Bond John W
Northamptonshire Police, Force HQ, Wootton Hall, Northampton, NN4 OJQ, UK.
J Forensic Sci. 2011 Sep;56(5):1285-8. doi: 10.1111/j.1556-4029.2011.01834.x. Epub 2011 Jul 21.
The reflection of visible light from α-phase brass subject to surface oxidation in air at elevated temperatures is investigated. X-ray photoelectron and auger electron spectroscopy confirm that covered areas of brass (not exposed to air) display dezincification but an absence of significant surface oxidation, confirming a differential oxidation mechanism. Visualization of differential oxidation is shown to be enhanced by selective digital mapping of colors reflected from the surface of the brass using Adobe(®) Photoshop(®). Enhancement is optimal when the brass is heated to ∼ 250°C with areas of oxidation having a mirror-like appearance. The use of this enhancement method to produce a faithful image of fingerprint ridge characteristics is demonstrated on brass shell casings where fingerprints were deposited prefiring.
研究了在高温空气中进行表面氧化的α相黄铜对可见光的反射。X射线光电子能谱和俄歇电子能谱证实，黄铜的覆盖区域（未暴露于空气中）显示出脱锌现象，但没有明显的表面氧化，这证实了一种差异氧化机制。通过使用Adobe(®) Photoshop(®)对黄铜表面反射的颜色进行选择性数字映射，显示出差异氧化的可视化得到了增强。当黄铜加热到约250°C时，氧化区域具有镜面外观，增强效果最佳。在预发射时已沉积指纹的黄铜弹壳上，展示了使用这种增强方法来生成指纹脊特征的真实图像。
