Bond John W
Scientific Support Unit, Northamptonshire Police, Wootton Hall, Northampton, UK.
J Forensic Sci. 2009 Sep;54(5):1034-41. doi: 10.1111/j.1556-4029.2009.01108.x. Epub 2009 Jul 22.
Visualization of latent fingerprint deposits on metals by enhancing the fingerprint-induced corrosion is now an established technique. However, the corrosion mechanism itself is less well understood. Here, we describe the apparatus constructed to measure the spatial variation (DeltaV) in applied potential (V) over the surface of brass disks corroded by latent fingerprint deposits. Measurement of DeltaV for potential of 1400 V has enabled visualization of fingerprint ridges and characteristics in terms of this potential difference with DeltaV typically of a few volts. This visualization is consistent with the formation of a Schottky barrier at the brass-corrosion product junction. Measurement of the work function of the corroded brass of up to 4.87 +/- 0.03 eV supports previous results that suggested that the corrosion product is composed of p-type copper oxides. A model for the galvanic corrosion of brass by ionic salts present in fingerprint deposits is proposed that is consistent with these experimental results.
通过增强指纹引发的腐蚀来可视化金属上的潜在指纹沉积物，现在已是一项成熟的技术。然而，腐蚀机制本身却不太为人所理解。在此，我们描述了一种构建的仪器，用于测量因潜在指纹沉积物而被腐蚀的黄铜盘表面上施加电势（V）的空间变化（ΔV）。对1400 V电势下的ΔV进行测量，已能够根据通常为几伏的这种电势差来可视化指纹纹路和特征。这种可视化与在黄铜 - 腐蚀产物交界处形成肖特基势垒相一致。对腐蚀后的黄铜功函数高达4.87±0.03 eV的测量支持了先前的结果，即表明腐蚀产物由p型氧化铜组成。提出了一个由指纹沉积物中存在的离子盐对黄铜进行电偶腐蚀的模型，该模型与这些实验结果一致。
