Latent fingerprint deposition and effectiveness of detection are strongly affected by the surface on which prints are deposited. Material properties, surface roughness, morphology, chemistry and hydrophobicity can affect the usefulness or efficacy of forensic print development techniques. Established protocols outline appropriate techniques and sequences of processes for broad categories of operational surfaces. This work uses atomic force microscopy and scanning electron microscopy to investigate a series of surfaces classified as smooth, non-porous plastic. Latent prints developed with iron oxide powder suspension are analysed on a range of scales from macro to nano to help elucidate the interaction mechanisms between the latent fingerprint, development agent and underlying surface. Differences between surfaces have a strong effect, even within this single category. We show that both average roughness and topographical feature shape, characterized by skew, kurtosis and lay, are important factors to consider for the processing of latent fingerprints.

Early stage oxidation of a dilute‐depleted uranium‐molybdenum alloy was analysed in situ under ultra‐high vacuum conditions by AES and XPS. At the equivalent of less than 300 ns at 1‐atm O2, U‐5Mo oxidizes to form stoichiometric UO2. No molybdenum oxidation is observed. After an oxygen dose of approximately 39 L, the oxide layer approached a limiting thickness of approximately 2.4 nm. The oxidation kinetics followed a logarithmic rate law, with the best fit to the experimental data for the oxide thickness, d, being given by d = 1.26 log(0.12t + 0.56). Changes in oxygen KLL and 1s peak positions associated with transformation from chemisorbed oxygen to metal oxide were observed at similar oxygen doses of 2.3 and 2.6 L O2 by AES and XPS, respectively, which opens up the possibility of using well‐characterized XPS chemical information to inform Auger peak shifts.

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