes cotton-based cellulose and TiO₂ polymorphs. Counterfeit notes contain wood-pulp cellulose and unexpected additives like calcite. The presence of TiO₂ and calcite in counterfeit samples suggests a deliberate effort to mimic genuine materials. The crystalline index and peak ratios provide forensic value for identifying paper sources. These findings may help trace back suppliers of counterfeit materials. The method is nondestructive and suitable for forensic analysis. The results support the use of X-ray diffraction in banknote security research.