Departamento de Física, Universidade Estadual de Londrina, Londrina, PR 86057-970, Brazil.
Departamento de Física, Universidade Estadual de Londrina, Londrina, PR 86057-970, Brazil.
Forensic Sci Int. 2019 Sep;302:109872. doi: 10.1016/j.forsciint.2019.06.030. Epub 2019 Jul 4.
As technology advances, counterfeiters improve their techniques reproducing banknotes with more accuracy. Spectroscopic techniques may be applied for characterization of these forgeries. The aim of this study was to develop a methodology for banknotes characterization employing portable X-ray fluorescence (pXRF) and portable Raman spectroscopy (RS) equipment for measurements in genuine and counterfeit Real (Brazilian currency) banknotes. Quantification of the metals in the ink and paper was carried out with pXRF data, using a sensitivity curve. pXRF spectral analysis was effective to discriminate between genuine and counterfeit bills. Moreover, the quantification of the metals enriched the analysis, since it was possible to compare elements concentration that are commonly found in genuine and counterfeit banknotes. The use of partial least square discriminant analysis (PLS-DA) applied to pXRF data was efficacious to identify fake banknotes and it may be used for further investigation about the provenance of forgeries. Principal component analysis (PCA) grouped forgeries from different seizures based on similarities in the elemental composition. The spectra obtained by RS allowed identification of characteristic bands of two pigments from the inks: phthalocyanine and diarylide. For the RS data, PLS-DA and PCA successfully discriminated R$ 50 genuine and fake banknotes.
随着技术的进步，造假者提高了复制钞票的技术精度。光谱技术可用于这些伪造钞票的特征描述。本研究旨在开发一种使用便携式 X 射线荧光（pXRF）和便携式拉曼光谱（RS）设备对真实（巴西货币）钞票的真伪进行测量的钞票特征描述方法。使用灵敏度曲线对 pXRF 数据进行油墨和纸张中金属的定量分析。pXRF 光谱分析可有效区分真假钞票。此外，金属的定量分析丰富了分析，因为可以比较真假钞票中常见的元素浓度。偏最小二乘判别分析（PLS-DA）应用于 pXRF 数据可有效识别假钞，并可用于进一步调查伪造钞票的来源。主成分分析（PCA）根据元素组成的相似性将来自不同缴获物的伪造钞票进行分组。通过 RS 获得的光谱允许识别油墨中两种颜料的特征带：酞菁和二芳基。对于 RS 数据，PLS-DA 和 PCA 成功地区分了 R$50 真钞和假钞。
