Psychology & Forensic Science, School of Applied Sciences, Abertay University, Dundee DD1 1HG, UK; School of Applied Sciences, University of Huddersfield, HD1 3DH, UK; School of Materials, University of Manchester, M13 9PL, UK.
School of Applied Sciences, University of Huddersfield, HD1 3DH, UK.
Sci Justice. 2022 Sep;62(5):644-656. doi: 10.1016/j.scijus.2022.08.007. Epub 2022 Sep 3.
The surface structure of mint (as-issued) and handled polymer five pounds sterling banknotes was studied by atomic force microscopy and laser scanning confocal microscopy. A total of 1856 fingermarks on mint and handled banknotes from four different issuing banks (Bank of England, Bank of Scotland, Royal Bank of Scotland and Clydesdale Bank) were visualised with Vacuum Metal Deposition (VMD), Cyanoacrylate Fuming (CAF) and, on Clydesdale Bank notes, magnetic fluorescent powder. VMD was significantly more effective in developing fingermarks on handled banknotes, across all the banks studied, although effectiveness varied with issuing bank. For example, on handled Bank of England notes 45% of marks showed ridge detail with VMD development and 28% with CAF; for Bank of Scotland handled notes success rates were 17% with VMD and 1% with CAF. Microscopy of degraded banknotes showed the loss of intaglio printing and the formation of a cracked surface structure in the handled notes. These features can lead to the trapping of powder, or contaminants, increasing quantity of development agent in fingermark background between the ridges, decreasing contrast and decreasing performance of powder-based fingermark development techniques. These same features can restrict the migration of components of the fingermark, preventing fingermarks degrading through spread of material and thus reducing potential formation of empty prints, so that VMD development is not adversely affected.
通过原子力显微镜和激光共聚焦扫描显微镜研究了薄荷（原样）和处理后的聚合物五英镑纸币的表面结构。总共在来自四个不同发行银行（英格兰银行、苏格兰银行、苏格兰皇家银行和克莱兹代尔银行）的薄荷和处理后的纸币上可视化了 1856 个指纹，使用真空金属沉积（VMD）、氰基丙烯酸酯熏显（CAF）和在克莱兹代尔银行钞票上使用磁性荧光粉。VMD 在开发处理后的钞票上的指纹方面明显更有效，尽管在所有研究的银行中效果因发行银行而异。例如，在处理后的英格兰银行钞票上，45%的标记显示出 VMD 开发的脊纹细节，28%的标记显示出 CAF 开发的脊纹细节；对于苏格兰银行处理后的钞票，VMD 的成功率为 17%，CAF 的成功率为 1%。对退化的钞票进行显微镜检查显示，凹版印刷丢失，处理后的钞票表面结构出现裂纹。这些特征可能导致粉末或污染物的捕获，增加脊纹之间指纹背景中的显影剂数量，降低对比度，并降低基于粉末的指纹显影技术的性能。这些相同的特征可以限制指纹成分的迁移，防止指纹因物质扩散而退化，从而减少空印的形成潜力，因此 VMD 开发不会受到不利影响。
